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Srikrishna Sekhar authored 11d23f30ace Merge 
Merge remote-tracking branch 'origin/master' into CAS-13901

Resolved minor merge conflict in tclean.xml
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casatasks/xml/tclean.xml

Modified
19 19 ​
20 20 ​
21 21 ​
22 22 ​
23 23 ​
24 24 <param type="any" name="vis" kind="ms" mustexist="true">
25 25 <shortdescription>Name of input visibility file(s)</shortdescription>
26 26 <description>Name(s) of input visibility file(s)
27 27 default: none;
28 28 example: vis='ngc5921.ms'
29 - vis=['ngc5921a.ms','ngc5921b.ms']; multiple MSes
29 + vis=['ngc5921a.ms','ngc5921b.ms']; multiple MSs
30 30 </description>
31 31
32 32 <type mustexist="true">path</type><type mustexist="true">pathVec</type>
33 33 <value type="string"/>
34 34 </param>
35 35 ​
36 36 ​
37 37 <param type="bool" name="selectdata" visibility="hidden">
38 38 <shortdescription>Enable data selection parameters</shortdescription>
39 39 <description>Enable data selection parameters.
40 40 </description>
41 41 <value type="bool">True</value>
42 42 </param>
43 43 ​
44 44 <param type="any" name="field" subparam="true">
45 45 <shortdescription>field(s) to select</shortdescription>
46 46 <description> Select fields to image or mosaic. Use field id(s) or name(s).
47 47 ['go listobs' to obtain the list id's or names]
48 - default: ''= all fields
48 + default: ''= all fields.
49 49 If field string is a non-negative integer, it is assumed to
50 - be a field index otherwise, it is assumed to be a
51 - field name
52 - field='0~2'; field ids 0,1,2
53 - field='0,4,5~7'; field ids 0,4,5,6,7
54 - field='3C286,3C295'; field named 3C286 and 3C295
55 - field = '3,4C\*'; field id 3, all names starting with 4C
50 + be a field index, otherwise it is assumed to be a
51 + field name.
52 + field='0~2'; field ids 0,1,2.
53 + field='0,4,5~7'; field ids 0,4,5,6,7.
54 + field='3C286,3C295'; field names 3C286 and 3C295.
55 + field = '3,4C\*'; field id 3, all names starting with 4C.
56 56 For multiple MS input, a list of field strings can be used:
57 57 field = ['0~2','0~4']; field ids 0-2 for the first MS and 0-4
58 - for the second
59 - field = '0~2'; field ids 0-2 for all input MSes
58 + for the second.
59 + field = '0~2'; field ids 0-2 for all input MSs.
60 60 ​
61 61 </description>
62 62 <type>string</type><type>stringVec</type>
63 63 <value type="string"/>
64 64 </param>
65 65 ​
66 66 <param type="any" name="spw" subparam="true">
67 67 <shortdescription>spw(s)/channels to select</shortdescription>
68 -<description> Select spectral window/channels
69 - NOTE: channels de-selected here will contain all zeros if
70 - selected by the parameter mode subparameters.
71 - default: ''=all spectral windows and channels
72 - spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
73 - spw='0:5~61'; spw 0, channels 5 to 61
74 - spw='&lt;2'; spectral windows less than 2 (i.e. 0,1)
75 - spw='0,10,3:3~45'; spw 0,10 all channels, spw 3,
68 +<description> Select spectral window/channels.
69 + NOTE: channels not selected here will contain all zeros if
70 + selected by other subparameters.
71 + default: ''=all spectral windows and channels.
72 + spw='0~2,4'; spectral windows 0,1,2,4 (all channels).
73 + spw='0:5~61'; spw 0, channels 5 to 61.
74 + spw='&lt;2'; spectral windows less than 2 (i.e. 0,1).
75 + spw='0,10,3:3~45'; spw 0,10 all channels, and spw 3
76 76 channels 3 to 45.
77 77 spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
78 78 For multiple MS input, a list of spw strings can be used:
79 - spw=['0','0~3']; spw ids 0 for the first MS and 0-3 for the second
80 - spw='0~3' spw ids 0-3 for all input MS
81 - spw='3:10~20;50~60' for multiple channel ranges within spw id 3
82 - spw='3:10~20;50~60,4:0~30' for different channel ranges for spw ids 3 and 4
79 + spw=['0','0~3']; spw ids 0 for the first MS and 0-3 for the second.
80 + spw='0~3' spw ids 0-3 for all input MS.
81 + spw='3:10~20;50~60' for multiple channel ranges within spw id 3.
82 + spw='3:10~20;50~60,4:0~30' for different channel ranges for spw ids 3 and 4.
83 83 spw='0:0~10,1:20~30,2:1;2;3'; spw 0, channels 0-10,
84 - spw 1, channels 20-30, and spw 2, channels, 1,2 and 3
85 - spw='1~4;6:15~48' for channels 15 through 48 for spw ids 1,2,3,4 and 6
84 + spw 1, channels 20-30, and spw 2, channels, 1,2 and 3.
85 + spw='1~4;6:15~48' for channels 15 through 48 for spw ids 1,2,3,4 and 6.
86 86 ​
87 87 </description>
88 88 <type>string</type><type>stringVec</type>
89 89 <value type="string"/>
90 90 </param>
91 91 ​
92 92 <param type="any" name="timerange" subparam="true">
93 93 <shortdescription>Range of time to select from data</shortdescription>
94 94 <description>Range of time to select from data
95 95 ​
96 96 default: '' (all); examples,
97 97 timerange = 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss'
98 98 Note: if YYYY/MM/DD is missing date defaults to first
99 - day in data set
100 - timerange='09:14:0~09:54:0' picks 40 min on first day
99 + day in data set.
100 + timerange='09:14:0~09:54:0' picks 40 min on first day.
101 101 timerange='25:00:00~27:30:00' picks 1 hr to 3 hr
102 - 30min on NEXT day
102 + 30min on NEXT day.
103 103 timerange='09:44:00' pick data within one integration
104 - of time
105 - timerange='&gt; 10:24:00' data after this time
104 + of time.
105 + timerange='&gt; 10:24:00' data after this time.
106 106 For multiple MS input, a list of timerange strings can be
107 107 used:
108 - timerange=['09:14:0~09:54:0','&gt; 10:24:00']
108 + timerange=['09:14:0~09:54:0','&gt; 10:24:00'].
109 109 timerange='09:14:0~09:54:0''; apply the same timerange for
110 - all input MSes
110 + all input MSs.
111 111 ​
112 112 </description>
113 113 <type>string</type><type>stringVec</type>
114 114 <value type="string"/>
115 115 </param>
116 116 ​
117 117 <param type="any" name="uvrange" subparam="true">
118 118 <shortdescription>Select data within uvrange</shortdescription>
119 119 <description>Select data within uvrange (default unit is meters)
120 120 default: '' (all); example:
121 - uvrange='0~1000klambda'; uvrange from 0-1000 kilo-lambda
122 - uvrange='&gt; 4klambda';uvranges greater than 4 kilo lambda
121 + uvrange='0~1000klambda'; uvrange from 0-1000 kilo-lambda.
122 + uvrange='&gt; 4klambda';uvranges greater than 4 kilo lambda.
123 123 For multiple MS input, a list of uvrange strings can be
124 124 used:
125 - uvrange=['0~1000klambda','100~1000klamda']
125 + uvrange=['0~1000klambda','100~1000klamda'].
126 126 uvrange='0~1000klambda'; apply 0-1000 kilo-lambda for all
127 - input MSes
127 + input MSs.
128 + uvrange='0~1000'; apply 0-1000 meter for all input MSs.
128 129 </description>
129 130 <type>string</type><type>stringVec</type>
130 131 <value type="string"/>
131 132 </param>
132 133 ​
133 134 <param type="any" name="antenna" subparam="true">
134 135 <shortdescription>Select data based on antenna/baseline</shortdescription>
135 136 <description>Select data based on antenna/baseline
136 137 ​
137 138 default: '' (all)
138 139 If antenna string is a non-negative integer, it is
139 140 assumed to be an antenna index, otherwise, it is
140 141 considered an antenna name.
141 142 antenna='5\&amp;6'; baseline between antenna index 5 and
142 143 index 6.
143 144 antenna='VA05\&amp;VA06'; baseline between VLA antenna 5
144 145 and 6.
145 - antenna='5\&amp;6;7\&amp;8'; baselines 5-6 and 7-8
146 - antenna='5'; all baselines with antenna index 5
146 + antenna='5\&amp;6;7\&amp;8'; baselines 5-6 and 7-8.
147 + antenna='5'; all baselines with antenna index 5.
147 148 antenna='05'; all baselines with antenna number 05
148 - (VLA old name)
149 + (VLA old name).
149 150 antenna='5,6,9'; all baselines with antennas 5,6,9
150 - index number
151 + index number.
151 152 For multiple MS input, a list of antenna strings can be
152 153 used:
153 154 antenna=['5','5\&amp;6'];
154 - antenna='5'; antenna index 5 for all input MSes
155 - antenna='!DV14'; use all antennas except DV14
155 + antenna='5'; antenna index 5 for all input MSs.
156 + antenna='!DV14'; use all antennas except DV14.
156 157 ​
157 158 </description>
158 159 <type>string</type><type>stringVec</type>
159 160 <value type="string"/>
160 161 </param>
161 162 ​
162 163 <param type="any" name="scan" subparam="true">
163 164 <shortdescription>Scan number range</shortdescription>
164 165 <description>Scan number range
165 166 ​
166 - default: '' (all)
167 - example: scan='1~5'
167 + default: '' (all).
168 + example: scan='1~5'.
168 169 For multiple MS input, a list of scan strings can be used:
169 - scan=['0~100','10~200']
170 - scan='0~100; scan ids 0-100 for all input MSes
170 + scan=['0~100','10~200'].
171 + scan='0~100; scan ids 0-100 for all input MSs.
171 172 ​
172 173 </description>
173 174 <type>string</type><type>stringVec</type>
174 175 <value type="string"/>
175 176 </param>
176 177 ​
177 178 <param type="any" name="observation" subparam="true">
178 179 <shortdescription>Observation ID range</shortdescription>
179 180 <description>Observation ID range
180 - default: '' (all)
181 - example: observation='1~5'
181 + default: '' (all).
182 + example: observation='1~5'.
182 183 </description>
183 184 <type>string</type><type>int</type>
184 185 <value type="string"/>
185 186 </param>
186 187 ​
187 188 <param type="any" name="intent" subparam="true">
188 189 <shortdescription>Scan Intent(s)</shortdescription>
189 190 <description>Scan Intent(s)
190 191 ​
191 - default: '' (all)
192 - example: intent='TARGET_SOURCE'
193 - example: intent='TARGET_SOURCE1,TARGET_SOURCE2'
194 - example: intent='TARGET_POINTING\*'
192 + default: '' (all).
193 + example: intent='TARGET_SOURCE'.
194 + example: intent='TARGET_SOURCE1,TARGET_SOURCE2'.
195 + example: intent='TARGET_POINTING\*'.
195 196 </description>
196 197 <type>string</type><type>stringVec</type>
197 198 <value type="string"/>
198 199 </param>
199 200 ​
200 201 <param type="string" name="datacolumn">
201 202 <shortdescription>Data column to image(data,corrected)</shortdescription>
202 203 <description>Data column to image (data or observed, corrected)
203 204 default:'corrected'
204 205 ( If 'corrected' does not exist, it will use 'data' instead )
213 214 ​
214 215 ​
215 216 <param type="any" name="imagename" required="true">
216 217 <shortdescription>Pre-name of output images</shortdescription>
217 218 <description>Pre-name of output images
218 219 ​
219 220 example : imagename='try'
220 221 ​
221 222 Output images will be (a subset of) :
222 223 ​
223 - try.psf - Point spread function
224 - try.residual - Residual image
225 - try.image - Restored image
226 - try.model - Model image (contains only flux components)
227 - try.sumwt - Single pixel image containing sum-of-weights.
228 - (for natural weighting, sensitivity=1/sqrt(sumwt))
229 - try.pb - Primary beam model (values depend on the gridder used)
224 + try.psf - Point Spread Function (PSF).
225 + try.residual - Residual image.
226 + try.image - Restored image.
227 + try.model - Model image (contains only flux components).
228 + try.sumwt - Single pixel image containing sum-of-weights.
229 + (for natural weighting, sensitivity=1/sqrt(sumwt)).
230 + try.pb - Primary Beam (PB) model (values depend on the gridder used).
230 231 ​
231 232 Widefield projection algorithms (gridder=mosaic,awproject) will
232 233 compute the following images too.
233 234 try.weight - FT of gridded weights or the
234 - un-normalized sum of PB-square (for all pointings)
235 - Here, PB = sqrt(weight) normalized to a maximum of 1.0
235 + un-normalized sum of PB-square (for all pointings).
236 + Here, PB = sqrt(weight) normalized to a maximum of 1.0.
236 237 ​
237 238 For multi-term wideband imaging, all relevant images above will
238 239 have additional .tt0,.tt1, etc suffixes to indicate Taylor terms,
239 240 plus the following extra output images.
240 - try.alpha - spectral index
241 - try.alpha.error - estimate of error on spectral index
242 - try.beta - spectral curvature (if nterms \&gt; 2)
241 + try.alpha - spectral index.
242 + try.alpha.error - estimate of error on spectral index.
243 + try.beta - spectral curvature (if nterms \&gt; 2).
243 244 ​
244 245 Tip : Include a directory name in 'imagename' for all
245 246 output images to be sent there instead of the
246 - current working directory : imagename='mydir/try'
247 + current working directory : imagename='mydir/try'.
247 248 ​
248 249 Tip : Restarting an imaging run without changing 'imagename'
249 250 implies continuation from the existing model image on disk.
250 251 - If 'startmodel' was initially specified it needs to be set to &quot;&quot;
251 252 for the restart run (or tclean will exit with an error message).
252 253 - By default, the residual image and psf will be recomputed
253 254 but if no changes were made to relevant parameters between
254 255 the runs, set calcres=False, calcpsf=False to resume directly from
255 256 the minor cycle without the (unnecessary) first major cycle.
256 257 To automatically change 'imagename' with a numerical
263 264 </description>
264 265 <type>int</type><type>string</type><type>stringVec</type>
265 266 <value type="string"/>
266 267 </param>
267 268 ​
268 269 <param type="any" name="imsize">
269 270 <shortdescription>Number of pixels</shortdescription>
270 271 <description>Number of pixels
271 272 example:
272 273 ​
273 - imsize = [350,250]
274 - imsize = 500 is equivalent to [500,500]
274 + imsize = [350,250].
275 + imsize = 500 is equivalent to [500,500].
275 276
276 277 To take proper advantage of internal optimized FFT routines, the
277 278 number of pixels must be even and factorizable by 2,3,5 only.
278 279 To find the nearest optimal imsize to that desired by the user, please use the following tool method:
279 280 ​
280 281 from casatools import synthesisutils
281 282 su = synthesisutils()
282 283 su.getOptimumSize(345)
283 284 Output : 360
284 285 </description>
285 286 <type>int</type><type>intVec</type>
286 287 <value type="intVec"><value>100</value></value>
287 288 </param>
288 289 ​
289 290 <param type="any" name="cell">
290 291 <shortdescription>Cell size</shortdescription>
291 292 <description>Cell size
292 293 example: cell=['0.5arcsec,'0.5arcsec'] or
293 - cell=['1arcmin', '1arcmin']
294 - cell = '1arcsec' is equivalent to ['1arcsec','1arcsec']
294 + cell=['1arcmin', '1arcmin'].
295 + cell = '1arcsec' is equivalent to ['1arcsec','1arcsec'].
295 296 </description>
296 297 <type>int</type><type>double</type><type>intVec</type><type>doubleVec</type><type>string</type><type>stringVec</type>
297 298 <value type="stringVec">&quot;1arcsec&quot;</value>
298 299 </param>
299 300 ​
300 301 <param type="any" name="phasecenter">
301 302 <shortdescription>Phase center of the image</shortdescription>
302 303 <description>Phase center of the image (string or field id); if the phasecenter is the name known major solar system object ('MERCURY', 'VENUS', 'MARS', 'JUPITER', 'SATURN', 'URANUS', 'NEPTUNE', 'PLUTO', 'SUN', 'MOON') or is an ephemerides table then that source is tracked and the background sources get smeared. There is a special case, when phasecenter='TRACKFIELD', which will use the ephemerides or polynomial phasecenter in the FIELD table of the MS's as the source center to track.
303 304 ​
304 305 Note : If unspecified, tclean will use the phase-center from the first data field of the MS (or list of MSs) selected for imaging.
305 306 ​
306 - example: phasecenter=6
307 - phasecenter='J2000 19h30m00 -40d00m00'
308 - phasecenter='J2000 292.5deg -40.0deg'
309 - phasecenter='J2000 5.105rad -0.698rad'
310 - phasecenter='ICRS 13:05:27.2780 -049.28.04.458'
311 - phasecenter='myComet_ephem.tab'
312 - phasecenter='MOON'
313 - phasecenter='TRACKFIELD'
307 + example: phasecenter='6'.
308 + phasecenter='J2000 19h30m00 -40d00m00'.
309 + phasecenter='J2000 292.5deg -40.0deg'.
310 + phasecenter='J2000 5.105rad -0.698rad'.
311 + phasecenter='ICRS 13:05:27.2780 -049.28.04.458'.
312 + phasecenter='myComet_ephem.tab'.
313 + phasecenter='MOON'.
314 + phasecenter='TRACKFIELD'.
314 315 </description>
315 316 <type>int</type><type>string</type>
316 317 <value type="string"/>
317 318 </param>
318 319 ​
319 320 ​
320 321 <param type="string" name="stokes">
321 322 <shortdescription>Stokes Planes to make</shortdescription>
322 323 <description>Stokes Planes to make
323 324 default='I'; example: stokes='IQUV';
324 325 Options: 'I','Q','U','V','IV','QU','IQ','UV','IQUV','RR','LL','XX','YY','RRLL','XXYY','pseudoI'
325 326 ​
326 327 Note : Due to current internal code constraints, if any correlation pair
327 328 is flagged, by default, no data for that row in the MS will be used.
328 329 So, in an MS with XX,YY, if only YY is flagged, neither a
329 330 Stokes I image nor an XX image can be made from those data points.
330 331 In such a situation, please split out only the unflagged correlation into
331 - a separate MS.
332 + a separate MS, or use the option 'pseudoI'.
332 333 ​
333 334 Note : The 'pseudoI' option is a partial solution, allowing Stokes I imaging
334 335 when either of the parallel-hand correlations are unflagged.
335 336 ​
336 337 The remaining constraints shall be removed (where logical) in a future release.
337 338 ​
338 339 </description>
339 340 <value type="string">I</value>
340 341 <allowed kind="enum">
341 342 <value>I</value>
353 354 <value>YY</value>
354 355 <value>RRLL</value>
355 356 <value>XXYY</value>
356 357 <value>pseudoI</value>
357 358 </allowed>
358 359 </param>
359 360 ​
360 361 <param type="string" name="projection">
361 362 <shortdescription>Coordinate projection </shortdescription>
362 363 <description>Coordinate projection
363 - Examples : SIN, NCP
364 + Examples : SIN, NCP.
364 365 A list of supported (but untested) projections can be found here :
365 366 http://casa.nrao.edu/active/docs/doxygen/html/classcasa_1_1Projection.html#a3d5f9ec787e4eabdce57ab5edaf7c0cd
366 367 ​
367 368 ​
368 369 ​
369 370 </description>
370 371 <value type="string">SIN</value>
371 372 </param>
372 373 ​
373 374 <param type="any" name="startmodel">
374 375 <shortdescription>Name of starting model image</shortdescription>
375 376 <description>Name of starting model image
376 377 ​
377 378 The contents of the supplied starting model image will be
378 379 copied to the imagename.model before the run begins.
379 380 ​
380 - example : startmodel = 'singledish.im'
381 + example : startmodel = 'singledish.im'.
381 382 ​
382 383 For deconvolver='mtmfs', one image per Taylor term must be provided.
383 - example : startmodel = ['try.model.tt0', 'try.model.tt1']
384 + example : startmodel = ['try.model.tt0', 'try.model.tt1'].
384 385 startmodel = ['try.model.tt0'] will use a starting model only
385 386 for the zeroth order term.
386 387 startmodel = ['','try.model.tt1'] will use a starting model only
387 388 for the first order term.
388 389 ​
389 390 This starting model can be of a different image shape and size from
390 391 what is currently being imaged. If so, an image regrid is first triggered
391 392 to resample the input image onto the target coordinate system.
392 393 ​
393 - A common usage is to set this parameter equal to a single dish image
394 + A common usage is to set this parameter equal to a single dish image.
394 395 ​
395 396 Negative components in the model image will be included as is.
396 397 ​
397 - [ Note : If an error occurs during image resampling/regridding,
398 + Note : If an error occurs during image resampling/regridding,
398 399 please try using task imregrid to resample the starting model
399 400 image onto a CASA image with the target shape and
400 - coordinate system before supplying it via startmodel ]
401 + coordinate system before supplying it via startmodel.
401 402 ​
402 403 </description>
403 404 <value type="string"/>
404 405 </param>
405 406 ​
406 407 ​
407 408 ​
408 409 ​
409 410 ​
410 411 ​
411 412 ​
412 413 <param type="string" name="specmode" required="true">
413 414 <shortdescription>Spectral definition mode (mfs,cube,cubedata, cubesource,mvc)</shortdescription>
414 415 <description>Spectral definition mode (mfs,cube,cubedata, cubesource, mvc)
415 416 ​
416 417 specmode='mfs' : Continuum imaging with only one output image channel.
417 418 (mode='cont' can also be used here)
418 419 ​
419 - specmode='cube' : Spectral line imaging with one or more channels
420 + specmode='cube' : Spectral line imaging with one or more channels.
420 421 Parameters start, width,and nchan define the spectral
421 422 coordinate system and can be specified either in terms
422 423 of channel numbers, frequency or velocity in whatever
423 424 spectral frame is specified in 'outframe'.
424 425 All internal and output images are made with outframe as the
425 426 base spectral frame. However imaging code internally uses the fixed
426 427 spectral frame, LSRK for automatic internal software
427 - Doppler tracking so that a spectral line observed over an
428 + Doppler correction, so that a spectral line observed over an
428 429 extended time range will line up appropriately.
429 430 Therefore the output images have additional spectral frame conversion
430 431 layer in LSRK on the top the base frame.
431 432 ​
432 -​
433 - (Note : Even if the input parameters are specified in a frame
434 - other than LSRK, the viewer still displays spectral
435 - axis in LSRK by default because of the conversion frame
436 - layer mentioned above. The viewer can be used to relabel
437 - the spectral axis in any desired frame - via the spectral
438 - reference option under axis label properties in the
439 - data display options window.)
440 -​
441 -​
442 433
443 434 ​
444 435 ​
445 - specmode='cubedata' : Spectral line imaging with one or more channels
446 - There is no internal software Doppler tracking so
436 + specmode='cubedata' : Spectral line imaging with one or more channels.
437 + There is no internal software Doppler correction, so
447 438 a spectral line observed over an extended time range
448 439 may be smeared out in frequency. There is strictly
449 440 no valid spectral frame with which to associate with the
450 441 output images, thus the image spectral frame will
451 442 be labelled &quot;Undefined&quot;.
452 443 ​
453 444
454 445 specmode='cubesource': Spectral line imaging while
455 446 tracking moving source (near field or solar system
456 447 objects). The velocity of the source is accounted
457 448 and the frequency reported is in the source frame.
458 449 As there is no &quot;SOURCE&quot; frame defined in CASA,
459 450 the frame in the image will be labelled &quot;REST&quot; (but do note the
460 451 velocity of a given line reported may be different from the rest frame
461 452 velocity if the emission region is moving w.r.t the systemic
462 - velocity frame of the source)
453 + velocity frame of the source).
463 454 ​
464 455 specmode='mvc' : Multiterm continuum imaging with cube major cycles.
465 456 This mode requires deconvolver='mtmfs' with nterms>1
466 457 and user-set choices of 'reffreq' and 'nchan'.
467 458 ​
468 459 The output images and minor cycle are similar to specmode='mfs'
469 460 with deconvolver='mtmfs', but the major cycles are done in
470 461 cube mode (and require a setting of 'reffreq' and 'nchan').
471 462 By default, frequency-dependent primary beam correction is
472 463 applied to each channel, before being combined across frequency
512 503 <value>cont</value>
513 504 <value>cube</value>
514 505 <value>cubedata</value>
515 506 <value>cubesource</value>
516 507 <value>mvc</value>
517 508 </allowed>
518 509 </param>
519 510 ​
520 511 <param type="any" name="reffreq" subparam="true">
521 512 <shortdescription>Reference frequency</shortdescription>
522 -<description>Reference frequency of the output image coordinate system
513 +<description>Reference frequency of the output image coordinate system.
523 514 ​
524 515 Example : reffreq='1.5GHz' as a string with units.
525 516 ​
526 517 By default, it is calculated as the middle of the selected frequency range.
527 518 ​
528 519 For deconvolver='mtmfs' the Taylor expansion is also done about
529 520 this specified reference frequency.
530 521 ​
531 522 </description>
532 523 <value type="string"/>
533 524 </param>
534 525 ​
535 526 <param type="int" name="nchan" subparam="true">
536 527 <shortdescription>Number of channels in the output image</shortdescription>
537 -<description>Number of channels in the output image
528 +<description>Number of channels in the output image.
538 529 For default (=-1), the number of channels will be automatically determined
539 530 based on data selected by 'spw' with 'start' and 'width'.
540 531 It is often easiest to leave nchan at the default value.
541 532 example: nchan=100
542 533 ​
543 534 </description>
544 535 <value type="int">-1</value>
545 536 </param>
546 537 ​
547 538 <param type="any" name="start" subparam="true">
555 546 Since the integer number in 'start' represents the data channel number,
556 547 when the channel number is used along with the spectral window id selection
557 548 in 'spw', 'start' specified as an integer should be carefully set otherwise
558 549 it may result in the blank image channels if the 'start' channel (i.e. absolute
559 550 channel number) is outside of the channel range specified in 'spw'.
560 551 In such a case, 'start' can be left as a default (='') to ensure
561 552 matching with the data spectral channel selection.
562 553 For specmode='cube', when velocity or frequency is used it is
563 554 interpreted with the frame defined in outframe. [The parameters of
564 555 the desired output cube can be estimated by using the 'transform'
565 - functionality of 'plotms']
566 - examples: start='5.0km/s'; 1st channel, 5.0km/s in outframe
567 - start='22.3GHz'; 1st channel, 22.3GHz in outframe
556 + functionality of 'plotms'].
557 + examples: start='5.0km/s'; 1st channel, 5.0km/s in outframe.
558 + start='22.3GHz'; 1st channel, 22.3GHz in outframe.
568 559 </description>
569 560 <value type="string"/>
570 561 </param>
571 562 ​
572 563 <param type="any" name="width" subparam="true">
573 564 <shortdescription>Channel width (e.g. width=2,width=\'0.1MHz\',width=\'10km/s\')</shortdescription>
574 565 <description>Channel width (e.g. width=2,width=\'0.1MHz\',width=\'10km/s\') of output cube images
575 566 specified by data channel number (integer), velocity (string with a unit), or
576 567 or frequency (string with a unit).
577 - Default:''; data channel width
568 + Default:''; data channel width.
578 569 The sign of width defines the direction of the channels to be incremented.
579 570 For width specified in velocity or frequency with '-' in front gives image channels in
580 571 decreasing velocity or frequency, respectively.
581 572 For specmode='cube', when velocity or frequency is used it is interpreted with
582 573 the reference frame defined in outframe.
583 - examples: width='2.0km/s'; results in channels with increasing velocity
584 - width='-2.0km/s'; results in channels with decreasing velocity
585 - width='40kHz'; results in channels with increasing frequency
574 + examples: width='2.0km/s'; results in channels with increasing velocity.
575 + width='-2.0km/s'; results in channels with decreasing velocity.
576 + width='40kHz'; results in channels with increasing frequency.
586 577 width=-2; results in channels averaged of 2 data channels incremented from
587 - high to low channel numbers
578 + high to low channel numbers.
588 579 ​
589 580 </description>
590 581 <value type="string"/>
591 582 </param>
592 583 ​
593 584 <param type="string" name="outframe" subparam="true">
594 585 <shortdescription>Spectral reference frame in which to interpret \'start\' and \'width\'</shortdescription>
595 586 <description>Spectral reference frame in which to interpret \'start\' and \'width\'
596 587 Options: '','LSRK','LSRD','BARY','GEO','TOPO','GALACTO','LGROUP','CMB'
597 - example: outframe='bary' for Barycentric frame
598 -​
599 - REST -- Rest frequency
600 - LSRD -- Local Standard of Rest (J2000)
601 - -- as the dynamical definition (IAU, [9,12,7] km/s in galactic coordinates)
602 - LSRK -- LSR as a kinematical (radio) definition
603 - -- 20.0 km/s in direction ra,dec = [270,+30] deg (B1900.0)
604 - BARY -- Barycentric (J2000)
605 - GEO --- Geocentric
606 - TOPO -- Topocentric
588 + example: outframe='bary' for Barycentric frame.
589 +​
590 + REST -- Rest frequency.
591 + LSRD -- Local Standard of Rest (J2000).
592 + -- as the dynamical definition (IAU, [9,12,7] km/s in galactic coordinates).
593 + LSRK -- LSR as a kinematical (radio) definition.
594 + -- 20.0 km/s in direction ra,dec = [270,+30] deg (B1900.0).
595 + BARY -- Barycentric (J2000).
596 + GEO --- Geocentric.
597 + TOPO -- Topocentric.
607 598 GALACTO -- Galacto centric (with rotation of 220 km/s in direction l,b = [90,0] deg.
608 - LGROUP -- Local group velocity -- 308km/s towards l,b = [105,-7] deg (F. Ghigo)
609 - CMB -- CMB velocity -- 369.5km/s towards l,b = [264.4, 48.4] deg (F. Ghigo)
610 - DEFAULT = LSRK
599 + LGROUP -- Local group velocity -- 308km/s towards l,b = [105,-7] deg (F. Ghigo).
600 + CMB -- CMB velocity -- 369.5km/s towards l,b = [264.4, 48.4] deg (F. Ghigo).
601 + DEFAULT = LSRK.
611 602 ​
612 603 </description>
613 604 <value type="string">LSRK</value>
614 605 </param>
615 606 ​
616 607 <param type="string" name="veltype" subparam="true">
617 608 <shortdescription>Velocity type (radio, z, ratio, beta, gamma, optical)</shortdescription>
618 609 <description>Velocity type (radio, z, ratio, beta, gamma, optical)
619 - For start and/or width specified in velocity, specifies the velocity definition
610 + For 'start' and/or 'width' specified in velocity, specifies the velocity definition
620 611 Options: 'radio','optical','z','beta','gamma','optical'
621 612 NOTE: the viewer always defaults to displaying the 'radio' frame,
622 613 but that can be changed in the position tracking pull down.
623 614 ​
624 615 The different types (with F = f/f0, the frequency ratio), are:
625 616 ​
626 - Z = (-1 + 1/F)
627 - RATIO = (F) \*
628 - RADIO = (1 - F)
629 - OPTICAL == Z
630 - BETA = ((1 - F2)/(1 + F2))
631 - GAMMA = ((1 + F2)/2F) \*
632 - RELATIVISTIC == BETA (== v/c)
633 - DEFAULT == RADIO
617 + Z = (-1 + 1/F).
618 + RATIO = (F) \*.
619 + RADIO = (1 - F).
620 + OPTICAL == Z.
621 + BETA = ((1 - F^2)/(1 + F^2)).
622 + GAMMA = ((1 + F^2)/2F) \*.
623 + RELATIVISTIC == BETA (== v/c).
624 + DEFAULT == RADIO.
634 625 Note that the ones with an '\*' have no real interpretation
635 626 (although the calculation will proceed) if given as a velocity.
636 627 ​
637 628 </description>
638 629 <value type="string">radio</value>
639 630 </param>
640 631 ​
641 632 <param type="any" name="restfreq" subparam="true">
642 633 <shortdescription>List of rest frequencies</shortdescription>
643 634 <description>List of rest frequencies or a rest frequency in a string.
644 635 Specify rest frequency to use for output image.
645 - \*Currently it uses the first rest frequency in the list for translation of
636 +​
637 + Currently it uses the first rest frequency in the list for translation of
646 638 velocities. The list will be stored in the output images.
647 639 Default: []; look for the rest frequency stored in the MS, if not available,
648 - use center frequency of the selected channels
649 - examples: restfreq=['1.42GHz']
650 - restfreq='1.42GHz'
640 + use center frequency of the selected channels.
641 + examples: restfreq=['1.42GHz'].
642 + restfreq='1.42GHz'.
651 643 ​
652 644 </description>
653 645 <value type="stringVec"/>
654 646 </param>
655 647 ​
656 648 ​
657 649 ​
658 650 <param type="string" name="interpolation" subparam="true">
659 651 <shortdescription>Spectral interpolation (nearest,linear,cubic)</shortdescription>
660 652 <description>Spectral interpolation (nearest,linear,cubic)
742 734 <description>Gridding options (standard, wproject, widefield, mosaic, awproject)
743 735 ​
744 736 The following options choose different gridding convolution
745 737 functions for the process of convolutional resampling of the measured
746 738 visibilities onto a regular uv-grid prior to an inverse FFT.
747 739 Model prediction (degridding) also uses these same functions.
748 740 Several wide-field effects can be accounted for via careful choices of
749 741 convolution functions. Gridding (degridding) runtime will rise in
750 742 proportion to the support size of these convolution functions (in uv-pixels).
751 743 ​
752 - standard : Prolate Spheroid with 7x7 uv pixel support size
744 + standard : Prolate Spheroid with 7x7 uv pixel support size.
753 745 ​
754 746 [ This mode can also be invoked using 'ft' or 'gridft' ]
755 747 ​
756 748 wproject : W-Projection algorithm to correct for the widefield
757 749 non-coplanar baseline effect. [Cornwell et.al 2008]
758 750 ​
759 751 wprojplanes is the number of distinct w-values at
760 752 which to compute and use different gridding convolution
761 753 functions (see help for wprojplanes).
762 754 Convolution function support size can range
766 758 ​
767 759 widefield : Facetted imaging with or without W-Projection per facet.
768 760 ​
769 761 A set of facets x facets subregions of the specified image
770 762 are gridded separately using their respective phase centers
771 763 (to minimize max W). Deconvolution is done on the joint
772 764 full size image, using a PSF from the first subregion.
773 765 ​
774 766 wprojplanes=1 : standard prolate spheroid gridder per facet.
775 767 wprojplanes &gt; 1 : W-Projection gridder per facet.
776 - nfacets=1, wprojplanes &gt; 1 : Pure W-Projection and no facetting
777 - nfacets=1, wprojplanes=1 : Same as standard,ft,gridft
768 + nfacets=1, wprojplanes &gt; 1 : Pure W-Projection and no facetting.
769 + nfacets=1, wprojplanes=1 : Same as standard,ft,gridft.
778 770 ​
779 771 A combination of facetting and W-Projection is relevant only for
780 772 very large fields of view. (In our current version of tclean, this
781 773 combination runs only with parallel=False.
782 774 ​
783 775 mosaic : A-Projection with azimuthally symmetric beams without
784 776 sidelobes, beam rotation or squint correction.
785 777 Gridding convolution functions per visibility are computed
786 778 from FTs of PB models per antenna.
787 779 This gridder can be run on single fields as well as mosaics.
788 780 ​
789 - VLA : PB polynomial fit model (Napier and Rots, 1982)
790 - EVLA : PB polynomial fit model (Perley, 2015)
781 + VLA : PB polynomial fit model (Napier and Rots, 1982).
782 + EVLA : PB polynomial fit model (Perley, 2015).
791 783 ALMA : Airy disks for a 10.7m dish (for 12m dishes) and
792 784 6.25m dish (for 7m dishes) each with 0.75m
793 785 blockages (Hunter/Brogan 2011). Joint mosaic
794 786 imaging supports heterogeneous arrays for ALMA.
795 787 ​
796 788 Typical gridding convolution function support sizes are
797 789 between 7 and 50 depending on the desired
798 790 accuracy (given by the uv cell size or image field of view).
799 791 ​
800 792 [ This mode can also be invoked using 'mosaicft' or 'ftmosaic' ]
805 797 [Bhatnagar et.al, 2008]
806 798 ​
807 799 Gridding convolution functions are computed from
808 800 aperture illumination models per antenna and optionally
809 801 combined with W-Projection kernels and a prolate spheroid.
810 802 This gridder can be run on single fields as well as mosaics.
811 803 ​
812 804 VLA : Uses ray traced model (VLA and EVLA) including feed
813 805 leg and subreflector shadows, off-axis feed location
814 806 (for beam squint and other polarization effects), and
815 - a Gaussian fit for the feed beams (Ref: Brisken 2009)
807 + a Gaussian fit for the feed beams (Brisken 2009)
816 808 ALMA : Similar ray-traced model as above (but the correctness
817 809 of its polarization properties remains un-verified).
818 810 ​
819 811 Typical gridding convolution function support sizes are
820 812 between 7 and 50 depending on the desired
821 813 accuracy (given by the uv cell size or image field of view).
822 814 When combined with W-Projection they can be significantly larger.
823 815 ​
824 816 [ This mode can also be invoked using 'awprojectft' ]
825 817 ​
826 - imagemosaic : (untested implementation)
818 + imagemosaic : (untested implementation).
827 819 Grid and iFT each pointing separately and combine the
828 820 images as a linear mosaic (weighted by a PB model) in
829 821 the image domain before a joint minor cycle.
830 822 ​
831 - VLA/ALMA PB models are same as for gridder='mosaicft'
823 + VLA/ALMA PB models are same as for gridder='mosaicft'.
832 824 ​
833 825 ------ Notes on PB models :
834 826 ​
835 827 (1) Several different sources of PB models are used in the modes
836 828 listed above. This is partly for reasons of algorithmic flexibility
837 829 and partly due to the current lack of a common beam model
838 830 repository or consensus on what beam models are most appropriate.
839 831 ​
840 832 (2) For ALMA and gridder='mosaic', ray-traced (TICRA) beams
841 833 are also available via the vpmanager tool.
857 849 (which needs a 1/0 mask). There are two options for making a pb based
858 850 deconvolution mask.
859 851 -- Run tclean with niter=0 to produce the .pb, construct a 1/0 image
860 852 with the desired threshold (using ia.open('newmask.im');
861 853 ia.calc('iif(&quot;xxx.pb&quot;&gt;0.3,1.0,0.0)');ia.close() for example),
862 854 and supply it via the 'mask' parameter in a subsequent run
863 855 (with calcres=F and calcpsf=F to restart directly from the minor cycle).
864 856 -- Run tclean with usemask='pb' for it to automatically construct
865 857 a 1/0 mask from the internal T/F mask from .pb at a fixed 0.2 threshold.
866 858 ​
867 - ----- Making PBs for gridders other than mosaic,awproject
859 + ----- Making PBs for gridders other than mosaic,awproject.
868 860 ​
869 861 After the PSF generation, a PB is constructed using the same
870 862 models used in gridder='mosaic' but just evaluated in the image
871 863 domain without consideration to weights.
872 864 ​
873 865 </description>
874 866 <value type="string">standard</value>
875 867 <allowed kind="enum">
876 868 <value>standard</value>
877 869 <value>ft</value>
911 903 optional direction. You may need to use
912 904 this if for example the mosaic does not
913 905 have any pointing in the center of the
914 906 image. Another reason; as the psf is
915 907 approximate for a mosaic, this may help
916 908 to deconvolve a non central bright source
917 909 well and quickly.
918 910 ​
919 911 example:
920 912 ​
921 - psfphasecenter=6 #center psf on field 6
922 - psfphasecenter='J2000 19h30m00 -40d00m00'
923 - psfphasecenter='J2000 292.5deg -40.0deg'
924 - psfphasecenter='J2000 5.105rad -0.698rad'
925 - psfphasecenter='ICRS 13:05:27.2780 -049.28.04.458'
913 + psfphasecenter='6' #center psf on field 6.
914 + psfphasecenter='J2000 19h30m00 -40d00m00'.
915 + psfphasecenter='J2000 292.5deg -40.0deg'.
916 + psfphasecenter='J2000 5.105rad -0.698rad'.
917 + psfphasecenter='ICRS 13:05:27.2780 -049.28.04.458'.
926 918 </description>
927 919 <type>int</type><type>string</type>
928 920 <value type="string"/>
929 921 </param>
930 922 ​
931 923 <param type="int" name="wprojplanes" subparam="true">
932 924 <shortdescription>Number of distinct w-values for convolution functions</shortdescription>
933 925 <description>Number of distinct w-values at which to compute and use different
934 926 gridding convolution functions for W-Projection
935 927 ​
956 948 in which the number of planes is automatically computed.
957 949 ​
958 950 </description>
959 951 <value type="int">1</value>
960 952 </param>
961 953 ​
962 954 <param type="string" name="vptable" subparam="true">
963 955 <shortdescription>Name of Voltage Pattern table</shortdescription>
964 956 <description> VP table saved via the vpmanager
965 957 ​
966 - vptable=&quot;&quot; : Choose default beams for different telescopes
967 - ALMA : Airy disks
958 + vptable=&quot;&quot; : Choose default beams for different telescopes.
959 + ALMA : Airy disks.
968 960 EVLA : old VLA models.
969 961 ​
970 962 Other primary beam models can be chosen via the vpmanager tool.
971 963 ​
972 - Step 1 : Set up the vpmanager tool and save its state in a table
964 + Step 1 : Set up the vpmanager tool and save its state in a table.
973 965 ​
974 966 vp.setpbpoly(telescope='EVLA', coeff=[1.0, -1.529e-3, 8.69e-7, -1.88e-10])
975 967 vp.saveastable('myvp.tab')
976 968 ​
977 969 Step 2 : Supply the name of that table in tclean.
978 970 ​
979 971 tclean(....., vptable='myvp.tab',....)
980 972 ​
981 973 Please see the documentation for the vpmanager for more details on how to
982 974 choose different beam models. Work is in progress to update the defaults
991 983 <value type="string"/>
992 984 </param>
993 985 <param type="bool" name="mosweight" subparam="true">
994 986 <shortdescription>Indepently weight each field in a mosaic</shortdescription>
995 987 <description>When doing Brigg's style weighting (including uniform) to perform the weight density calculation for each field indepedently if True. If False the weight density is calculated from the average uv distribution of all the fields.
996 988 </description>
997 989 <value type="bool">True</value>
998 990 </param>
999 991 <param type="bool" name="aterm" subparam="true">
1000 992 <shortdescription>Use aperture illumination functions during gridding</shortdescription>
1001 -<description>Use aperture illumination functions during gridding
993 +<description>Use aperture illumination functions during gridding.
1002 994 ​
1003 995 This parameter turns on the A-term of the AW-Projection gridder.
1004 996 Gridding convolution functions are constructed from aperture illumination
1005 997 function models of each antenna.
1006 998 ​
1007 999 </description>
1008 1000 <value type="bool">True</value>
1009 1001 </param>
1010 1002 ​
1011 1003 <param type="bool" name="psterm" subparam="true">
1012 1004 <shortdescription>Use prolate spheroidal during gridding</shortdescription>
1013 1005 <description>Include the Prolate Spheroidal (PS) funtion as the anti-aliasing
1014 1006 operator in the gridding convolution functions used for gridding.
1015 1007 ​
1016 1008 Setting this parameter to true is necessary when aterm is set to
1017 1009 false. It can be set to false when aterm is set to true, though
1018 1010 with this setting effects of aliasing may be there in the image,
1019 1011 particularly near the edges.
1020 1012 ​
1021 1013 When set to true, the .pb images will contain the fourier transform
1022 - of the of the PS funtion. The table below enumarates the functional
1023 - effects of the psterm, aterm and wprojplanes settings. PB referes to
1024 - the Primary Beam and FT() refers to the Fourier transform operation.
1014 + of the of the PS funtion.
1025 1015 ​
1026 - Operation aterm psterm wprojplanes Contents of the .pb image
1027 - ----------------------------------------------------------------------
1028 - AW-Projection True True &gt;1 FT(PS) x PB
1029 - False PB
1016 + For more information on the functional
1017 + effects of the psterm, aterm and wprojplanes settings, see the
1018 + 'Wide-field Imaging' pages in CASA Docs (https://casadocs.readthedocs.io).
1030 1019 ​
1031 - A-Projection True True 1 FT(PS) x PB
1032 - False PB
1033 -​
1034 - W-Projection False True &gt;1 FT(PS)
1035 -​
1036 - Standard False True 1 FT(PS)
1037 1020 ​
1038 1021 </description>
1039 1022 <value type="bool">False</value>
1040 1023 </param>
1041 1024 ​
1042 1025 <param type="bool" name="wbawp" subparam="true">
1043 1026 <shortdescription>Use wideband A-terms</shortdescription>
1044 -<description>Use frequency dependent A-terms
1027 +<description>Use frequency dependent A-terms.
1045 1028 Scale aperture illumination functions appropriately with frequency
1046 1029 when gridding and combining data from multiple channels.
1047 1030 </description>
1048 1031 <value type="bool">True</value>
1049 1032 </param>
1050 1033 ​
1051 1034 <param type="bool" name="conjbeams" subparam="true">
1052 1035 <shortdescription>Use conjugate frequency for wideband A-terms</shortdescription>
1053 -<description>Use conjugate frequency for wideband A-terms
1036 +<description>Use conjugate frequency for wideband A-terms.
1054 1037 ​
1055 1038 While gridding data from one frequency channel, choose a convolution
1056 1039 function from a 'conjugate' frequency such that the resulting baseline
1057 1040 primary beam is approximately constant across frequency. For a system in
1058 1041 which the primary beam scales with frequency, this step will eliminate
1059 1042 instrumental spectral structure from the measured data and leave only the
1060 1043 sky spectrum for the minor cycle to model and reconstruct [Bhatnagar et al., ApJ, 2013].
1061 1044 ​
1062 1045 As a rough guideline for when this is relevant, a source at the half power
1063 1046 point of the PB at the center frequency will see an artificial spectral
1064 1047 index of -1.4 due to the frequency dependence of the PB [Sault and Wieringa, 1994].
1065 1048 If left uncorrected during gridding, this spectral structure must be modeled
1066 1049 in the minor cycle (using the mtmfs algorithm) to avoid dynamic range limits
1067 1050 (of a few hundred for a 2:1 bandwidth).
1068 - This works for specmode='mfs' and its value is ignored for cubes
1051 + This works for specmode='mfs' and its value is ignored for cubes.
1069 1052 ​
1070 1053 </description>
1071 1054 <value type="bool">False</value>
1072 1055 </param>
1073 1056 ​
1074 1057 <param type="string" name="cfcache" subparam="true">
1075 1058 <shortdescription>Convolution function cache directory name</shortdescription>
1076 -<description>Convolution function cache directory name
1059 +<description>Convolution function cache directory name.
1077 1060 ​
1078 1061 Name of a directory in which to store gridding convolution functions.
1079 1062 This cache is filled at the beginning of an imaging run. This step can be time
1080 1063 consuming but the cache can be reused across multiple imaging runs that
1081 1064 use the same image parameters (cell size, image size , spectral data
1082 1065 selections, wprojplanes, wbawp, psterm, aterm). The effect of the wbawp,
1083 1066 psterm and aterm settings is frozen-in in the cfcache. Using an existing cfcache
1084 1067 made with a different setting of these parameters will not reflect the current
1085 1068 settings.
1086 1069 ​
1098 1081 ​
1099 1082 <param type="bool" name="usepointing" subparam="true">
1100 1083 <shortdescription>The parameter makes the gridder utilize the pointing table phase directions while computing the residual image.</shortdescription>
1101 1084 <description>The usepointing flag informs the gridder that it should utilize the pointing table
1102 1085 to use the correct direction in which the antenna is pointing with respect to the pointing phasecenter. </description>
1103 1086 <value type="bool">False</value>
1104 1087 </param>
1105 1088 ​
1106 1089 <param type="double" name="computepastep" subparam="true">
1107 1090 <shortdescription>Parallactic angle interval after the AIFs are recomputed (deg)</shortdescription>
1108 -<description>Parallactic angle interval after the AIFs are recomputed (deg)
1091 +<description>Parallactic angle interval after the AIFs are recomputed (deg).
1109 1092 ​
1110 1093 This parameter controls the accuracy of the aperture illumination function
1111 1094 used with AProjection for alt-az mount dishes where the AIF rotates on the
1112 1095 sky as the synthesis image is built up. Once the PA in the data changes by
1113 1096 the given interval, AIFs are re-computed at the new PA.
1114 1097 ​
1115 1098 A value of 360.0 deg (the default) implies no re-computation due to PA rotation.
1116 1099 AIFs are computed for the PA value of the first valid data received and used for
1117 1100 all of the data.
1118 1101 ​
1200 1183 ​
1201 1184 </description>
1202 1185 <type>intVec</type><type>doubleVec</type>
1203 1186 <value type="doubleVec"/>
1204 1187 </param>
1205 1188
1206 1189
1207 1190 ​
1208 1191 <param type="double" name="pblimit" subparam="true">
1209 1192 <shortdescription>PB gain level at which to cut off normalizations </shortdescription>
1210 -<description>PB gain level at which to cut off normalizations
1193 +<description>PB gain level at which to cut off normalizations.
1211 1194 ​
1212 1195 Divisions by .pb during normalizations have a cut off at a .pb gain
1213 1196 level given by pblimit. Outside this limit, image values are set to zero.
1214 1197 Additionally, by default, an internal T/F mask is applied to the .pb, .image and
1215 1198 .residual images to mask out (T) all invalid pixels outside the pblimit area.
1216 1199 ​
1217 1200 Note : This internal T/F mask cannot be used as a deconvolution mask.
1218 1201 To do so, please follow the steps listed above in the Notes for the
1219 1202 'gridder' parameter.
1220 1203 ​
1232 1215 ia.open('test.image');
1233 1216 ia.maskhandler(op='set', name='');
1234 1217 ia.done()
1235 1218 ​
1236 1219 </description>
1237 1220 <value type="double">0.2</value>
1238 1221 </param>
1239 1222 ​
1240 1223 <param type="string" name="normtype" subparam="true">
1241 1224 <shortdescription>Normalization type (flatnoise, flatsky,pbsquare)</shortdescription>
1242 -<description>Normalization type (flatnoise, flatsky, pbsquare)
1225 +<description>Normalization type (flatnoise, flatsky, pbsquare).
1243 1226 ​
1244 1227 Gridded (and FT'd) images represent the PB-weighted sky image.
1245 1228 Qualitatively it can be approximated as two instances of the PB
1246 1229 applied to the sky image (one naturally present in the data
1247 1230 and one introduced during gridding via the convolution functions).
1248 1231 ​
1249 1232 xxx.weight : Weight image approximately equal to sum ( square ( pb ) )
1250 1233 xxx.pb : Primary beam calculated as sqrt ( xxx.weight )
1251 1234 ​
1252 1235 normtype='flatnoise' : Divide the raw image by sqrt(.weight) so that
1270 1253 ​
1271 1254 ​
1272 1255 ​
1273 1256 ​
1274 1257 ​
1275 1258 ​
1276 1259 <param type="string" name="deconvolver">
1277 1260 <shortdescription>Minor cycle algorithm (hogbom,clark,multiscale,mtmfs,mem,clarkstokes,asp)</shortdescription>
1278 1261 <description>Name of minor cycle algorithm (hogbom,clark,multiscale,mtmfs,mem,clarkstokes,asp)
1279 1262 ​
1280 - Each of the following algorithms operate on residual images and psfs
1263 + Each of the following algorithms operate on residual images and PSFs
1281 1264 from the gridder and produce output model and restored images.
1282 1265 Minor cycles stop and a major cycle is triggered when cyclethreshold
1283 1266 or cycleniter are reached. For all methods, components are picked from
1284 1267 the entire extent of the image or (if specified) within a mask.
1285 1268 ​
1286 - hogbom : An adapted version of Hogbom Clean [Hogbom, 1974]
1287 - - Find the location of the peak residual
1288 - - Add this delta function component to the model image
1269 + hogbom : An adapted version of Hogbom Clean [Hogbom, 1974].
1270 + - Find the location of the peak residual.
1271 + - Add this delta function component to the model image.
1289 1272 - Subtract a scaled and shifted PSF of the same size as the image
1290 1273 from regions of the residual image where the two overlap.
1291 - - Repeat
1274 + - Repeat.
1292 1275 ​
1293 - clark : An adapted version of Clark Clean [Clark, 1980]
1294 - - Find the location of max(I^2+Q^2+U^2+V^2)
1295 - - Add delta functions to each stokes plane of the model image
1276 + clark : An adapted version of Clark Clean [Clark, 1980].
1277 + - Find the location of max(I^2+Q^2+U^2+V^2).
1278 + - Add delta functions to each stokes plane of the model image.
1296 1279 - Subtract a scaled and shifted PSF within a small patch size
1297 1280 from regions of the residual image where the two overlap.
1298 1281 - After several iterations trigger a Clark major cycle to subtract
1299 1282 components from the visibility domain, but without de-gridding.
1300 - - Repeat
1283 + - Repeat.
1301 1284 ​
1302 1285 ( Note : 'clark' maps to imagermode='' in the old clean task.
1303 1286 'clark_exp' is another implementation that maps to
1304 1287 imagermode='mosaic' or 'csclean' in the old clean task
1305 1288 but the behavior is not identical. For now, please
1306 1289 use deconvolver='hogbom' if you encounter problems. )
1307 1290 ​
1308 - clarkstokes : Clark Clean operating separately per Stokes plane
1291 + clarkstokes : Clark Clean operating separately per Stokes plane.
1309 1292 ​
1310 1293 (Note : 'clarkstokes_exp' is an alternate version. See above.)
1311 1294 ​
1312 - multiscale : MultiScale Clean [Cornwell, 2008]
1313 - - Smooth the residual image to multiple scale sizes
1314 - - Find the location and scale at which the peak occurs
1315 - - Add this multiscale component to the model image
1295 + multiscale : MultiScale Clean [Cornwell, 2008].
1296 + - Smooth the residual image to multiple scale sizes.
1297 + - Find the location and scale at which the peak occurs.
1298 + - Add this multiscale component to the model image.
1316 1299 - Subtract a scaled,smoothed,shifted PSF (within a small
1317 - patch size per scale) from all residual images
1318 - - Repeat from step 2
1300 + patch size per scale) from all residual images.
1301 + - Repeat from step 2.
1319 1302 ​
1320 - mtmfs : Multi-term (Multi Scale) Multi-Frequency Synthesis [Rau and Cornwell, 2011]
1321 - - Smooth each Taylor residual image to multiple scale sizes
1303 + mtmfs : Multi-term (Multi Scale) Multi-Frequency Synthesis [Rau and Cornwell, 2011].
1304 + - Smooth each Taylor residual image to multiple scale sizes.
1322 1305 - Solve a NTxNT system of equations per scale size to compute
1323 - Taylor coefficients for components at all locations
1306 + Taylor coefficients for components at all locations.
1324 1307 - Compute gradient chi-square and pick the Taylor coefficients
1325 1308 and scale size at the location with maximum reduction in
1326 - chi-square
1309 + chi-square.
1327 1310 - Add multi-scale components to each Taylor-coefficient
1328 - model image
1311 + model image.
1329 1312 - Subtract scaled,smoothed,shifted PSF (within a small patch size
1330 - per scale) from all smoothed Taylor residual images
1331 - - Repeat from step 2
1313 + per scale) from all smoothed Taylor residual images.
1314 + - Repeat from step 2.
1332 1315 ​
1333 1316 ​
1334 - mem : Maximum Entropy Method [Cornwell and Evans, 1985]
1317 + mem : Maximum Entropy Method [Cornwell and Evans, 1985].
1335 1318 - Iteratively solve for values at all individual pixels via the
1336 1319 MEM method. It minimizes an objective function of
1337 1320 chi-square plus entropy (here, a measure of difference
1338 1321 between the current model and a flat prior model).
1339 1322 ​
1340 1323 (Note : This MEM implementation is not very robust.
1341 1324 Improvements will be made in the future.)
1342 1325 ​
1343 - asp : Adaptive Scale Pixel algorithm [Bhatnagar and Cornwell, 2004]
1344 - - Define a set of initial scales defined as 0, W, 2W 4W and 8W
1345 - where W is a 2D Gaussian fitting width to the PSF
1346 - - Smooth the residual image by a Gaussian beam at initial scales
1347 - - Search for the global peak (F) among these smoothed residual images
1348 - - form an active Aspen set: amplitude(F), amplitude location(x,y)
1326 + asp : Adaptive Scale Pixel algorithm [Bhatnagar and Cornwell, 2004].
1327 + - Define a set of initial scales defined as 0, W, 2W 4W and 8W.
1328 + where W is a 2D Gaussian fitting width to the PSF.
1329 + - Smooth the residual image by a Gaussian beam at initial scales.
1330 + - Search for the global peak (F) among these smoothed residual images.
1331 + - form an active Aspen set: amplitude(F), amplitude location(x,y).
1349 1332 - Optimize the Aspen set by minimizing the objective function RI-Aspen*PSF,
1350 1333 where RI is the residual image and * is the convulition operation.
1351 1334 - Compute the model image and update the residual image
1352 1335 - Repeat from step 2
1353 1336 ​
1354 1337 ​
1355 1338 </description>
1356 1339 <value type="string">hogbom</value>
1357 1340 <allowed kind="enum">
1358 1341 <value>hogbom</value>
1370 1353 ​
1371 1354 <param type="any" name="scales" subparam="true">
1372 1355 <shortdescription>List of scale sizes (in pixels) for multi-scale algorithms</shortdescription>
1373 1356 <description>List of scale sizes (in pixels) for multi-scale and mtmfs algorithms.
1374 1357 --&gt; scales=[0,6,20]
1375 1358 This set of scale sizes should represent the sizes
1376 1359 (diameters in units of number of pixels)
1377 1360 of dominant features in the image being reconstructed.
1378 1361 ​
1379 1362 The smallest scale size is recommended to be 0 (point source),
1380 - the second the size of the synthesized beam and the third 3-5
1363 + the second being the size of the synthesized beam and the third being 3-5
1381 1364 times the synthesized beam, etc. For example, if the synthesized
1382 1365 beam is 10&quot; FWHM and cell=2&quot;,try scales = [0,5,15].
1383 1366 ​
1384 1367 For numerical stability, the largest scale must be
1385 1368 smaller than the image (or mask) size and smaller than or
1386 1369 comparable to the scale corresponding to the lowest measured
1387 1370 spatial frequency (as a scale size much larger than what the
1388 1371 instrument is sensitive to is unconstrained by the data making
1389 - it harder to recovery from errors during the minor cycle).
1372 + it harder to recover from errors during the minor cycle).
1390 1373 </description>
1391 1374 <type>intVec</type><type>doubleVec</type>
1392 1375 <value type="intVec"/>
1393 1376 </param>
1394 1377 ​
1395 1378 <param type="int" name="nterms" subparam="true">
1396 1379 <shortdescription>Number of Taylor coefficients in the spectral model</shortdescription>
1397 -<description>Number of Taylor coefficients in the spectral model
1380 +<description>Number of Taylor coefficients in the spectral model.
1398 1381 ​
1399 - - nterms=1 : Assume flat spectrum source
1400 - - nterms=2 : Spectrum is a straight line with a slope
1401 - - nterms=N : A polynomial of order N-1
1382 + - nterms=1 : Assume flat spectrum source.
1383 + - nterms=2 : Spectrum is a straight line with a slope.
1384 + - nterms=N : A polynomial of order N-1.
1402 1385 ​
1403 1386 From a Taylor expansion of the expression of a power law, the
1404 - spectral index is derived as alpha = taylorcoeff_1 / taylorcoeff_0
1387 + spectral index is derived as alpha = taylorcoeff_1 / taylorcoeff_0.
1405 1388 ​
1406 1389 Spectral curvature is similarly derived when possible.
1407 1390 ​
1408 1391 The optimal number of Taylor terms depends on the available
1409 1392 signal to noise ratio, bandwidth ratio, and spectral shape of the
1410 1393 source as seen by the telescope (sky spectrum x PB spectrum).
1411 1394 ​
1412 1395 nterms=2 is a good starting point for wideband EVLA imaging
1413 1396 and the lower frequency bands of ALMA (when fractional bandwidth
1414 1397 is greater than 10%) and if there is at least one bright source for
1427 1410 - These alpha, alpha.error and beta images contain
1428 1411 internal T/F masks based on a threshold computed
1429 1412 as peakresidual/10. Additional masking based on
1430 1413 .alpha/.alpha.error may be desirable.
1431 1414 - .alpha.error is a purely empirical estimate derived
1432 1415 from the propagation of error during the division of
1433 1416 two noisy numbers (alpha = xx.tt1/xx.tt0) where the
1434 1417 'error' on tt1 and tt0 are simply the values picked from
1435 1418 the corresponding residual images. The absolute value
1436 1419 of the error is not always accurate and it is best to interpret
1437 - the errors across the image only in a relative sense.)
1420 + the errors across the image only in a relative sense.
1438 1421 ​
1439 1422 ​
1440 1423 </description>
1441 1424 <value type="int">2</value>
1442 1425 </param>
1443 1426 ​
1444 1427 <param type="double" name="smallscalebias" subparam="true">
1445 1428 <shortdescription>Biases the scale selection when using multi-scale or mtmfs deconvolvers </shortdescription>
1446 1429 <description>A numerical control to bias the scales when using multi-scale or mtmfs algorithms.
1447 1430 The peak from each scale's smoothed residual is
1452 1435 A score of 0.0 gives all scales equal weight (default).
1453 1436 A score larger than 0.0 will bias the solution towards smaller scales.
1454 1437 A score smaller than 0.0 will bias the solution towards larger scales.
1455 1438 The effect of smallscalebias is more pronounced when using multi-scale relative to mtmfs.
1456 1439 </description>
1457 1440 <value type="double">0.0</value>
1458 1441 </param>
1459 1442 ​
1460 1443 <param type="double" name="fusedthreshold" subparam="true">
1461 1444 <shortdescription>Threshold for triggering Hogbom Clean </shortdescription>
1462 - <description> Threshold for triggering Hogbom Clean (number in units of Jy)
1445 + <description> Threshold for triggering Hogbom Clean (number in units of Jy).
1463 1446 ​
1464 - fusedthreshold = 0.0001 : 0.1 mJy
1447 + fusedthreshold = 0.0001 : 0.1 mJy.
1465 1448 ​
1466 1449 This is a subparameter of the Asp Clean deconvolver. When peak residual
1467 1450 is lower than the threshold, Asp Clean is "switched to Hogbom Clean" (i.e. only use the 0 scale for cleaning) for
1468 1451 the following number of iterations until it switches back to Asp Clean.
1469 1452 ​
1470 1453 NumberIterationsInHogbom = 50 + 2 * (exp(0.05 * NthHogbom) - 1)
1471 1454 ​
1472 1455 , where NthHogbom is the number of times Hogbom Clean has been triggered.
1473 1456 ​
1474 1457 When the Asp Clean detects it is approaching convergence, it uses only the 0 scale for the following number of iterations for better computational efficiency.
1519 1502 ​
1520 1503 </description>
1521 1504 <value type="bool">True</value>
1522 1505 </param>
1523 1506 ​
1524 1507 ​
1525 1508 <param type="any" name="restoringbeam" subparam="true">
1526 1509 <shortdescription>Restoring beam shape to use. Default is the PSF main lobe</shortdescription>
1527 1510 <description> Restoring beam shape/size to use.
1528 1511 ​
1529 - - restoringbeam='' or ['']
1512 + - restoringbeam='' or [''].
1530 1513 A Gaussian fitted to the PSF main lobe (separately per image plane).
1531 1514 ​
1532 - - restoringbeam='10.0arcsec'
1533 - Use a circular Gaussian of this width for all planes
1515 + - restoringbeam='10.0arcsec'.
1516 + Use a circular Gaussian of this width for all planes.
1534 1517 ​
1535 - - restoringbeam=['8.0arcsec','10.0arcsec','45deg']
1536 - Use this elliptical Gaussian for all planes
1518 + - restoringbeam=['8.0arcsec','10.0arcsec','45deg'].
1519 + Use this elliptical Gaussian for all planes.
1537 1520 ​
1538 - - restoringbeam='common'
1521 + - restoringbeam='common'.
1539 1522 Automatically estimate a common beam shape/size appropriate for
1540 - all planes.
1523 + all planes. This option can be used when the beam shape is different as a function of frequency, and will smooth all planes to a single beam, defined by the largest beam in the cube.
1541 1524 ​
1542 1525 Note : For any restoring beam different from the native resolution
1543 1526 the model image is convolved with the beam and added to
1544 1527 residuals that have been convolved to the same target resolution.
1545 1528 ​
1546 1529 </description>
1547 1530 <type>string</type><type>stringVec</type>
1548 1531 <value type="stringVec"/>
1549 1532 </param>
1550 1533 ​
1551 1534 <param type="bool" name="pbcor" subparam="true">
1552 1535 <shortdescription>Apply PB correction on the output restored image</shortdescription>
1553 -<description> Apply PB correction on the output restored image
1536 +<description> Apply PB correction on the output restored image.
1554 1537 ​
1555 1538 A new image with extension .image.pbcor will be created from
1556 1539 the evaluation of .image / .pb for all pixels above the specified pblimit.
1557 1540
1558 1541 Note : Stand-alone PB-correction can be triggered by re-running
1559 1542 tclean with the appropriate imagename and with
1560 1543 niter=0, calcpsf=False, calcres=False, pbcor=True, vptable='vp.tab'
1561 - ( where vp.tab is the name of the vpmanager file.
1562 - See the inline help for the 'vptable' parameter )
1544 + ( where vp.tab is the name of the vpmanager file;
1545 + see the inline help for the 'vptable' parameter ). Alternatively, task impbcor can be used for primary beam correction using the .image and .pb files.
1563 1546 ​
1564 1547 Note : For deconvolver='mtmfs', pbcor will divide each Taylor term image by the .tt0 average PB.
1565 1548 For all gridders, this calculation is accurate for small fractional bandwidths.
1566 1549 ​
1567 1550 For large fractional bandwidths, please use one of the following options.
1568 1551 ​
1569 1552 (a) For single pointings, run the tclean task with specmode='mfs', deconvolver='mtmfs',
1570 1553 and gridder='standard' with pbcor=True or False.
1571 1554 If a PB-corrected spectral index is required,
1572 1555 please use the widebandpbcor task to apply multi-tern PB-correction.
1593 1576 </description>
1594 1577 <value type="bool">False</value>
1595 1578 </param>
1596 1579 ​
1597 1580 ​
1598 1581 ​
1599 1582 ​
1600 1583 ​
1601 1584 <param type="string" name="outlierfile">
1602 1585 <shortdescription>Name of outlier-field image definitions</shortdescription>
1603 -<description>Name of outlier-field image definitions
1586 +<description>Name of outlier-field image definitions.
1604 1587 ​
1605 1588 A text file containing sets of parameter=value pairs,
1606 1589 one set per outlier field.
1607 1590 ​
1608 1591 Example : outlierfile='outs.txt'
1609 1592 ​
1610 1593 Contents of outs.txt :
1611 1594 ​
1612 1595 imagename=tst1
1613 1596 nchan=1
1623 1606 phasecenter=J2000 19:58:40.895 +40.56.00.000
1624 1607 mask=circle[[60pix,60pix],20pix]
1625 1608 ​
1626 1609 The following parameters are currently allowed to be different between
1627 1610 the main field and the outlier fields (i.e. they will be recognized if found
1628 1611 in the outlier text file). If a parameter is not listed, the value is picked from
1629 1612 what is defined in the main task input.
1630 1613 ​
1631 1614 imagename, imsize, cell, phasecenter, startmodel, mask
1632 1615 specmode, nchan, start, width, nterms, reffreq,
1633 - gridder, deconvolver, wprojplanes
1616 + gridder, deconvolver, wprojplanes.
1634 1617 ​
1635 1618 Note : 'specmode' is an option, so combinations of mfs and cube
1636 1619 for different image fields, for example, are supported.
1637 1620 'deconvolver' and 'gridder' are also options that allow different
1638 1621 imaging or deconvolution algorithm per image field.
1639 1622 ​
1640 1623 For example, multiscale with wprojection and 16 w-term planes
1641 1624 on the main field and mtmfs with nterms=3 and wprojection
1642 1625 with 64 planes on a bright outlier source for which the frequency
1643 1626 dependence of the primary beam produces a strong effect that
1644 1627 must be modeled. The traditional alternative to this approach is
1645 1628 to first image the outlier, subtract it out of the data (uvsub) and
1646 1629 then image the main field.
1647 1630 ​
1648 - Note : If you encounter a use-case where some other parameter needs
1649 - to be allowed in the outlier file (and it is logical to do so), please
1650 - send us feedback. The above is an initial list.
1651 1631 ​
1652 1632 </description>
1653 1633 <value type="string"/>
1654 1634 </param>
1655 1635 ​
1656 1636 ​
1657 1637 ​
1658 1638 ​
1659 1639 ​
1660 1640 ​
1661 1641 <param type="string" name="weighting">
1662 1642 <shortdescription>Weighting scheme (natural,uniform,briggs, superuniform, radial, briggsabs[experimental], briggsbwtaper[experimental])</shortdescription>
1663 -<description>Weighting scheme (natural,uniform,briggs,superuniform,radial, briggsabs, briggsbwtaper)
1643 +<description>Weighting scheme (natural,uniform,briggs,superuniform,radial, briggsabs, briggsbwtaper).
1664 1644 ​
1665 1645 During gridding of the dirty or residual image, each visibility value is
1666 1646 multiplied by a weight before it is accumulated on the uv-grid.
1667 1647 The PSF's uv-grid is generated by gridding only the weights (weightgrid).
1668 1648 ​
1669 1649 weighting='natural' : Gridding weights are identical to the data weights
1670 1650 from the MS. For visibilities with similar data weights,
1671 1651 the weightgrid will follow the sample density
1672 1652 pattern on the uv-plane. This weighting scheme
1673 1653 provides the maximum imaging sensitivity at the
1674 - expense of a possibly fat PSF with high sidelobes.
1654 + expense of a PSF with possibly wider main lobes and high sidelobes.
1675 1655 It is most appropriate for detection experiments
1676 1656 where sensitivity is most important.
1677 1657 ​
1678 1658 weighting='uniform' : Gridding weights per visibility data point are the
1679 1659 original data weights divided by the total weight of
1680 1660 all data points that map to the same uv grid cell :
1681 1661 ' data_weight / total_wt_per_cell '.
1682 1662 ​
1683 1663 The weightgrid is as close to flat as possible resulting
1684 1664 in a PSF with a narrow main lobe and suppressed
1766 1746 ​
1767 1747 <param type="any" name="noise" subparam="true"><shortdescription>noise parameter for briggs abs mode weighting</shortdescription><description>noise parameter for briggs abs mode weighting</description>
1768 1748
1769 1749 <any type="variant"/>
1770 1750 <value type="string">1.0Jy</value>
1771 1751 </param>
1772 1752
1773 1753 <param type="int" name="npixels" subparam="true">
1774 1754 <shortdescription>Number of pixels to determine uv-cell size </shortdescription>
1775 1755 <description>Number of pixels to determine uv-cell size for super-uniform weighting
1776 - (0 defaults to -/+ 3 pixels)
1756 + (0 defaults to -/+ 3 pixels).
1777 1757 ​
1778 1758 npixels -- uv-box used for weight calculation
1779 1759 a box going from -npixel/2 to +npixel/2 on each side
1780 1760 around a point is used to calculate weight density.
1781 1761 ​
1782 1762 npixels=2 goes from -1 to +1 and covers 3 pixels on a side.
1783 1763 ​
1784 1764 npixels=0 implies a single pixel, which does not make sense for
1785 1765 superuniform weighting. Therefore, for 'superuniform'
1786 1766 weighting, if npixels=0 it will be forced to 6 (or a box
1787 1767 of -3pixels to +3pixels) to cover 7 pixels on a side.
1788 1768 ​
1789 1769 </description>
1790 1770 <value type="int">0</value>
1791 1771 </param>
1792 1772 ​
1793 1773 ​
1794 1774 ​
1795 1775 <param type="stringVec" name="uvtaper" subparam="true">
1796 1776 <shortdescription>uv-taper on outer baselines in uv-plane</shortdescription>
1797 -<description>uv-taper on outer baselines in uv-plane
1777 +<description>uv-taper on outer baselines in uv-plane.
1798 1778 ​
1799 1779 Apply a Gaussian taper in addition to the weighting scheme specified
1800 1780 via the 'weighting' parameter. Higher spatial frequencies are weighted
1801 1781 down relative to lower spatial frequencies to suppress artifacts
1802 1782 arising from poorly sampled areas of the uv-plane. It is equivalent to
1803 1783 smoothing the PSF obtained by other weighting schemes and can be
1804 1784 specified either as the HWHM of a Gaussian in uv-space (eg. units of lambda)
1805 1785 or as the FWHM of a Gaussian in the image domain (eg. angular units like arcsec).
1806 1786 ​
1807 - uvtaper = [bmaj, bmin, bpa]
1787 + uvtaper = [bmaj, bmin, bpa].
1808 1788 ​
1809 - Note : FWHM_uv_lambda = (4 log2) / ( pi * FWHM_lm_radians )
1789 + Note : FWHM_uv_lambda = (4 log2) / ( pi * FWHM_lm_radians ).
1810 1790
1811 - A FWHM_lm of 100.000 arcsec maps to a HWHM_uv of 910.18 lambda
1812 - A FWHM_lm of 1 arcsec maps to a HWHM_uv of 91 klambda
1791 + A FWHM_lm of 100.000 arcsec maps to a HWHM_uv of 910.18 lambda.
1792 + A FWHM_lm of 1 arcsec maps to a HWHM_uv of 91 klambda.
1813 1793
1814 - default: uvtaper=[]; no Gaussian taper applied
1815 - example: uvtaper=['5klambda'] circular taper of HWHM=5 kilo-lambda
1816 - uvtaper=['5klambda','3klambda','45.0deg'] uv-domain HWHM
1817 - uvtaper=['50arcsec','30arcsec','30.0deg'] : image domain FWHM
1818 - uvtaper=['10arcsec'] : image domain FWHM
1819 - uvtaper=['300.0'] default units are lambda in aperture plane
1794 + default: uvtaper=[]; no Gaussian taper applied.
1795 + example: uvtaper=['5klambda'] circular taper of HWHM=5 kilo-lambda.
1796 + uvtaper=['5klambda','3klambda','45.0deg'] uv-domain HWHM.
1797 + uvtaper=['50arcsec','30arcsec','30.0deg'] : image domain FWHM.
1798 + uvtaper=['10arcsec'] : image domain FWHM.
1799 + uvtaper=['300.0'] default units are lambda in aperture plane.
1820 1800 ​
1821 1801 </description>
1822 1802 <value type="vector">
1823 1803 <value/>
1824 1804 </value>
1825 1805 </param>
1826 1806 ​
1827 1807 ​
1828 1808 ​
1829 1809 ​
1830 1810 ​
1831 1811 ​
1832 1812 ​
1833 1813 ​
1834 1814 ​
1835 1815 <param type="int" name="niter">
1836 1816 <shortdescription>Maximum number of iterations</shortdescription>
1837 -<description>Maximum number of iterations
1817 +<description>Maximum number of iterations.
1838 1818 ​
1839 1819 A stopping criterion based on total iteration count.
1840 1820 Currently the parameter type is defined as an integer therefore the integer value
1841 1821 larger than 2147483647 will not be set properly as it causes an overflow.
1842 1822 ​
1843 1823 Iterations are typically defined as the selecting one flux component
1844 1824 and partially subtracting it out from the residual image.
1845 1825 ​
1846 - niter=0 : Do only the initial major cycle (make dirty image, psf, pb, etc)
1826 + niter=0 : Do only the initial major cycle (make dirty image, psf, pb, etc).
1847 1827 ​
1848 1828 niter larger than zero : Run major and minor cycles.
1849 1829 ​
1850 - Note : Global stopping criteria vs major-cycle triggers
1830 + Note : Global stopping criteria vs major-cycle triggers.
1851 1831 ​
1852 1832 In addition to global stopping criteria, the following rules are
1853 1833 used to determine when to terminate a set of minor cycle iterations
1854 - and trigger major cycles [derived from Cotton-Schwab Clean, 1984]
1834 + and trigger major cycles [derived from Cotton-Schwab Clean, 1984].
1855 1835 ​
1856 1836 'cycleniter' : controls the maximum number of iterations per image
1857 1837 plane before triggering a major cycle.
1858 1838 'cyclethreshold' : Automatically computed threshold related to the
1859 1839 max sidelobe level of the PSF and peak residual.
1860 1840 Divergence, detected as an increase of 10% in peak residual from the
1861 - minimum so far (during minor cycle iterations)
1841 + minimum so far (during minor cycle iterations).
1862 1842 ​
1863 1843 The first criterion to be satisfied takes precedence.
1864 1844 ​
1865 1845 Note : Iteration counts for cubes or multi-field images :
1866 1846 For images with multiple planes (or image fields) on which the
1867 1847 deconvolver operates in sequence, iterations are counted across
1868 1848 all planes (or image fields). The iteration count is compared with
1869 1849 'niter' only after all channels/planes/fields have completed their
1870 1850 minor cycles and exited either due to 'cycleniter' or 'cyclethreshold'.
1871 1851 Therefore, the actual number of iterations reported in the logger
1872 1852 can sometimes be larger than the user specified value in 'niter'.
1873 1853 For example, with niter=100, cycleniter=20,nchan=10,threshold=0,
1874 1854 a total of 200 iterations will be done in the first set of minor cycles
1875 1855 before the total is compared with niter=100 and it exits.
1876 1856 ​
1877 - Note : Additional global stopping criteria include
1878 - - no change in peak residual across two major cycles
1879 - - a 50% or more increase in peak residual across one major cycle
1857 + Note : Additional global stopping criteria include:
1858 + - no change in peak residual across two major cycles.
1859 + - a 50% or more increase in peak residual across one major cycle.
1880 1860 ​
1881 1861 ​
1882 1862 </description>
1883 1863 <value type="int">0</value>
1884 1864 </param>
1885 1865 ​
1886 1866 <param type="double" name="gain" subparam="true">
1887 1867 <shortdescription>Loop gain</shortdescription>
1888 -<description>Loop gain
1868 +<description>Loop gain.
1889 1869 ​
1890 1870 Fraction of the source flux to subtract out of the residual image
1891 1871 for the CLEAN algorithm and its variants.
1892 1872 ​
1893 1873 A low value (0.2 or less) is recommended when the sky brightness
1894 1874 distribution is not well represented by the basis functions used by
1895 1875 the chosen deconvolution algorithm. A higher value can be tried when
1896 1876 there is a good match between the true sky brightness structure and
1897 1877 the basis function shapes. For example, for extended emission,
1898 1878 multiscale clean with an appropriate set of scale sizes will tolerate
1899 - a higher loop gain than Clark clean (for example).
1879 + a higher loop gain than Clark clean.
1900 1880 ​
1901 1881
1902 1882 ​
1903 1883 </description>
1904 1884 <value type="double">0.1</value>
1905 1885 </param>
1906 1886 ​
1907 1887 <param type="any" name="threshold" subparam="true">
1908 1888 <shortdescription>Stopping threshold </shortdescription>
1909 -<description>Stopping threshold (number in units of Jy, or string)
1889 +<description>Stopping threshold (number in units of Jy, or string).
1910 1890 ​
1911 1891 A global stopping threshold that the peak residual (within clean mask)
1912 1892 across all image planes is compared to.
1913 1893 ​
1914 1894 threshold = 0.005 : 5mJy
1915 1895 threshold = '5.0mJy'
1916 1896 ​
1917 1897 Note : A 'cyclethreshold' is internally computed and used as a major cycle
1918 - trigger. It is related what fraction of the PSF can be reliably
1898 + trigger. It is related to what fraction of the PSF can be reliably
1919 1899 used during minor cycle updates of the residual image. By default
1920 1900 the minor cycle iterations terminate once the peak residual reaches
1921 1901 the first sidelobe level of the brightest source.
1922 1902 ​
1923 1903 'cyclethreshold' is computed as follows using the settings in
1924 1904 parameters 'cyclefactor','minpsffraction','maxpsffraction','threshold' :
1925 1905 ​
1926 1906 psf_fraction = max_psf_sidelobe_level \* 'cyclefactor'
1927 1907 psf_fraction = max(psf_fraction, 'minpsffraction');
1928 1908 psf_fraction = min(psf_fraction, 'maxpsffraction');
1929 1909 cyclethreshold = peak_residual \* psf_fraction
1930 1910 cyclethreshold = max( cyclethreshold, 'threshold' )
1931 1911 ​
1932 1912 If nsigma is set (&gt;0.0), the N-sigma threshold is calculated (see
1933 1913 the description under nsigma), then cyclethreshold is further modified as,
1934 1914 ​
1935 - cyclethreshold = max( cyclethreshold, nsgima_threshold )
1915 + cyclethreshold = max( cyclethreshold, nsgima_threshold ).
1936 1916 ​
1937 1917 ​
1938 1918 'cyclethreshold' is made visible and editable only in the
1939 1919 interactive GUI when tclean is run with interactive=True.
1940 1920 </description>
1941 1921 ​
1942 1922 <value type="double">0.0</value>
1943 1923 </param>
1944 1924 ​
1945 1925 <param type="double" name="nsigma" subparam="true">
1946 1926 <shortdescription>Multiplicative factor for rms-based threshold stopping</shortdescription>
1947 -<description>Multiplicative factor for rms-based threshold stopping
1927 +<description>Multiplicative factor for rms-based threshold stopping.
1948 1928 ​
1949 1929 N-sigma threshold is calculated as nsigma \* rms value per image plane determined
1950 1930 from a robust statistics. For nsigma &gt; 0.0, in a minor cycle, a maximum of the two values,
1951 1931 the N-sigma threshold and cyclethreshold, is used to trigger a major cycle
1952 1932 (see also the descreption under 'threshold').
1953 1933 Set nsigma=0.0 to preserve the previous tclean behavior without this feature.
1954 1934 The top level parameter, fastnoise is relevant for the rms noise calculation which is used
1955 1935 to determine the threshold.
1956 1936 ​
1957 1937 The parameter 'nsigma' may be an int, float, or a double.
1958 1938 ​
1959 1939 </description>
1960 1940 <value type="double">0.0</value>
1961 1941 </param>
1962 1942 ​
1963 1943 <param type="int" name="cycleniter" subparam="true">
1964 1944 <shortdescription>Maximum number of minor-cycle iterations</shortdescription>
1965 1945 <description>Maximum number of minor-cycle iterations (per plane) before triggering
1966 - a major cycle
1946 + a major cycle.
1967 1947 ​
1968 1948 For example, for a single plane image, if niter=100 and cycleniter=20,
1969 1949 there will be 5 major cycles after the initial one (assuming there is no
1970 1950 threshold based stopping criterion). At each major cycle boundary, if
1971 1951 the number of iterations left over (to reach niter) is less than cycleniter,
1972 1952 it is set to the difference.
1973 1953 ​
1974 1954 Note : cycleniter applies per image plane, even if cycleniter x nplanes
1975 1955 gives a total number of iterations greater than 'niter'. This is to
1976 1956 preserve consistency across image planes within one set of minor
1977 1957 cycle iterations.
1978 1958 ​
1979 1959 </description>
1980 1960 <value type="int">-1</value>
1981 1961 </param>
1982 1962 ​
1983 1963 <param type="double" name="cyclefactor" subparam="true">
1984 1964 <shortdescription>Scaling on PSF sidelobe level to compute the minor-cycle stopping threshold.</shortdescription>
1985 1965 <description>Scaling on PSF sidelobe level to compute the minor-cycle stopping threshold.
1986 1966 ​
1987 1967 Please refer to the Note under the documentation for 'threshold' that
1988 - discussed the calculation of 'cyclethreshold'
1968 + discussed the calculation of 'cyclethreshold'.
1989 1969 ​
1990 1970 cyclefactor=1.0 results in a cyclethreshold at the first sidelobe level of
1991 1971 the brightest source in the residual image before the minor cycle starts.
1992 1972 ​
1993 1973 cyclefactor=0.5 allows the minor cycle to go deeper.
1994 1974 cyclefactor=2.0 triggers a major cycle sooner.
1995 1975 ​
1996 1976 </description>
1997 1977 <value type="double">1.0</value>
1998 1978 </param>
1999 1979 ​
2000 1980 <param type="double" name="minpsffraction" subparam="true">
2001 1981 <shortdescription>PSF fraction that marks the max depth of cleaning in the minor cycle</shortdescription>
2002 -<description>PSF fraction that marks the max depth of cleaning in the minor cycle
1982 +<description>PSF fraction that marks the max depth of cleaning in the minor cycle.
2003 1983 ​
2004 1984 Please refer to the Note under the documentation for 'threshold' that
2005 - discussed the calculation of 'cyclethreshold'
1985 + discussed the calculation of 'cyclethreshold'.
2006 1986 ​
2007 1987 For example, minpsffraction=0.5 will stop cleaning at half the height of
2008 1988 the peak residual and trigger a major cycle earlier.
2009 1989 ​
2010 1990 </description>
2011 1991 <value type="double">0.05</value>
2012 1992 </param>
2013 1993 ​
2014 1994 <param type="double" name="maxpsffraction" subparam="true">
2015 1995 <shortdescription>PSF fraction that marks the minimum depth of cleaning in the minor cycle </shortdescription>
2016 -<description>PSF fraction that marks the minimum depth of cleaning in the minor cycle
1996 +<description>PSF fraction that marks the minimum depth of cleaning in the minor cycle.
2017 1997 ​
2018 1998 Please refer to the Note under the documentation for 'threshold' that
2019 - discussed the calculation of 'cyclethreshold'
1999 + discussed the calculation of 'cyclethreshold'.
2020 2000 ​
2021 2001 For example, maxpsffraction=0.8 will ensure that at least the top 20
2022 2002 percent of the source will be subtracted out in the minor cycle even if
2023 2003 the first PSF sidelobe is at the 0.9 level (an extreme example), or if the
2024 2004 cyclefactor is set too high for anything to get cleaned.
2025 2005 ​
2026 2006 </description>
2027 2007 <value type="double">0.8</value>
2028 2008 </param>
2029 2009 ​
2030 2010 ​
2031 2011 <param type="bool" name="interactive" subparam="true">
2032 2012 <shortdescription>Modify masks and parameters at runtime</shortdescription>
2033 -<description>Modify masks and parameters at runtime
2013 +<description>Modify masks and parameters at runtime.
2034 2014 ​
2035 2015 interactive=True will trigger an interactive GUI at every major cycle
2036 2016 boundary (after the major cycle and before the minor cycle).
2037 2017 ​
2038 2018 Options for runtime parameter modification are :
2039 2019 ​
2040 2020 Interactive clean mask : Draw a 1/0 mask (appears as a contour) by hand.
2041 2021 If a mask is supplied at the task interface or if
2042 2022 automasking is invoked, the current mask is
2043 2023 displayed in the GUI and is available for manual
2044 2024 editing.
2045 2025 ​
2046 2026 Note : If a mask contour is not visible, please
2047 2027 check the cursor display at the bottom of
2048 2028 GUI to see which parts of the mask image
2049 2029 have ones and zeros. If the entire mask=1
2050 2030 no contours will be visible.
2051 2031 ​
2052 2032 ​
2053 - Operation buttons : -- Stop execution now (restore current model and exit)
2033 + Operation buttons : -- Stop execution now (restore current model and exit).
2054 2034 -- Continue on until global stopping criteria are reached
2055 - without stopping for any more interaction
2035 + without stopping for any more interaction.
2056 2036 -- Continue with minor cycles and return for interaction
2057 2037 after the next major cycle.
2058 2038 ​
2059 - Iteration control : -- max cycleniter : Trigger for the next major cycle
2039 + Iteration control : -- max cycleniter : Trigger for the next major cycle.
2060 2040 ​
2061 2041 The display begins with
2062 2042 [ min( cycleniter, niter - itercount ) ]
2063 2043 and can be edited by hand.
2064 2044 ​
2065 2045 -- iterations left : The display begins with [niter-itercount ]
2066 2046 and can be edited to increase or
2067 2047 decrease the total allowed niter.
2068 2048 ​
2069 - -- threshold : Edit global stopping threshold
2049 + -- threshold : Edit global stopping threshold.
2070 2050 ​
2071 2051 -- cyclethreshold : The display begins with the
2072 2052 automatically computed value
2073 2053 (see Note in help for 'threshold'),
2074 2054 and can be edited by hand.
2075 2055 ​
2076 2056 All edits will be reflected in the log messages that appear
2077 2057 once minor cycles begin.
2078 2058 ​
2079 2059 </description>
2113 2093 of the residual, and no minor cycles are executed.
2114 2094 Case 2; nmajor=1, calcres=False: The major cycle is done as part of the
2115 2095 major/minor cycle loop, and 1 minor cycle will be executed.
2116 2096 </description>
2117 2097 <value type="int">-1</value>
2118 2098 </param>
2119 2099 ​
2120 2100 ​
2121 2101 <param type="bool" name="fullsummary">
2122 2102 <shortdescription>Return dictionary with complete convergence history</shortdescription>
2123 - <description>Return dictionary with complete convergence history
2103 + <description>Return dictionary with complete convergence history.
2124 2104 ​
2125 2105 fullsummary=True: A full version of the summary dictionary is returned.
2126 2106 Keys include 'iterDone','peakRes','modelFlux','cycleThresh' that record the
2127 2107 convergence state at the end of each set of minor cycle iterations
2128 2108 separately for each image plane (i.e. channel/stokes) being
2129 2109 deconvolved. Additional keys report the convergence state at the
2130 2110 start of minor cycle iterations, stopping criteria that triggered major
2131 2111 cycles, and a processor ID per channel, for parallel cube runs.
2132 2112 ​
2133 2113 fullsummary=False (default): A shorten version of the summary dictionary is returned
2146 2126 </description>
2147 2127 <value type='bool'>False</value>
2148 2128 </param>
2149 2129 ​
2150 2130 ​
2151 2131
2152 2132 ​
2153 2133 <param type="string" name="usemask">
2154 2134 <shortdescription>Type of mask(s) for deconvolution: user, pb, or auto-multithresh</shortdescription>
2155 2135 ​
2156 -<description>Type of mask(s) to be used for deconvolution
2136 +<description>Type of mask(s) to be used for deconvolution.
2157 2137 ​
2158 - user: (default) mask image(s) or user specified region file(s) or string CRTF expression(s)
2159 - subparameters: mask, pbmask
2160 - pb: primary beam mask
2161 - subparameter: pbmask
2138 + user: (default) mask image(s) or user specified region file(s) or string CRTF expression(s).
2139 + subparameters: mask, pbmask.
2140 + pb: primary beam mask.
2141 + subparameter: pbmask.
2162 2142 ​
2163 - Example: usemask=&quot;pb&quot;, pbmask=0.2
2143 + Example: usemask=&quot;pb&quot;, pbmask=0.2.
2164 2144 Construct a mask at the 0.2 pb gain level.
2165 2145 (Currently, this option will work only with
2166 2146 gridders that produce .pb (i.e. mosaic and awproject)
2167 - or if an externally produced .pb image exists on disk)
2147 + or if an externally produced .pb image exists on disk).
2168 2148 ​
2169 - auto-multithresh : auto-masking by multiple thresholds for deconvolution
2149 + auto-multithresh : auto-masking by multiple thresholds for deconvolution.
2170 2150 subparameters : sidelobethreshold, noisethreshold, lownoisethreshold, negativethrehsold, smoothfactor,
2171 - minbeamfrac, cutthreshold, pbmask, growiterations, dogrowprune, minpercentchange, verbose
2172 - Additional top level parameter relevant to auto-multithresh: fastnoise
2151 + minbeamfrac, cutthreshold, pbmask, growiterations, dogrowprune, minpercentchange, verbose.
2152 + Additional top level parameter relevant to auto-multithresh: fastnoise.
2173 2153 ​
2174 2154 if pbmask is &gt;0.0, the region outside the specified pb gain level is excluded from
2175 2155 image statistics in determination of the threshold.
2176 2156 ​
2177 2157
2178 2158
2179 2159 ​
2180 2160 Note: By default the intermediate mask generated by automask at each deconvolution cycle
2181 2161 is over-written in the next cycle but one can save them by setting
2182 2162 the environment variable, SAVE_ALL_AUTOMASKS=&quot;true&quot;.
2189 2169 <allowed kind="enum">
2190 2170 <value>user</value>
2191 2171 <value>pb</value>
2192 2172 <value>auto-multithresh</value>
2193 2173 </allowed>
2194 2174 </param>
2195 2175 ​
2196 2176
2197 2177 <param type="any" name="mask" subparam="true">
2198 2178 <shortdescription>Mask (a list of image name(s) or region file(s) or region string(s) )</shortdescription>
2199 -<description>Mask (a list of image name(s) or region file(s) or region string(s)
2179 +<description>Mask (a list of image name(s) or region file(s) or region string(s).
2200 2180 ​
2201 2181
2202 2182 The name of a CASA image or region file or region string that specifies
2203 2183 a 1/0 mask to be used for deconvolution. Only locations with value 1 will
2204 2184 be considered for the centers of flux components in the minor cycle.
2205 2185 If regions specified fall completely outside of the image, tclean will throw an error.
2206 2186 ​
2207 2187 Manual mask options/examples :
2208 2188 ​
2209 2189 mask='xxx.mask' : Use this CASA image named xxx.mask and containing
2223 2203 parameter. ]
2224 2204 ​
2225 2205 ​
2226 2206 mask='xxx.crtf' : A text file with region strings and the following on the first line
2227 2207 ( #CRTFv0 CASA Region Text Format version 0 )
2228 2208 This is the format of a file created via the viewer's region
2229 2209 tool when saved in CASA region file format.
2230 2210 ​
2231 2211 mask='circle[[40pix,40pix],10pix]' : A CASA region string.
2232 2212 ​
2233 - mask=['xxx.mask','xxx.crtf', 'circle[[40pix,40pix],10pix]'] : a list of masks
2213 + mask=['xxx.mask','xxx.crtf', 'circle[[40pix,40pix],10pix]'] : a list of masks.
2234 2214 ​
2235 2215 ​
2236 2216
2237 2217 ​
2238 2218 ​
2239 2219 Note : Mask images for deconvolution must contain 1 or 0 in each pixel.
2240 2220 Such a mask is different from an internal T/F mask that can be
2241 2221 held within each CASA image. These two types of masks are not
2242 2222 automatically interchangeable, so please use the makemask task
2243 2223 to copy between them if you need to construct a 1/0 based mask
2249 2229 </description>
2250 2230 ​
2251 2231 ​
2252 2232 <type>string</type><type>stringVec</type>
2253 2233 <value type="string"/>
2254 2234 </param>
2255 2235 ​
2256 2236 ​
2257 2237 <param type="double" name="pbmask" subparam="true">
2258 2238 <shortdescription>primary beam mask</shortdescription>
2259 -<description>Sub-parameter for usemask: primary beam mask
2239 +<description>Sub-parameter for usemask: primary beam mask.
2260 2240 ​
2261 - Examples : pbmask=0.0 (default, no pb mask)
2262 - pbmask=0.2 (construct a mask at the 0.2 pb gain level)
2241 + Examples : pbmask=0.0 (default, no pb mask).
2242 + pbmask=0.2 (construct a mask at the 0.2 pb gain level).
2263 2243 ​
2264 2244 </description>
2265 2245 <value type="double">0.0</value>
2266 2246 </param>
2267 2247
2268 2248
2269 2249
2270 2250
2271 2251 <param type="double" name="sidelobethreshold" subparam="true">
2272 2252 <shortdescription>sidelobethreshold \* the max sidelobe level \* peak residual</shortdescription>
2273 2253 <value type="double">3.0</value>
2274 -<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold based on sidelobe levels: sidelobethreshold \* max_sidelobe_level \* peak residual
2254 +<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold based on sidelobe levels: sidelobethreshold \* max_sidelobe_level \* peak residual.
2275 2255 ​
2276 2256 </description>
2277 2257 </param>
2278 2258 <param type="double" name="noisethreshold" subparam="true">
2279 2259 <shortdescription>noisethreshold \* rms in residual image + location(median) </shortdescription>
2280 2260 <value type="double">5.0</value>
2281 -<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold based on the noise level: noisethreshold \* rms + location (=median)
2261 +<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold based on the noise level: noisethreshold \* rms + location (=median).
2282 2262 ​
2283 - The rms is calculated from MAD with rms = 1.4826\*MAD.
2263 + The rms is calculated from the median absolute deviation (MAD), with rms = 1.4826\*MAD.
2284 2264 </description>
2285 2265 </param>
2286 2266 <param type="double" name="lownoisethreshold" subparam="true">
2287 2267 <shortdescription>lownoisethreshold \* rms in residual image + location(median) </shortdescription>
2288 2268 <value type="double">1.5</value>
2289 -<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold to grow previously masked regions via binary dilation: lownoisethreshold \* rms in residual image + location (=median)
2269 +<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold to grow previously masked regions via binary dilation: lownoisethreshold \* rms in residual image + location (=median).
2290 2270 ​
2291 - The rms is calculated from MAD with rms = 1.4826\*MAD.
2271 + The rms is calculated from the median absolute deviation (MAD), with rms = 1.4826\*MAD.
2292 2272 </description>
2293 2273 </param>
2294 2274 <param type="double" name="negativethreshold" subparam="true">
2295 2275 <shortdescription>negativethreshold \* rms in residual image + location(median) </shortdescription>
2296 2276 <value type="double">0.0</value>
2297 -<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold for negative features: -1.0* negativethreshold \* rms + location(=median)
2277 +<description>Sub-parameter for &quot;auto-multithresh&quot;: mask threshold for negative features: -1.0* negativethreshold \* rms + location(=median).
2298 2278 ​
2299 - The rms is calculated from MAD with rms = 1.4826\*MAD.
2279 + The rms is calculated from the median absolute deviation (MAD), with rms = 1.4826\*MAD.
2300 2280 </description>
2301 2281 </param>
2302 2282 <param type="double" name="smoothfactor" subparam="true">
2303 2283 <shortdescription>smoothing factor in a unit of the beam</shortdescription>
2304 2284 <value type="double">1.0</value>
2305 -<description>Sub-parameter for &quot;auto-multithresh&quot;: smoothing factor in a unit of the beam
2285 +<description>Sub-parameter for &quot;auto-multithresh&quot;: smoothing factor in a unit of the beam.
2306 2286 </description>
2307 2287 </param>
2308 2288 <param type="double" name="minbeamfrac" subparam="true">
2309 2289 <shortdescription>minimum beam fraction for pruning</shortdescription>
2310 2290 <value type="double">0.3</value>
2311 2291 <description>Sub-parameter for &quot;auto-multithresh&quot;: minimum beam fraction in size to prune masks smaller than mimbeamfrac \* beam
2312 2292 &lt;=0.0 : No pruning
2313 2293 </description>
2314 2294 </param>
2315 2295 <param type="double" name="cutthreshold" subparam="true">
2316 2296 <shortdescription>threshold to cut the smoothed mask to create a final mask</shortdescription>
2317 2297 <value type="double">0.01</value>
2318 -<description>Sub-parameter for &quot;auto-multithresh&quot;: threshold to cut the smoothed mask to create a final mask: cutthreshold \* peak of the smoothed mask
2298 +<description>Sub-parameter for &quot;auto-multithresh&quot;: threshold to cut the smoothed mask to create a final mask: cutthreshold \* peak of the smoothed mask.
2319 2299 </description>
2320 2300 </param>
2321 2301 <param type="int" name="growiterations" subparam="true">
2322 2302 <shortdescription>number of binary dilation iterations for growing the mask</shortdescription>
2323 2303 <value type="int">75</value>
2324 -<description>Sub-parameter for &quot;auto-multithresh&quot;: Maximum number of iterations to perform using binary dilation for growing the mask
2304 +<description>Sub-parameter for &quot;auto-multithresh&quot;: Maximum number of iterations to perform using binary dilation for growing the mask.
2325 2305 </description>
2326 2306 </param>
2327 2307 ​
2328 2308 <param type="bool" name="dogrowprune" subparam="true">
2329 2309 <shortdescription>Do pruning on the grow mask</shortdescription>
2330 2310 <value type="bool">True</value>
2331 -<description>Experimental sub-parameter for &quot;auto-multithresh&quot;: Do pruning on the grow mask
2311 +<description>Experimental sub-parameter for &quot;auto-multithresh&quot;: Do pruning on the grow mask.
2332 2312 </description>
2333 2313 </param>
2334 2314 ​
2335 2315 <param type="double" name="minpercentchange" subparam="true">
2336 2316 <shortdescription>minimum percentage change in mask size (per channel plane) to trigger updating of mask by automask </shortdescription>
2337 2317 <value type="double">-1.0</value>
2338 2318 <description>If the change in the mask size in a particular channel is less than minpercentchange, stop masking that channel in subsequent cycles. This check is only applied when noise based threshold is used and when the previous clean major cycle had a cyclethreshold value equal to the clean threshold. Values equal to -1.0 (or any value less than 0.0) will turn off this check (the default). Automask will still stop masking if the current channel mask is an empty mask and the noise threshold was used to determine the mask.
2339 2319 </description>
2340 2320 </param>
2341 2321 ​
2342 2322 <param type="bool" name="verbose" subparam="true">
2343 2323 <shortdescription>True: print more automasking information in the logger</shortdescription>
2344 2324 <value type="bool">False</value>
2345 2325 <description> If it is set to True, the summary of automasking at the end of each automasking process
2346 2326 is printed in the logger. Following information per channel will be listed in the summary.
2347 2327 ​
2348 - chan: channel number
2349 - masking?: F - stop updating automask for the subsequent iteration cycles
2350 - RMS: robust rms noise
2351 - peak: peak in residual image
2352 - thresh_type: type of threshold used (noise or sidelobe)
2353 - thresh_value: the value of threshold used
2354 - N_reg: number of the automask regions
2355 - N_pruned: number of the automask regions removed by pruning
2356 - N_grow: number of the grow mask regions
2357 - N_grow_pruned: number of the grow mask regions removed by pruning
2358 - N_neg_pix: number of pixels for negative mask regions
2359 -​
2328 + chan: channel number.
2329 + masking?: F - stop updating automask for the subsequent iteration cycles.
2330 + RMS: robust rms noise.
2331 + peak: peak in residual image.
2332 + thresh_type: type of threshold used (noise or sidelobe).
2333 + thresh_value: the value of threshold used.
2334 + N_reg: number of the automask regions.
2335 + N_pruned: number of the automask regions removed by pruning.
2336 + N_grow: number of the grow mask regions.
2337 + N_grow_pruned: number of the grow mask regions removed by pruning.
2338 + N_neg_pix: number of pixels for negative mask regions.
2339 +
2360 2340 Note that for a large cube, extra logging may slow down the process.
2361 2341 </description>
2362 2342 </param>
2363 2343 <param type="bool" name="fastnoise">
2364 2344 <shortdescription>True: use the faster (old) noise calculation. False: use the new improved noise calculations</shortdescription>
2365 2345 <value type="bool">True</value>
2366 2346 <description> Only relevant when automask (user='multi-autothresh') and/or n-sigma stopping threshold (nsigma&gt;0.0) are/is used. If it is set to True, a simpler but faster noise calucation is used.
2367 2347 In this case, the threshold values are determined based on classic statistics (using all
2368 2348 unmasked pixels for the calculations).
2369 2349
2370 2350 If it is set to False, the new noise calculation
2371 2351 method is used based on pre-existing mask.
2372 2352
2373 - Case 1: no exiting mask
2374 - Calculate image statistics using Chauvenet algorithm
2353 + Case 1: no exiting mask.
2354 + Calculate image statistics using Chauvenet algorithm.
2375 2355
2376 - Case 2: there is an existing mask
2356 + Case 2: there is an existing mask.
2377 2357 Calculate image statistics by classical method on the region
2378 2358 outside the mask and inside the primary beam mask.
2379 2359 ​
2380 - In all cases above RMS noise is calculated from MAD.
2360 + In all cases above RMS noise is calculated from the median absolute deviation (MAD).
2381 2361 </description>
2382 2362 </param>
2383 2363 ​
2384 2364 ​
2385 2365 ​
2386 2366 ​
2387 2367 <param type="bool" name="restart">
2388 2368 <shortdescription>True : Re-use existing images. False : Increment imagename</shortdescription>
2389 2369 <description> Restart using existing images (and start from an existing model image)
2390 2370 or automatically increment the image name and make a new image set.
2391 2371 ​
2392 2372 True : Re-use existing images. If imagename.model exists the subsequent
2393 2373 run will start from this model (i.e. predicting it using current gridder
2394 2374 settings and starting from the residual image). Care must be taken
2395 2375 when combining this option with startmodel. Currently, only one or
2396 2376 the other can be used.
2397 2377 ​
2398 2378 startmodel='', imagename.model exists :
2399 - - Start from imagename.model
2379 + - Start from imagename.model.
2400 2380 startmodel='xxx', imagename.model does not exist :
2401 - - Start from startmodel
2381 + - Start from startmodel.
2402 2382 startmodel='xxx', imagename.model exists :
2403 2383 - Exit with an error message requesting the user to pick
2404 2384 only one model. This situation can arise when doing one
2405 2385 run with startmodel='xxx' to produce an output
2406 2386 imagename.model that includes the content of startmodel,
2407 2387 and wanting to restart a second run to continue deconvolution.
2408 2388 Startmodel should be set to '' before continuing.
2409 2389 ​
2410 2390 If any change in the shape or coordinate system of the image is
2411 2391 desired during the restart, please change the image name and
2435 2415 'outry' and 'outtry_2' have not been used.
2436 2416 ​
2437 2417 ​
2438 2418 </description>
2439 2419 <value type="bool">True</value>
2440 2420 </param>
2441 2421 ​
2442 2422 ​
2443 2423 <param type="string" name="savemodel">
2444 2424 <shortdescription>Options to save model visibilities (none, virtual, modelcolumn)</shortdescription>
2445 -<description>Options to save model visibilities (none, virtual, modelcolumn)
2425 +<description>Options to save model visibilities (none, virtual, modelcolumn).
2446 2426 ​
2447 2427 Often, model visibilities must be created and saved in the MS
2448 2428 to be later used for self-calibration (or to just plot and view them).
2449 2429 ​
2450 2430 none : Do not save any model visibilities in the MS. The MS is opened
2451 2431 in readonly mode.
2452 2432 ​
2453 2433 Model visibilities can be predicted in a separate step by
2454 2434 restarting tclean with niter=0,savemodel=virtual or modelcolumn
2455 2435 and not changing any image names so that it finds the .model on
2495 2475 <value>virtual</value>
2496 2476 <value>modelcolumn</value>
2497 2477 </allowed>
2498 2478 </param>
2499 2479 ​
2500 2480 ​
2501 2481 ​
2502 2482 ​
2503 2483 <param type="bool" name="calcres">
2504 2484 <shortdescription>Calculate initial residual image</shortdescription>
2505 -<description>Calculate initial residual image
2485 +<description>Calculate initial residual image.
2506 2486 ​
2507 2487 This parameter controls what the first major cycle does.
2508 2488 ​
2509 2489 calcres=False with niter greater than 0 will assume that
2510 2490 a .residual image already exists and that the minor cycle can
2511 2491 begin without recomputing it.
2512 2492 ​
2513 2493 calcres=False with niter=0 implies that only the PSF will be made
2514 2494 and no data will be gridded.
2515 2495 ​
2566 2546 </description>
2567 2547 <value type="double">0.35</value>
2568 2548 ​
2569 2549 </param>
2570 2550
2571 2551
2572 2552
2573 2553 ​
2574 2554 <param type="bool" name="parallel">
2575 2555 <shortdescription>Run major cycles in parallel</shortdescription>
2576 - <description>Run major cycles in parallel (this feature is experimental)
2556 + <description>Run major cycles in parallel.
2577 2557 ​
2578 2558 Parallel tclean will run only if casa has already been started using mpirun.
2579 - Please refer to HPC documentation for details on how to start this on your system.
2559 + Please refer to external resources on high performance computing for details on how to start this on your system.
2580 2560 ​
2581 2561 Example : mpirun -n 3 -xterm 0 `which casa`
2582 2562 ​
2583 2563 Continuum Imaging :
2584 - - Data are partitioned (in time) into NProc pieces
2585 - - Gridding/iFT is done separately per partition
2586 - - Images (and weights) are gathered and then normalized
2587 - - One non-parallel minor cycle is run
2588 - - Model image is scattered to all processes
2589 - - Major cycle is done in parallel per partition
2564 + - Data are partitioned (in time) into NProc pieces.
2565 + - Gridding/iFT is done separately per partition.
2566 + - Images (and weights) are gathered and then normalized.
2567 + - One non-parallel minor cycle is run.
2568 + - Model image is scattered to all processes.
2569 + - Major cycle is done in parallel per partition.
2590 2570 ​
2591 2571 Cube Imaging :
2592 - - Data and Image coordinates are partitioned (in freq) into NProc pieces
2593 - - Each partition is processed independently (major and minor cycles)
2594 - - All processes are synchronized at major cycle boundaries for convergence checks
2595 - - At the end, cubes from all partitions are concatenated along the spectral axis
2572 + - Data and Image coordinates are partitioned (in freq) into NProc pieces.
2573 + - Each partition is processed independently (major and minor cycles).
2574 + - All processes are synchronized at major cycle boundaries for convergence checks.
2575 + - At the end, cubes from all partitions are concatenated along the spectral axis.
2596 2576 ​
2597 2577 Note 1 : Iteration control for cube imaging is independent per partition.
2598 2578 - There is currently no communication between them to synchronize
2599 2579 information such as peak residual and cyclethreshold. Therefore,
2600 2580 different chunks may trigger major cycles at different levels.
2601 2581 (Proper synchronization of iteration control is work in progress.)
2602 2582 ​
2603 2583 </description>
2604 2584 <value type="bool">False</value>
2605 2585 </param>
2884 2864 ​
2885 2865 ​
2886 2866 </constraints>
2887 2867 ​
2888 2868 </input>
2889 2869 ​
2890 2870 <returns type="void"/>
2891 2871 ​
2892 2872 <example>
2893 2873 ​
2894 - Please refer to the CASAdocs pages for the task tclean for examples.
2874 +For more information, see the task pages of tclean in CASA Docs:
2875 +​
2876 +https://casadocs.readthedocs.io
2877 +​
2895 2878 ​
2896 2879 </example>
2897 2880 ​
2898 2881 </task>
2899 2882 ​
2900 2883 </casaxml>

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