; SCIMG ;--------------------------------------------------------------- ;! Full-featured imaging plus self-calibration loop with editing ;# TASK AP IMAGING CALIBRATION EDITING OOP INTERACTIVE ;----------------------------------------------------------------------- ;; Copyright (C) 1995-2000, 2002-2004, 2006-2007, 2009-2010 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- SCIMG LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC SCIMG: Full-featured imaging plus self-calibration INNAME Input UV data (name) INCLASS Input UV data (class) INSEQ Input UV data (seq. #) INDISK Input UV data disk drive # OUTNAME Output image name OUTSEQ -1.0 9999.0 Output image seq. no. OUTDISK Output image disk drive # OUT2NAME Output UV file name OUT2CLAS Output UV file class OUT2SEQ -1.0 9999.0 Output UV file seq. # OUT2DISK 0.0 9.0 Output UV file disk drive # Imaging info CELLSIZE 1.E-12 (X,Y) size of grid in asec IMSIZE 0.0 4096. Image size (power of 2) NFIELD 0. 4096. Number of fields (max 4096) DO3DIMAG -1.0 1. > 0 => use different tangent points for each field FLDSIZE -1.0 8192. Clean size of each field. RASHIFT RA shift per field (asec) DECSHIFT DEC shift per field (asec) UVTAPER 0. (U,V) Gaussian taper units are kilo-lambda UVRANGE 0. Min & max baseline (klambda) UVWTFN UV dist. weight function blank => uniform UVSIZE 0. Array size for doing uniform weights. 0 -> actual field size. ?? ROBUST Robustness power: -4 -> pure uniform weights, 4 => natural UVBOX 0. 128. Additional rows and columns used in weighting. UVBXFN Box function type when UVBOX > 0. 0 -> 1 round pill box. ROTATE Rotate image CCW from N by ROTATE degrees ZEROSP 0-spacing fluxes and weights XTYPE 0. 10. Conv. function type in x default spheroidal YTYPE 0. 10. Conv. function type in y default spheroidal XPARM Conv. function parms for x YPARM Conv. function parms for y Cleaning info GUARD -1.0 0.9 x,y guard band fractional radius NBOXES 0.0 50.0 Number of boxes for CLEAN CLBOX -2.0 4096.0 Four coordinates for each box BOXFILE Input file of field params and Clean boxes; ' ' => use FLDSIZE, RASHIFT, DECSHIFT, NBOXES, CLBOX only. OBOXFILE * Output file for final Clean boxes GAIN * 0.0 2.0 CLEAN loop gain FLUX * Minimum CLEAN component (Jy) MINPATCH * 0.0 Min. BEAM half-width in AP. NITER * 0.0 Maximum # of CLEAN components BMAJ * -999.9 FWHM(asec) major axis CLEAN * restoring beam. BMIN * -999.9 FWHM(asec) minor axis CLEAN * restoring beam. BPA * -360.0 360.0 CLEAN beam position angle OVERLAP -1.0 2.0 1 => restore components to overlapped fields, 2=> expect overlaps while Cleaning ONEBEAM -1.0 1.0 > 0 use only 1 dirty beam per resolution in multi-facet Cleans FACTOR * -5.0 5.0 Speedup factor see HELP MAXPIXEL * 0.0 500000.0 Maximum pixels searched in * each major cycle. CMETHOD Modeling method: 'DFT','GRID',' ' Self cal info NMAPS * Number of self-cal loops. SMODEL Initial model, 1=flux,2=x,3=y REFANT * Reference antenna SOLINT * Solution interval (min) APARM Control parameters 1=min. no. antennas 2 >0 => normalize gain 3 > 0 => avg. RR,LL 5 > 0 => avg. IFs. 6=print level, 1=some 7=soln SNR cutoff (0=>5) 8=SIGMA (see HELP SCIMG) 9=Edit averaging time 10=Amplitude smoothing time SOLTYPE * Soln type,' ','L1','GCON', * 'R', 'L1R', 'GCOR' SOLMODE * Soln. mode: 'A&P','P','P!A', * 'GCON' SOLCON * Gain constraint factor. ANTWT * Ant. weights (0=>1.0) GAINERR * Std. Dev. of antenna gains. WTUV * Weight outside full weight range in self-calD WEIGHTIT * 0.0 3.0 Modify data weights function DOCALIB -1.0 101.0 > 0 calibrate data & weights > 99 do NOT calibrate weights GAINUSE SN table to apply DOPOL -1.0 10.0 If >0 correct polarization. PDVER PD table to apply (DOPOL>0) BLVER BL table to apply. FLAGVER Flag table version OUTFGVER 0.0 Output FG table version DOBAND -1.0 10.0 If >0 apply bandpass cal. Method used depends on value of DOBAND (see HELP file). BPVER Bandpass table version SMOOTH Smoothing function. See HELP SMOOTH for details. DOTV * -4096.0 4096.0 Display residuals on TV ? 0 -> no, 1 -> after each major cycle and each full Clean, -1 only after each full Clean. If you can, do at least -1. DOWEIGHT * 0.0 Rescale weights by DOWEIGHT for editing display only DOTWO * -1.0 1.0 True => do second observable plot of main baseline for display only BADDISK -1.0 1000.0 Disks to avoid for scratch. BPARM Subarray weight factors CPARM Subarray ref. ant. ---------------------------------------------------------------- SCIMG Type: Task Use: Self calibration loop. This task is very similar to SCMAP except that it allows the option of imaging with multiple fields. This task will do multiple iterations of self-calibration and imaging optionally starting with a one component model (SMODEL). Each iteration consists of 1) a visibility based imaging and Clean deconvolution (MX like), 2) determination of the appropriate number of Clean components and self-calibration uvrange, and 3) self-calibration of the visibility data based on the new model. A final imaging and deconvolution is then done on the final uvdata. The products of this task are a (multi-field) dirty beam, a (multi-field) Clean image and a calibrated set of uv data. Interactive data editing is now available as well. Both the calibrated input data and the residual data are displayed. The former is used for editing. This forces the task to run as an interactive task; the AIPS session that started it is frozen until SCIMG finishes. If you need to TELL SCIMG something, you must use a second interactive AIPS session and set NUMTELL to the SCIMG AIPS number. This nuisance is one of the reasons why we recommend using at least the TV option at the self-cal loop point (DOTV = -1). Adverbs: INNAME.....Input UV data file (name). Standard defaults. This should be a single source file with all prior calibration and editing done.. INCLASS....Input UV data file (class). Standard defaults. INSEQ......Input UV data file (seq. #). 0 => highest. INDISK.....Input UV data file disk drive #. 0 => any. OUTNAME....Output image name. Standard defaults. There will be output ICL001 and IBM001 images. The output Clean image will be used during execution as the residual image. OUTSEQ.....Output sequence number. OUTDISK....The disk drive # of output images. 0 => highest with space (note: map and Beam go on same disk. OUTSEQ.....Output sequence number. OUT2NAME...Output UV file name (name). Standard defaults. The output uv data file is used as a scratch file during execution. OUT2CLASS..Output UV file name (class). Standard defaults. OUT2SEQ....Output UV file name (seq. #). 0 => highest unique OUT2DISK...Disk drive # of output UV file. 0 => highest disk number with space The following control imaging: CELLSIZE...(X,Y) pixel separation in asec. IMSIZE.....(X,Y) The desired size of the Clean image; must be a power of 2. NFIELD.....The number of fields to map in the antenna beam. Up to 4096 are allowed. Note that only 64 fields may be described in adverbs, but 4096 are allowed. If you want to set Clean boxes in advenace for more than the first field, or wish to specify RASHIFT, DECSHIFT, or FLDSIZE for fields > 64, you must use the BOXFILE option. DO3DIMAG...> 0 => make the images by shifting the tangent point to the field center. This is at least marginally more accurate for significant shifts than the "u-v plane faceting" done with DO3DIM <= 0. Note that the DO3DIM false was made rather more accurate in late April, 2009 by changing how the data are gridded with a facet- and w-dependent correction to the u,v used for gridding. FLDSIZE....(X,Y) field size in pixels for the component search during Cleaning; one per field. Should be in the range 32X32 to 8192X8192. Output image size will be increased to the next highest power of two (or IMSIZE if that is greater), but only the region specified will be searched for components. Default is IMSIZE-10. Set FLDSIZE(1,i) and FLDSIZE(2,i) = -1, if you want there to be NO clean box initially in field i. TV options may be used to delete, change and create Clean boxes interactively. The BOXFILE option and the NVSS WWW server may help in entering these values;see below. RASHIFT....RA shift of the phase center of each field from the tangent point of the uv data in asec. Map center = tangent point + shift. If X>0 shifts map center to east. NOTE: RASHIFT is a shift in RA scaled by cos (Dec_0) as Ra_new(i) = RA_0 + RASHIFT(i) / cos (Dec_0) where _0 => the tangent point in the uv data. This is a change for 15OCT99 from shifts in -SIN projection (which do not work for -NCP data and large angles). If the UV data have been rotated then RASHIFT and DECSHIFT refer to X and Y in the new coordinate system. The BOXFILE option and the NVSS WWW server may help in entering these values;see below. DECSHIFT...Declination shift of map center from tangent point of each field in asec. Map center = tangent point + shift. If Y>0 shifts map center to north. The BOXFILE option and the NVSS WWW server may help in entering these values;see below. UVTAPER....(U,V) Gaussian taper (kilo-lambda) at 30% level UVRANGE....(Minimum,Maximum) baseline (kilo-lambda) in map. Note: this value is used only in imaging. The uv range used in self-calibration is set by the task. UVWTFN.....Weighting function of (u-v) plane in 2 character code. If the first character is N use "natural" weighting (no variation due to local density), otherwise use "uniform" weighting (weights are modified by local density of samples - first letter C - or weights under control of UVSIZE, UVBOX, UVBXFN, and ROBUST). If the second character is the letter O, all weights are set to one, and if the second letter is V, all weights are set the their fourth root, before any use is made of them. UVSIZE.....Size of the array used to count samples for uniform weighting. Does not have to be a power of two and can be smaller than or bigger than the image size. The default is the size of the first output image. ROBUST.....Briggs' "robustness" parameter. "Uniform" weights are tempered by a constant being added to the local density of weights. ROBUST = -4 is nearly pure uniform weighting, ROBUST = +4 is nearly pure natural weighting. Use of this option requires a second array in the "AP" memory and may therefore force the data to be sorted. The option is turned off if ROBUST < -7 and uniform weighting is turned off is ROBUST > 7. See HELP ROBUST. UVBOX......(U,V) box size for weighting. This is the support radius over which a sample is counted. I.e., the sample or its weight is counted over an area 2*UVBOX+1 cells on each side in the UV plane, where the UV cell size is (after correcting units) given by 1 / (UVSIZE(i) * CELLSIZE(i)). UVBXFN.....If UVBOX > 0, UVBXFN controls how the samples are counted as a function of u and v (UVBXFN < 0) or of radius (UVBXFN > 0). In the latter case, the function is 0 for radius > UVBXFN. Functions are pill box, linear, exponential, and Gaussian for ABS(UVBXFN) = 1-4, resp. 0 -> 1. See HELP UVBXFN. ROTATE.....Rotation angle to be applied in degrees. ZEROSP.....(1)= zero spacing flux density for the polarization being processed. Zero spacing flux is placed at the center of image. (2)= FWHM size of major axis for Zero spacing flux component (in arc seconds). (3)= FWHM size of minor axis for Zero spacing flux (4)= Position angle (north through east, degrees) If (2) is zero, source is assumed bigger than image. (5)= the weight for zero spacing flux. XTYPE......Convolution function type in X-direction 1=Pill-box, 2=exponential, 3=Sinc, 4=Exp*Sinc, 5=Spheroidal, 6=exp*BESSJ1(x)/x. <= 0 or > 5 -> 5. YTYPE.....Convolution function type in Y-direction XPARM.....Array containing parameters for XTYPE. See HELP UVnTYPE when n=convolution type. YPARM.....Array containing parameters for YTYPE. GUARD.....Fraction of the x and y radius for which uv samples are not allowed. < 0 => just enough to avoid mathematical errors in the convolution. 0 => 0.3 * SQRT(taper weight at 0.3 from edge). The following control Cleaning: NBOXES.....Number (<=50) of rectangular search boxes to search on the first field; the Clean window in all other fields is given by FLDSIZE. 0 => use FLDSIZE to determine windows on field 1. CLBOX......A 4x50 array with the parameters of each box. 0 => use window specified in FLDSIZE. CLBOX(1,i)=-1 indicates a circle of radius CLBOX(2,i) pixels centered on (CLBOX(3,i), CLBOX(4,i)). CLBOX(1,i) >= 0 indicates a rectangular box. NOTE: CLBOX is not used to determine the size of the image to be made; IMSIZE or FLDSIZE must set the size of the image. BOXFILE....Input text file used to simplify the specification of large numbers of fields and/or large numbers of Clean boxes. To specify a field's parameters, put the letter F or f in column 1 followed by the field number, the X and Y FLDSIZE values, the RASHIFT amd the DECSHIFT for the field (separated by blanks). Any field specified in this way overrides the corresponding parameters given in the adverbs. Thus, F 2 450 450 -25.5 6.7 specifies that field 2 is to have a FLDSIZE of 450x450 with an RASHIFT of -25.6 and a DECSHIFT of 6.7 arcsec. If this is the only F card in the file, then fields 1 and 3 through NFIELD are set by the adverb values. As an alternative, a field may also be specified with a "coordinates" card having a C or c in column one. After the C, give the field number, the X and Y FLDSIZE values and the center Right Ascension (HH MM SS.S) and Declination (signDD MM SS.S) separated by blanks. Thus C 2 450 450 11 34 45.67 -00 14 23.1 specifies that field 2 is to have a FLDSIZE of 450x450 with a center RA of 173.6902917 degrees and a center Declination of -0.23975 degrees. All 9 numbers must be given; the sign is optional for positive declinations and is given only on the degrees term. To set Clean boxes, specify one box per line, as field blc-x blc-y trc-x trc-y (5 integers) e.g. 1 200 205 220 222 1 230 232 240 241 2 100 100 130 121 ... or circular "boxes" as field -1 radius center-x center-y (5 ints) e.g. 001 -1 10 210 214 001 -1 5 235 237 .... Column 1 must contain a numeric character (part of the field number); otherwise the line is treated as a comment (or an F or C line). Fields with no boxes specified default to the size specified by IMSIZE and FLDSIZE (see above and including FLDSIZEs read from this file). If any boxes for field one appear in the file, then this option overrides NBOXES and CLBOX. Otherwise, those adverbs are used for field 1. E.g. BOXFILE 'FITS:BOXES' The number of Clean boxes per field is limited to min [ 4096, (64*4096)/NFIELD ] If BOXFILE = ' ', NBOXES and CLBOX apply unchanged as do the FLDSIZE, RASHIFT, and DECSHIFT adverbs. The NVSS WWW server may help in preparing these values;see below. The BOXFILE option is essential when NFIELD > 64. OBOXFILE...Output text file to record the Clean boxes used. Each time a TV REBOX or TVBOX is selected the file is rewritten (as the TV interaction ends) with all of the Clean boxes currently in force for all fields GAIN.......The Clean loop gain. 0 => 0.10. Can be changed by TELL. FLUX.......Stop Clean when abs(resid. image max) < FLUX (Jy). IF FLUX < 0 then Clean stops at first negative Clean Component. Can be changed by TELL. SCIMG may lower this value and in general uses 1.0 times the previous RMS residual unless a lower value has been set. MINPATCH...Minimum half width of the portion of the beam which is used in the AP minor Clean. Can be changed by TELL. NITER......Clean iteration limit. This is an upper limit as each Clean may stop prior to this limit. The final Clean continues until NITER Clean components are Found. Can be changed by TELL. 0 => 300 BMAJ.......The FWHM (asec) major axis of the restoring beam. If 0; value obtained from fitting to the beam. Can be changed by TELL BMIN.......The FWHM (asec) minor axis of the restoring beam. Can be changed by TELL. BPA........The position angle in the unrotated image of BMAJ. Can be changed by TELL. OVERLAP....If 1, then restore components from each field to all fields that they overlap. If 2, choose a pattern of Cleaning fields designed to reduce the effects of having the same object in > 1 field's Clean boxes. If OVERLAP>0, the output CC files will have been merged. If OVERLAP=2, you can control which field is Cleaned next, but only if the task runs interactively (set DOWAIT=TRUE before GO IMAGR). ONEBEAM....> 0 => do only one beam pattern per resolution for either value of DO3DIMAG. Note that the facet beams are different, but it has been argued that they are not enough different to matter with uv-plane based Cleans. ------------------------ SUGGESTION: Use OVERLAP=2 and ONEBEAM=FALSE at the start of major multi-facet Cleans and run them until the high dynamic range signals have been Cleaned. Then restart with those Clean components using OVERLAP=1 and ONEBEAM=TRUE for the weaker components in a more efficient Clean. NOTE that you must be careful to Clean each source region in only one facet if you use OVERLAP=1 mode. Multi-scale Clean is not available in OVERLAP < 2. ------------------------ FACTOR.....FACTOR>0 causes deeper Clean in each major cycle, speeding Clean, maybe "eating" extended structure. FACTOR=0 => the normal Clark Clean. FACTOR=-0.3 is good for deep Cleans of extended structure. Can be changed by TELL. MAXPIXEL...The maximum number of pixels that are searched for components inside the ``AP'' in each major cycle. < 3000 => 20050. This number affects the cpu usage significantly. Too many causes the task to search over many points it will never use. Too few causes the task to do many more small major cycles, also at great expense. Use this with great caution, but big wins are possible using larger sizes on very large cleans. CMETHOD....This determines the method used to compute the model visibility values. 'DFT' uses the direct Fourier transform, this method is the most accurate. 'GRID' does a gridded-FFT interpolation model computation. ' ' allows the program to use the fastest method. Can be changed by TELL: once set to 'DFT' it can no longer be changed, however. The following control self-calibration: NMAPS......Number of self-calibration loops. SMODEL.....A single component model to be if SMODEL(1)>0 SMODEL(1) = flux density (Jy) SMODEL(2) = X offset in sky (arcsec) SMODEL(3) = Y offset in sky (arcsec) SMODEL(4) = Model type: 0 => point model (others NYI) REFANT.....The desired reference antenna for phases. SOLINT.....The solution interval (min.) 0 => data interval which may or may not be a good idea. SCIMG doubles SOLINT when(if) it switches from phase only to amp & phase solutions. APARM......Task enrichment parameters: APARM(1)...Minimum number of antennas allowed for a solution. < 3 => 4. APARM(2)...If >0 then constrain the mean gain modulus of the calibration applied to be unity. APARM(3)...If > 0 then average RR, LL. APARM(5)...If > 0 then make a combined solution for the IFs; if <= 0 then make separate solutions. APARM(6)...Print flag, 0=none, 1=time,some info including the antenna signal to noise ratio, 2=lots. APARM(7)...The minimum allowed solution signal-to-noise ratio. 0 => 5 APARM(8)...SIGMA. Each Clean can be restarted using a subset of the components from the previous Clean. All merged components brighter than SIGMA*(residual_RMS) will be reused. 0 => 10 APARM(9)...Averaging time used when data are read into the interactive editing tool in minutes. <= 0 => SOLINT. APARM(10)..Amplitude solutions may be box-car smoothed wrt the phase solutions by APARM(10) minutes. SOLTYPE....Solution type: ' ' => normal least squares, 'R ' => as ' ' with robust iteration 'L1 ' => L1 solution; a weighted sum of the moduli of the residuals is minimized. The computed gain solutions are less influenced by wild data points, but there is some loss of statistical efficiency. See [F.R. Schwab, VLA scientific Memo #136] for further details. 'L1R ' => as 'L1' with robust iteration 'GCON' => least squares which may include gain constraint. 'GCOR' => as 'GCON' with robust iteration The robust versions iterate the solution, discarding data that does not fit the current solution well enough. They should be less disturbed by bad data, but will be slower. SOLMODE....Solution mode: 'A&P ' => amplitude and phase. 'P ' => phase only 'P!A ' => phase only (no amplitude information) 'GCON' => amplitude and phase with constraints on amplitude. This mode requires setting SOLTYPE='GCON', uses GAINERR and SOLCON may be used. ' ' => start with phase only and switch to amp and phase. SOLCON.....Gain constraint factor; a value larger than 0 will increase the strength of the amplitude constraint in gain constrained solution with SOLMODE='GCON' ANTWT......Antenna weights. These are additional weights to be applied to the data before doing the solutions, one per antenna. Use PRTAN to determine which antenna corresponds to each antenna number. 0 => 1.0 GAINERR....Estimates of the standard deviation of the modulus of the gains for each antenna. These are used ONLY if SOLMODE and SOLTYPE='GCON'. The solution will attempt to make the standard deviation of the modulus of the antenna gains match these values so accurate values are essential. WTUV.......The weighting factor for data outside of the uv range given full weight. <= 0 => 0.05. Warning: SCIMG sets its own UVranges for self-cal and it is a bad idea to have WTUV near zero when these ranges are small. WEIGHTIT...If > 0, change the data weights by a function of the weights just before doing the solution. Choices are: 0 - no change weighting by 1/sigma**2 1 - sqrt (wt) weighting by 1/sigma may be more stable 2 - (wt)**0.25 3 - change all weights to 1.0 DOCALIB....If true (>0), calibrate the data using information in the specified Cal (CL) table for multi-source or SN table for single-source data. Also calibrate the weights unless DOCALIB > 99 (use this for old non-physical weights). GAINUSE....Version number of the SN table to apply. 0 => highest. DOPOL......If > 0.5 then correct data for instrumental polarization as represented in the AN or PD table. This correction is only useful if PCAL has been run or feed polarization parameters have been otherwise obtained. See HELP DOPOL for available correction modes: 1 is normal, 2 and 3 are for VLBI. 1-3 use a PD table if available; 6, 7, 8 are the same but use the AN (continuum solution) even if a PD table is present. PDVER......PD table to apply if PCAL was run with SPECTRAL true and 0 < DOPOL < 6. <= 0 => highest. BLVER......Version number of the baseline based calibration (BL) table to appply. <0 => apply no BL table, 0 => highest. FLAGVER....Specifies the version of the flagging table to be applied on initial input. OUTFGVER...Flag table version to be used on output for both single- and multi-source data sets. If OUTFGVER is <= 0 or greater than FGmax (the previously highest FG version number), then a new FG table will be created for the new flags with version FGmax+1. This new table will also contain the flags applied on input (if any) from FG version FLAGVER. If OUTFGVER specifies a pre-existing FG version, then the input flags are not copied even if OUTFGVER and FLAGVER are not equal. DOBAND.....If true (>0) then correct the data for the shape of the antenna bandpasses using the BP table specified by BPVER. The correction has five modes: (a) if DOBAND=1 all entries for an antenna in the table are averaged together before correcting the data. (b) if DOBAND=2 the entry nearest in time (including solution weights) is used to correct the data. (c) if DOBAND=3 the table entries are interpolated in time (using solution weights) and the data are then corrected. (d) if DOBAND=4 the entry nearest in time (ignoring solution weights) is used to correct the data. (e) if DOBAND=5 the table entries are interpolated in time (ignoring solution weights) and the data are then corrected. BPVER......Specifies the version of the BP table to be applied. <0 => no bandpass correction done. SMOOTH.....Specifies the type of spectral smoothing to be applied to a uv database . The default is not to apply any smoothing. The elements of SMOOTH are as follows: SMOOTH(1) = type of smoothing to apply: 0 => no smoothing To smooth before applying bandpass calibration 1 => Hanning, 2 => Gaussian, 3 => Boxcar, 4 => Sinc To smooth after applying bandpass calibration 5 => Hanning, 6 => Gaussian, 7 => Boxcar, 8 => Sinc SMOOTH(2) = the "diameter" of the function, i.e. width between first nulls of Hanning triangle and sinc function, FWHM of Gaussian, width of Boxcar. Defaults (if < 0.1) are 4, 2, 2 and 3 channels for SMOOTH(1) = 1 - 4 and 5 - 8, resp. SMOOTH(3) = the diameter over which the convolving function has value - in channels. Defaults: 1,3,1,4 times SMOOTH(2) used when input SMOOTH(3) < net SMOOTH(2). DOTV.......Display residuals on TV channel 1. > 0 => display field number DOTV initially. Can be changed by TELL. When using this option, you may interact with the residual images at the end of each major cycle of Clean, selecting which field is examined in what window, resetting the Clean boxes, and stop the Cleaning of the current self-cal loop. SCIMG additional option: DOTV < or > 0 => display field number abs(DOTV) at the end of each Clean and interact with that image including UV data editing options. If DOTV < 0, the only display is at the end of each Clean else both are done. DOTV = 0 => no TV display. It is strongly recommended that you use at least DOTV = -1. That display lets you change parameters including DOTV to resume the display during Clean. DOWEIGHT...The display of error bars in the editing phase depends on the data weights being 1/(sigma**2) in 1 (Jy**2). Set DOWEIGHT to get the data weights into this scale, multiplying the input weights by DOWEIGHT. 0 -> 1. DOTWO......> 0 (true) means to do the secondary plot of a second observable (phase, amplitude, diff amplitude) from the primary baseline in the editing phase. <= 0 means to plot only the primary observable used for the editing. True is highly recommended. BADDISK....This array contains the numbers of disks on which it is desired that scratch files not be located. BADDISK has no effect on input and output data. BPARM......Subarray relative weight factors; applied to all data. CPARM......Subarray refence antenna (2->10 only). ---------------------------------------------------------------- SCIMG: Imaging - self-calibration loop task. Documentor: W. D. Cotton, NRAO Related Programs: CALIB, MX, EDITR This task will do multiple iterations of self-calibration and imaging optionally starting with a one component model (SMODEL). Each iteration consists of 1) a visibility-based imaging and Clean deconvolution (like IMAGR), 2) determination of the appropriate number of Clean components and self-calibration uvrange, and 3) self-calibration of the visibility data based on the new model. A final imaging/deconvolution is then done using the solution which gave the best RMS/(sum CC) residual. This solution is then used to produce the final output uvdata. Only I polarization data is imaged but the resulting self-calibrated uvdata will contain properly calibrated data for all input polarizations. For spectral line data a "continuum" data set should be formed from selected line channels using SPLIT, UVCOP etc. and used as the input to SCIMG. The resultant image can then be used with CALIB to calibrate the line data set This task uses a number of techniques to improve the efficiency and stability of the self-calibration process. After the first Clean, future Cleans may be restarted using some number of components from the previous Clean. In addition, the minimum residual level is set the RMS residual of the previous Clean. The number of Clean components used in the next Clean is determined from the value of APARM(8). The previous CC table is first merged and then all components brighter than APARM(8) times the RMS residual of the previous Clean are reused. Depth of Clean: Each self-calibration iteration SCIMG decides on the depth of the Clean. The Clean proceeds until the absolute value of the residual is the RMS residual of the previous iteration. This can be modified by using adverbs NITER and FLUX. Cleaning never proceeds longer than NITER iterations and FLUX will never be increased. Deeper Cleans can be forced by setting FLUX to a small, but positive value and NITER to a sufficiently large number. The final Clean is up to NITER components with no minimum flux density level test. The number of iteration is not a totally accurate determination of the depth of Clean as the CC table is merged each cycle and some components will be reused. Thus, the Clean is deeper than would be obtained from the same number of components without merging. Both NITER and FLUX may be adjusted interactively during the self-cal TV interaction. Uv Baseline Range: The range of baseline lengths (UVRANGE) specified in the input is only used in the imaging step. In each iteration of self-calibration the appropriate uv range and number of Clean components to use is determined heuristically. The Clean components are merged and all components up to the first negative one are used. The corresponding uv range for self-calibration is determined from comparison of the sum of the flux in the Clean model and the distribution of average amplitudes as a function of baseline length. Baselines longer that the longest with an average higher that the summed Clean model are given full weight. A slight tolerance (1 sigma) is used to allow for noise. Baselines outside of the range given full weight are weighted by the factor UVWT. Note there is no default and UVWT=0 causes this data to be completely ignored. Convergence: The test for convergence is based on the RMS residual value (ignoring the outer pixels) of the Clean image divided by the sum of the Clean flux. Convergence is declared when either the convergence measure increases by more than 10 percent or if more than three self-calibration cycles has elapsed since the best solution. When convergence is obtained the solution with the best convergence measure is used to produce the final image and uv data. Solution Mode: The solution type can be set to either 'P', 'P!A', 'A&P' or ' '. The first three will cause only solutions of the appropriate type to be performed. If SOLMODE is set to ' ' the self-calibration solutions are initially done using only phase until the convergence measure no longer shows improvment. The last self-calibration solution is then applied to the input data and a new scratch file is filled with the result. Further processing uses this data. After the mode switch amplitude calibration is enabled and all selected IFs and polarizations are averaged in the self-cal solutions. The minimum number of antennas is changed to 4 if it is initially less and gain constraint is enabled (APARM(2)). Also, the solution interval (SOLINT) is doubled; or, if an initial value of 0 was given 30 seconds is used. Restarting: If SCIMG previously terminated normally then the output uv data is suitable for input for another execution. If SCIMG did not terminate normally then the last SN table produced can be used as the starting calibration (see DOCALIB and GAINUSE). This method can recover results up to a switch between phase only and amplitude and phase calibration (see discussion above on SOLMODE). After a mode switch the working data is written to the output file. A restart can then use the output of the previous run and the last SN table attached to it. If SCIMG terminated normally there will be no SN tables attached to the output. The output Clean image should always have a CC version 2 which is a copy of the latest, merged CC table. This table can always be used with CALIB to produce suitable input for SCIMG. Limiting messages: SCIMG can produce a large quantity of messages. These messages can be limited using the verb MSGKILL. MSGKIL 4 will result in only the most important messages. **************************************************************** *********************** TV DISPLAYS ************************ **************************************************************** ********************** During Clean: *********************** The TV display may be used to follow the progress of your imaging and Cleaning. If you set DOTV > 0, the dirty image of field DOTV will be displayed before Clean begins and the residual image of the selected field will be displayed after each major Clean cycle. When the image is displayed, a menu of interactive options is also displayed. Move the TV cursor to a desired option, and press TV button A, B, or C. To get help on the message screen about an option, move the cursor to that option and press TV button D. The selected option is highlighted in a different color. If you select no options in 30 seconds, SCIMG will continue without you until the end of the next major cycle. Interactive options do not appear on the final display which is either of the dirty image (NITER = 0) or the Clean image with components restored. If you forget to turn on the TV display - or turn it off after starting SCIMG - you may turn it back on with TELL SCIMG (say SHOW SCIMG in AIPS to see all the TELL parameters that you may send to SCIMG after it has started). The interactive options appear in two columns. The left column offers: ---------------- | OFFZOOM | turn off any zoom magnification | OFFTRAN | turn off any black & white enhancement | OFFCOLOR | turn off any pseudo-coloring | TVFIDDLE | as in AIPS, allows zoom, pseudo-color contours or black and white enhancement | TVTRAN | black and white enhancement as in AIPS | TVPSEUDO | many pseudo-colorings as in AIPS | TVFLAME | flame-like pseudo-colorings as in AIPS | TVZOOM | interactive zoom magnification and center | CURVALUE | display image intensity, pixel x/y at cursor | SET WINDOW | set sub-image display window | RESET WINDOW | re-set display window to full image | TVBOX | set number of Clean boxes and their parameters interactively | REBOX | modify and add Clean boxes for this field ---------------- When a field is displayed, the pixel increments are chosen to load the full field to the TV screen. The TV window is even forced to be bigger to show the image if needed and small fields are interpolated by up to a factor of 3. The Clean boxes for the field are displayed in a graphics overlay. You may select a smaller sub-image of the field for display in greater detail, but SCIMG does insist that the sub-image includes all Clean boxes for the field. You may use TVBOX or REBOX to create and modify the Clean boxes interactively. Note that these set the number as well as the type and parameters of the boxes. This is currently one of two interactive ways to set Clean boxes for fields numbered > 1. The other if the verb FILEBOX in AIPS. TVBOX: To set the number, type, and parameters of the Clean boxes for the displayed field with a TV graphics display of the boxes as they are being set. The terminal will issue instructions. While setting the lower left corner of each box for the first time, buttons A and B will mark the corner and switch to setting the upper right corner of the box. Button C will change the rectangular box to a circular one and button D will exit. There will be no output boxes if button D is hit in this state on the first box. Similarly, while first setting the center of a circular box, buttons A and B switch to setting the radius, C switches back to a rectangular box, and D exits deleting that incomplete box. While setting or re-setting the upper right corner or radius of the box or re-setting the lower left corner or center, button A marks the current corner and switches to the other corner (or marks and switches between radius and center), button B marks the current corner and switches to the next (new) box, button C marks the current corner and switches to a search mode leading to the resetting of a previous box, and button D exits keeping the current and previous boxes with their current settings. In search mode, move the cursor to any lower left or upper right corner of any already set rectangular box or the center or any point on the circumference of an already set circular box and press button A or B to reset that corner or push button C to go on to the next box. As usual button D exits. REBOX is TVBOX started with the current boxes in a resetting mode. The right-hand column offers the options: ------------------- | CONTINUE Clean | Continue Cleaning now, not waiting for the timer to expire | STOP CleanING | Declare the Clean of this channel done, restore components and write the output | TURN OFF DOTV | Resume Cleaning now and turn off future TV displays | ABORT TASK | Drive a silver stake through SCIMG's heart without waiting for a full moon or even for midnight. ------------------- If you turn off the TV display, you may restart it with TELL from AIPS. **************************************************************** ******************** Before self-cal: ********************** **************************************************************** The TV display may be used also (or instead) to follow the progress of your imaging at the end of the Clean step before doing the next self-cal. If you set DOTV not= 0, the residual image of field DOTV will be displayed after Clean ends. When the image is displayed, a menu of interactive options is also displayed. Move the TV cursor to a desired option, and press TV button A, B, or C. To get help on the message screen about an option, move the cursor to that option and press TV button D. The selected option is highlighted in a different color. If you select no options in 30 seconds, SCIMG will continue without you until the end of the next major cycle of Clean (if selected) or until the end of the next Clean. If you forget to turn on the TV display - or turn it off after starting SCIMG - you may turn it back on with TELL SCIMG (say SHOW SCIMG in AIPS to see all the TELL parameters that you may send to SCIMG after it has started). The interactive options appear in two columns. The left column offers: ------------------ | OFFZOOM | turn off any zoom magnification | OFFTRANS | turn off any black & white enhancement | OFFCOLOR | turn off any pseudo-coloring | TVFIDDLE | as in AIPS, allows zoom, pseudo-color contours or black and white enhancement | TVTRAN | black and white enhancement as in AIPS | TVPSEUDO | many pseudo-colorings as in AIPS | TVFLAME | flame-like pseudo-colorings as in AIPS | TVZOOM | interactive zoom magnification and center | CURVALUE | display image intensity, pixel x/y at cursor | SET WINDOW | set sub-image display window | RESET WINDOW | re-set display window to full image | TVBOX | set number of Clean boxes and their parameters interactively | REBOX | modify and add Clean boxes for this field | EDIT DATA | select the data editing tool to view visibility data and current residuals and delete bad points | SET PARAMETERS | Reset various adverb values. | SWITCH TO A&P | Switch from phase-only to amplitude and phase ---------------- When a field is displayed, the pixel increments are chosen to load the full field to the TV screen. The TV window is even forced to be bigger to show the image if needed and small fields are interpolated by up to a factor of 3. The Clean boxes for the field are displayed in a graphics overlay. You may select a smaller sub-image of the field for display in greater detail, but SCIMG does insist that the sub-image includes all Clean boxes for the field. You may use TVBOX or REBOX to create and modify the Clean boxes interactively. Note that these set the number as well as the type and parameters of the boxes. The EDIT DATA selects a data editing tool described below. It is slow in starting up so do not select this option more than needed. SET PARAMETERS: Since SCIMG is run as an interactive task, TELLing it to change parameters requires a second AIPS session and some care. This option brings up a question and answer session that prompts you for all TELL parameters plus a couple other useful ones. Answer with a blank line (simple carriage return) to leave the parameter unchanged; answer with a Q or q to stop the questioning. The parameters are, in order, NMAPS, DOTV, SOLINT, APARM(10), NITER, APARM(9), APARM(8), FLUX, GAIN, FACTOR, MINPATCH, MAXPIXEL, BMAJ, BMIN, BPA, REFANT, WTUV, SOLTYPE, SOLMODE, SOLCON. If SOLMODE is already A&P due to a switch from P, do not change it. SWITCH TO A&P: If this option is offered, you may declare to SCIMG that enough phase-only iterations have been done and that it is time to do the switch to amplitude and phase. The option is offered only if SOLMODE = ' ' to begin with and, then, only if the switch has not already taken place. SCIMG applies the latest phase calibration to the input data moving them to another file. Then it doubles the SOLINT and does the remaining self-cals as A&P. If you want to ignore the previous phase cals (other than by their effect on the current Clean image), use SET PARAMETERS and change SOLMODE instead. TVBOX: To set the number, type, and parameters of the Clean boxes for the displayed field with a TV graphics display of the boxes as they are being set. The terminal will issue instructions. While setting the lower left corner of each box for the first time, buttons A and B will mark the corner and switch to setting the upper right corner of the box. Button C will change the rectangular box to a circular one and button D will exit. Similarly, while first setting the center of a circular box, buttons A and B switch to setting the radius, C switches back to a rectangular box, and D exits deleting that incomplete box. While setting or re-setting the upper right corner or radius of the box or re-setting the lower left corner or center, button A marks the current corner and switches to the other corner (or marks and switches between radius and center), button B marks the current corner and switches to the next (new) box, button C marks the current corner and switches to a search mode leading to the resetting of a previous box, and button D exits keeping the current and previous boxes with their current settings. In search mode, move the cursor to any lower left or upper right corner of any already set rectangular box or the center or any point on the circumference of an already set circular box and press button A or B to reset that corner or push button C to go on to the next box. As usual button D exits. REBOX is TVBOX started with the current boxes in a resetting mode. The right-hand column offers the options: ------------------- | CONTINUE SELFCAL| Continue self-cal now, not waiting for the timer to expire | STOP SELFCAL | Declare the self-cal done, do a deeper Clean and write out the final images and calibrated data set | TURN OFF TV | Resume processing now and turn off future TV displays | ABORT TASK | Drive a silver stake through SCIMG's heart without waiting for a full moon or even for midnight. ------------------- If you turn off the TV display, you may restart it with TELL from AIPS. That will require using a second AIPS session since the AIPS session that started SCIMG is suspended until it ends. **************************************************************** ********************* While editing: *********************** **************************************************************** SCIMG implements a version of task EDITR as a TV graphic editor for uv data using the uv data themselves and the current residuals. It works with the XAS-TV display graphics planes (7 of them) to allow you to flag uv data based on their values. It does not change the input data set, but will write a flag table used in the next step of self-cal. The editor averages spectral channels and over a specified time interval as it reads the data set(s). It attempts to read the entire data set into the pseudo-AP memory when if starts up. If it cannot fit all the data, it attempts to read just one IF at a time and/or all baselines to one antenna at a time. In that case, when you switch IFs or main antennas, the editor has to reads in the next IF or set of baselines. The editor will tell you as it starts whether "All data will reside in memory" or various other combinations. Judicious choices of APARM(9) can help the task to read all selected data and thus to be more efficient There are 6 parts to the editor's display: (1) A menu of operations displayed in two columns, one each at the left and right sides of the screen. When the menu is displayed, move the cursor to the desired item and press buttons A, B, or C. To get on-line help in the message window about a given option, move the cursor to the desired menu item and press button D. (2) A plot at the bottom of the screen in a bright color (usually) of the data which may be actively edited at present. It is of the chosen type for the selected baseline, polarization, and IF and is limited in time range by the current frame (which can be all or a portion of the total time range). Flagged data are shown in a different color. The time range of the frame may be made small to expand the time axis, but may also be made so large as to cause serious crowding of the plotted data points. (Increase your XAS window width to increase the plot scale.) (3) A plot above the edit area plot in the same bright color of the data from the selected baseline, polarization, and IF. This plot is in a second observable (e.g. if amplitude is in the edit plot, phase is often the second observable). Data in this second area may not be used for editing but should be helpful in choosing which data to delete in the edit area. Flagged data are shown in a different color. This plot may be suppressed by adverb DOTWO. (4) 0-10 plots of data of the current data type, IF, and polarization for a list of 0-10 other baselines to the main antenna are shown above the second plot. They are shown for comparison using another color, while flagged data are shown in a different color. (5) Data from the Clean residuals will be shown in another color in each of the windows (2, 3, 4) above. This display may be turned off and on with a menu item. (6) Several text areas also appear including (a) the start and end times for the current frame's time axis, (b) the selected data type, IF, and polarization at the bottom of the screen, (c) the antenna shown in each plot at the top right of each plot, (d) the current all-IF, all-polarization, and all-antenna flags, (e) the y-axis tick values on each of the frame plots, and (f) while interactively setting time and/or value ranges, the time and/or value to which you are currently pointing and the associated source name. You may change the size of the XAS window at any time. The editor will not allow it to become too small, but will adjust its display for all reasonable sizes. The left-hand menu can contain ------------------- | FLAG TIME | To delete one time at a time. | FLAG TIME RANGE | To delete one or more time ranges. | FLAG BELOW | To delete all displayed times with data below a cutoff value. | FLAG ABOVE | To delete all displayed times with data above a cutoff value. | FLAG AREA | To delete one or more areas in the data-value - time plane. | FLAG POINT | To delete one sample at a time using both horizontal and vertical cursor position. | FLAG FAST | To delete samples using only mouse clicks | ENTER AMPL RNG | To select the display range for amplitude plots. Use 0 -1 for 0 to antenna maximum and 0 0 for min to max. | ENTER PHASE RNG | To select the display range for phase plots. | ENTER DAMP RNG | To select the display range for plots of the amplitude of the visibility minus a running vector average visibility. | PLOT ERROR BARS | To plot error bars based on data weights | SET SCAN LENGTH | To set the averaging time used to determine the running average in seconds. | LIST FLAGS | To list all flags now in the Flag Command table. | UNDO FLAGS | To undo one of the flag operations in the FC table | REDO FLAGS | To reapply all remaining flags after one or more have been undone (see note below) | SET REASON | To set the 24-character "reason" string to be put in the uv-data flag table | USE EXPERT MODE | To control the task from the keyboard instead of the menu. | HOLD TV LOAD | To stop updating the TV display with every change of parameter; change several, then select | DO TV LOAD | To update the TV display now and with each change of display parameter. | REPLOT | To do the current plot over again, recomputing the differences from the running mean if appropriate. | EXIT | To exit editing, moving the FC table to a uv-data FG table | ABORT | To exit editing, deleting the FC table ------------------- The right-hand menu can contain ------------------- | NEXT CORRELATOR | To switch to viewing the next correlator, switching to the other polarization and, if needed, incrementing the IF. | SWITCH POLARIZ | To switch to viewing and editing the other polarization. | SWITCH ALL POL | To switch functions from applying to one polarization to applying to both polarizations or vice versa. | ENTER IF | To select which IF is viewed and edited. This can force a read of data if all IFs did not fit in memory. | SWITCH ALL IF | To switch functions from applying to one IF to applying to all IFs or vice versa. | SWITCH ALL TIME | To switch FLAG ABOVE and FLAG BELOW between all times and the time range of the frame | ROTATE ALL ANT | To rotate functions from applying to (a) one baseline, (b) all baselines to the main antenna, and (c) all baselines. | ENTER ANTENNA | To select the main antenna, baselines to which are displayed on the screen. | ENTER OTHER ANT | To select up to 11 other antennas to define the baselines to be displayed; enter 10 numbers, 0's are then ignored (to plot 5 enter the 5 plus 6 0's). The first one is used for the edit area. | NEXT BASELINE | To rotate the list of other antennas, selecting the next one for the edit area. | NEXT ANTENNA | To select a new main antenna, one higher than the current main antenna. The "others" MAY also be adjusted. | PLOT ALL TIMES | To display all data for the selected baselines. | SELECT FRAME | To select a window into the current data interactively. | NEXT FRAME | To select the next time-range window of the same size as the current frame. | PREVIOUS FRAME | To select the previous time-range window of the same size as the current frame. | SHOW AMPLITUDE | To display and edit amplitudes. | SHOW PHASE | To display and edit phases. | SHOW DIFF AMPL | To display and edit the amplitudes of the vector difference between the sample and its running mean | SHOW ALSO AMPL | To display amplitudes of the edit baseline for reference with the phase or difference amplitude edit window. | SHOW ALSO PHASE | To display phases of the edit baseline for reference with the amplitude or difference amplitude edit window. | SHOW ALSO DAMP | To display difference amplitudes of the edit baseline for reference with the phase or amplitude edit window. | TV ZOOM | To alter the display zoom used while in the flag functions. | OFF ZOOM | To turn off any zooming. | 2ND UV OFF | To disable the display of the residual uv data set. | 2ND UV ON | To enable the display of the residual uv data set. ------------------- The menus will not show all of these options every time. The HOLD TV LOAD option is shown until invoked, and then is replaced with the DO TV LOAD. When that is invoked, the HOLD TV LOAD option reappears. The SWITCH POLARIZ and SWITCH ALL POL options appear only if there are two polarizations in the data. The ENTER IF option appears only if there is more than one IF in the data and the SWITCH ALL IF option appears only if there is more than one IF and all IFs fit in the program memory. Only one of the three SHOW ALSO choices appears at any one time. Plots of the difference between the visibility and its running mean can be particularly sensitive to short term disturbances while ignoring slow changes due to gradually changing source structure and the like. The running mean is not carried between sources and, as a result, is not normally carried across scan boundaries. Note that value-dependent flagging (FLAG BELOW, ABOVE, AREA) use the values currently plotted to make a list of value-independent flag commands (i.e., a single time for the specified antennas, IFs, polarizations, etc.). When a value-dependent FLAG operation is undone (UNDO FLAGS) or redone (REDO FLAGS), it is these value-independent flags which are undone or redone. You may have to undo more commands and then repeat FLAG commands to get the results you could have gotten by doing the now desired value-dependent command in the first place. You need also to be careful with the ROTATE ALL ANT setting with these value-dependent commands. If one baseline is set, then the commands only apply to the current baseline. If one antenna is set, the commands apply to all baselines to the current main antenna, while if all antennas is set, the commands apply to all baselines. The first two set a clip level, below or above which data are deleted, based on the value of the observable in each baseline independently. The FLAG AREA command, however, only looks at the values of the observable in the main edit baseline and flags those samples from all applicable baselines. Be careful when choosing EXIT versus ABORT. The former applies the flag commands to a flag table attached to the input uv data, the latter causes the flag commands to disappear without a trace. The colors used by EDITR are those of the various graphics planes when it begins to run. You may change them with the AIPS verb GWRITE to more desirable colors. The planes are: Plane Default RGB Use 1 1.00 1.00 0.00 Main editing and secondary windows 2 0.06 1.00 0.00 Comparison baseline data windows 3 1.00 0.67 1.00 Menu highlight 4 0.00 1.00 1.00 Edit and frame window boundaries 5 1.00 0.18 0.18 Flagged data in all windows 6 0.60 0.60 1.00 Menu foreground 7 1.00 0.80 0.40 Second uv data set if present You may wish to change the colors to ones that you can see better. In "expert" mode, you are prompted with a set of 4-character codes. You type in the letter within that code that is shown in upper case (left-justified with a carriage return) to get the desired function. The expert functions allowed are Code Prompt Full menu OP name T Time FLAG TIME R Rang FLAG TIME RANGE B Belo FLAG BELOW A Abov FLAG ABOVE E arEa FLAG AREA O pOin FLAG POINT Q Quik FLAG FAST L List LIST FLAGS U Undo UNDO FLAGS S baSl NEXT BASELINE C nCor NEXT CORRELATOR N Nant NEXT ANTENNA F Fram SELECT FRAME M aMpl SHOW AMPLITUDE P Phas SHOW PHASE D aDif SHOW DIFF AMPL X eXit EXIT EXPERT MODE H Help THIS HELP LIST although some may be suppressed depending on what is currently displayed. ------------------------------------------------------------------------