; IMFRING ;--------------------------------------------------------------- ;! large image delay fitting with IM2CC and OOFRING ;# PROCEDURE CALIBRATION AP UV OOP ;----------------------------------------------------------------------- ;; Copyright (C) 2017 ;; 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 ;----------------------------------------------------------------------- IMFRING LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC IMFRING: Determines antenna delays from large image Input uv data. INNAME UV file name (name) INCLASS UV file name (class) INSEQ 0.0 9999.0 UV file name (seq. #) INDISK 0.0 9.0 UV file disk drive # input image IN2NAME Large image name (name) IN2CLASS Large image name (class) IN2SEQ Large image name (seq #) IN2DISK Large image name (disk) BLC 0.0 4096.0 Bottom left corner of image 0=>1 TRC 0.0 4096.0 Top right corner of image 0=>max allowed ICUT 0.0 Include all points > ICUT in absolute value only FLUX Discard all points < FLUX NX 1.0 Number panels in X NY 1.0 Number panels in Y OUTNAME name to use for temporary files (CC, OOSUB output) OUTDISK Disk to put subimages/CCs Solution control adverbs: DOKEEP -1.0 1.0 > 0 -> keep divided us data Data selection (multisource): BCHAN 0.0 2048.0 Lowest channel number 0=>all ECHAN 0.0 2048.0 Highest channel number ANTENNAS Antennas to select. 0=all DOFIT Subset of ANTENNAS list for which solns are desired. UVRANGE Range of uv distance for full weight WTUV Weight outside UVRANGE 0=0. WEIGHTIT 0.0 3.0 Modify data weights function INVERS -1.0 46655.0 CC file version #. ONEFREQ -1.0 1.0 > 0 => CC model from only one frequency (group) CMETHOD Modeling method: 'DFT','GRID',' ' Solution control adverbs: REFANT Reference antenna SEARCH 0.0 1000.0 Prioritized reference antenna list - supplements REFANT - but only if APARM(9)>0 SOLINT Solution interval (min) 0 => 10 min SOLSUB Solution subinterval SOLMIN Min solution interval APARM General parameters 1=min. no. antennas 2 > 0 => data divided 3 > 0 => avg. RR,LL 4 > 0 => avg. freq. in IFs 5 = 1 => combine all IFs = 2 => also MB delay = 3 => combine IFs in halves = 4 => combine IFs in thirds = N => combines IFs in N-1 pieces SEE HELP WARNING 6=print level, 1=some 7=SNR cutoff (0=>5) 8=max. ant. # (no AN) 9 > 0 => do exhaustive baseline search 10 > 0 -> fit dispersion and IF group delay after fit of SB delays DPARM Delay-rate parameters 1=no. bl combo. (def=3) 2=delay win (nsec), if <0 no delay search done 3=rate win (mHz) 4=int. time (sec) 0 => min. found in data 5 >0 => don't do ls. soln 6 >0 => don't avg. in freq 7 >0 => don't rereference phase 8 > 0 => activate zero'ing options 9 > 0 => do not fit rate ANTWT Ant. weights (0=>1.0) BIF First IF included when APARM(5) > 0 EIF Last IF included when APARM(5) > 0 BPARM Task enrichment parameters (1) Antenna diameter (m) 0 -> no correction (2) Omit CC options (3) spectral index radius 0 -> no correction FQTOL Frequency tolerance in kHz (primary beam & spec index) IN3NAME Spectral index image name IN3CLASS Spectral index image class IN3SEQ Spectral index image sequence number IN3DISK Spectral index image disk IN4NAME Spectral curvature name IN4CLASS Spectral curvature class IN4SEQ Spectral curvature sequence number IN4DISK Spectral curvature disk BADDISK 0.0 15.0 Disk no. not to use for scratch files. ---------------------------------------------------------------- IMFRING Task: IMFRING is a procedure that combines IM2CC, OOSUB, FRING, and finally TACOP. IM2CC breaks a large (usually CASA) image into pieces, making both an image and a Clean components table for each piece. This is needed to allow AIPS to use its geometries while CASA has used the W-projection geometry. OOSUB divides the data for a calibration source by the model from these pieces plus options to permit frequency-dependent primary beam and spectral index corrections. CALIB then determines an IF-dependent delay and phase, using the divided data. A solution (SN) table is written and copied to the input uv file by TACOP. Finally the temporary, divided data set is deleted (optionally) and the image pieces are deleted.. This procedure does not apply data selection and calibration adverbs to the input data set. You must apply these with SPLIT or SPLAT (or other tasks) to make a data set consisting solely of the edited/calibrated data that you wish to self-cal. IMFRING makes a number of temporary files all of which are assigned specific names including sequence number 1. It will check for the presence of any of these on your disks before doing work. If any are present, IMSCAL will list them and quit, allowing you to rename them or delete them. This procedure is obtained by entering RUN OOCAL. Adverbs: INNAME.....Input UV file name (name). Standard defaults. INCLASS....Input UV file name (class). Standard defaults. INSEQ......Input UV file name (seq. #). 0 -> highest. INDISK.....Disk drive # of input UV file. 0 -> any. **** Model image in Jy/pixel (not convolved with beam) **** IN2NAME....Input image file name (name). Standard defaults. IN2CLASS...Input image file name (class). Standard defaults. IN2SEQ.....Input image file name (seq. #). 0 -> highest. IN2DISK....Disk drive # of input image. 0 -> any. BLC........The bottom left-hand pixel of the input image which becomes the bottom left corner of the subimage from which the NX x NY panels are taken. 0 -> 1. TRC........The top right-hand pixel of the input image which becomes the top right corner of the subimage from which the panels are taken. 0 -> max allowed value. ICUT.......CC components are made only from pixel values greater in absolute value than ICUT and FLUX.......CC components are made only from pixel values greater than FLUX (in actual value). Thus FLUX=0 cuts off all negatives. NX.........The X axis is divided into NX nearly equal panels. NY.........The Y axis is divided in NY nearly equal panels. Be sure to make enough to account for any W term issues. OUTNAME....The output subimages are stored on OUTDISK with this name parameter. The OUTSEQ=1 and OUTCLASS=IMCnnn. The output from the OOSUB step in OOCAL also uses this name with OUTCLASS 'OOCAL1'. OUTDISK....The output subimages and CC files are put on OUTDISK, the OOSUB output file is put on INDISK. It is better to avoid Lustre disks for the CC files. DOKEEP.....> 0 => keep the file produced by OOSUB containing the input data divided by the model and the SN table produced by CALIB <=0 => delete this temporary file after TACOP. BCHAN......First channel to use. 0=>all. ECHAN......Highest channel to use. 0=>all higher than BCHAN ANTENNAS...A list of the antennas to have solutions determined. If any number is negative then all antennas listed are NOT to be used to determine solutions and all others are. All 0 => use all. DOFIT......A list of the antennas for which solutions should or should not be determined. If DOFIT = 0, all antennas are solved for. If any entry <= -1, , then DOFIT is taken as the list of antennas for which no solution is desired; a solution is found for all antennas not in DOFIT. If any entry of DOFIT is non-zero and all are >= 0, then only those antennas listed in DOFIT will be solved for - all other selected antennas will not be solved for. NOTE: THIS OPTION MUST NOT BE USED UNLESS YOU UNDERSTAND IT FULLY. Basically, it should be used to solve for the gains of "poor" antennas after the "good" antennas have been fully calibrated. Antennas included in ANTENNAS but not in DOFIT are assumed to have a complex gain/delay/rate of (1,0,0,0) and the gains/delays produced will be very wrong if this is not the case. See HELP DOFIT. The following may be used for all data files (except as noted): UVRANGE....The range of uv distance from the origin in kilowavelengths over which the data will have full weight; outside of this annulus in the uv plane the data will be down weighted by a factor of WTUV. WTUV.......The weighting factor for data outside of the uv range defined by UVRANGE. 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 ONEFREQ....In IMAGR, a CC file is made from the "average" of all channels included in the bandwidth synthesis. But it is also possible to make the model image(s) from a single frequency (or from frequencies within FQTOL anyway). Set ONEFREQ = 1 if the model was made this way, leave it zero if all frequencies were included in the model. 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 The following control how the solutions are done, if you don't understand what a parameter means leave it 0 and you will probably get what you want. REFANT.....The desired reference antenna for phases. SEARCH.....List of Prioritized antennas to be used when APARM(9)>0. This adverb supplements REFANT. Along with APARM(9)>0, it is recommended that SEARCH be filled with a list of antennas whose order reflects the user's notion of which baselines will be easiest to find fringes on. All baselines to each antenna in SEARCH will be searched in order looking for fringes. All remaining baselines will then be searched. Choosing SEARCH wisely will speed the FFT portion of FRING. The antenna chosen in REFANT is treated as SEARCH(0), ie all baselines to it are searched first. SOLINT.....The solution interval (min.) You really should set this; longer values are allowed beginning with 15OCT96. 0 => 10 minutes for all inputs If SOLINT > Scan/2 (in Multisource) SOLINT = Scan. SOLSUB.....The begin time for the next interval in advanced from the current one by SOLINT / SOLSUB where 1 <= SOLSUB <= 10. 0 -> 1. This is to produce solutions at sub-intervals of SOLINT based on SOLINT length of averaging. SOLMIN.....Minimum number of subintervals to be used in a solution. 0 -> SOLSUB. APARM......General control parameters. APARM(1)...Minimum number of antennas allowed for a solution. 0 => 3. APARM(2)...If > 0 then the input data has already been divided by a model; only solutions will be determined. APARM(3)...If > 0 then average RR, LL APARM(4)...If > 0 average all frequencies in each IF before the solution and in the output for single source files. APARM(5)...WARNING: IF THE FREQUENCY INCREMENT BETWEEN IFS THAT WILL BE INCLUDED IN A GROUP HAS THE OPPOSITE SIGN FROM THE FREQUENCY INCREMENT BETWEEN CHANNELS IN THE IFS OF THAT GROUP, YOU SHOULD NOT USE THE FOLLOWING (SET APARM(5)=0 ONLY). If = 1 then make a combined solution for the IFs; If <= 0 then make separate solutions. If = 2 do separate least squares fits for single- and multi-band delays. This option will override APARM(4) > 0. WARNING: multi-band delays derived by this method cannot be smoothed. If = 3 then make solutions combining IFs 1 through NIF/2 and IFs NIF/2+1 through NIF. This may be appropriate for the EVLA in which the first NIF/2 are from hardware IF AC and the others are from hardware BD. If = 4 then make solutions combining IFs 1 through NIF/4, NIF/4+1 through NIF/2, NIF/2+1 through 3*(NIF/4), and IFs 3*(NIF/4)+1 through NIF. This may be appropriate for the EVLA for 3-bit sampling in which each quarter passes through separate hardware and hence has separate delay errors. NOTE - APARM(10) can partly override this - causing the task to fit a delay in each IF and then to fit a dispersion across all IFs plus delay for each group of IFs. The output SN table will contain dispersion values plus the single-band delays and phases corrected for the dispersion. APARM(6)...Print flag, -1=none, 0=time every 10th time, 1=time,some info, 2=more including the antenna signal to noise ratio, 3=a very great deal. APARM(7)...The minimum allowed signal-to-noise ratio. 0 => 5 APARM(8)...If there is no antenna (AN) table with the input file then the maximum antenna number in the file should be entered in APARM(8). APARM(9)...If > 0, perform exhaustive baseline search in the initial FFT stage. Normally, the first stage of FRING is to FFT individual baselines searching for initial estimates of the residual phases, rates, and delays. This stage is notable in that FRING gives up too easily - only baselines to the user-selected REFANT and one other antenna are searched. APARM(9)>0 instructs FRING to exhaustively search for initial estimates for each antenna's errors. See SEARCH above as well. APARM(10)..If > 0, causes the task to fit a delay in each IF and then to fit a dispersion plus a delay for each group of IFs to the SB delays in all IFs. The output SN table will contain dispersion values plus the single-band delays and phases corrected for the dispersion. Delay-rate control parameters: DPARM......Delay rate parameters. DPARM(1)...Number of baseline combinations to use in the initial, coarse fringe search (1-3). Larger values increase the point source sensitivity but reduce the sensitivity to extended sources when an accurate model is not available. 0=>3. DPARM(2)...The delay window to search (nsec) centered on 0 delay. 0 => full Nyquist range defined by the frequency spacing. If DPARM(2) < 0.0 no delay search will be performed. DPARM(3)...The rate window to search (mHz) centered on 0 rate. 0 => full Nyquist range defined by the integration time. DPARM(4)...The minimum integration time of the data (sec); 0 => search the data to find the minimum integration time. The correct minimum of all baselines should be supplied. DPARM(5)...If > 0 then don't do the least squares solution. If the least squares solution is not done then only the coarse search is done and much less accurate solutions are obtained. DPARM(6)...If > 0 then the output data will not be averaged in frequency else, all frequencies in each IF will be averaged. Affects single source files only. DPARM(7)...If > 0 then the phase, rate and delays will not be re-referenced to a common antenna. This option is only desirable for VLBI polarization data. DPARM(8)...DPARM(8)>0 allows zero'ing of RATE, DELAY, and/or PHASE solutions. ** Note that the ZEROing is done _AFTER_ the FRING solution is found, this is not the mechanism for turning off the DELAY, RATE, or PHASE search, see DPARM(2-3) for that capability. ** DPARM(8) value zero RATES? zero DELAYs? zero PHASEs? 0 No No No 1 Yes No No 2 No Yes No 3 Yes Yes No 4 No No Yes 5 Yes No Yes 6 No Yes Yes 7 Yes Yes Yes DPARM(9)...> 0 => supress fitting for rate (rather than just zero the fit afterwards). This assumes that the true rate is small and causes all the data in SOLINT to be averaged before being fed to the fitter. DPARM(8)=1 is not needed in this case. 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 numbers correspond to which antennas. BIF........First IF included when APARM(5)=1,3,4 (all IFs receive the solution found for the appropriate group of IFs, but only BIF-EIF are used to find it). EIF........Last IF included when APARM(5)=1,3,4 (all IFs receive the solution found for the appropriate group of IFs, but only BIF-EIF are used to find it). BPARM......Correction control parameters (SEE EXPLAIN IMAGR): (1) If > 0 then make frequency dependent primary beam corrections assuming an antenna diameter of IMAGRPRM(1) meters. Note that VLA and ATCA arrays (TELESCOPE header parameter) use the default primary beam parameters defined elsewhere in AIPS, while other antennas actually use IMAGRPRM(1) as the diameter of a "standard" telescope. See FQTOL below also. (2) If BPARM(1) > 0, you may omit selected CCs from the operation based on position: BPARM(2) <= 0 : Include all CCs = 1 : Omit CCs within the main beam at all frequencies = 2 : Omit CCs within the main beam at some frequncies = 3 : Omit Ccs outside the main beam at some frequencies = 4 : Omit CCs outside the main beam at all frequencies (3) 1 => use a spectral-index image represented in IN3NAME, IN3CLASS, IN3SEQ, IN3DISK below to correct the Clean component model for each channel. IN4NAME et al will also be used as a curvature image iff IN3NAME are specified. BPARM(3)-0.5 is used as a radius in pixels over which the spectral index image is averaged. When it is small (0 < BPARM(3) <~ 1), the spectral index is interpolated rather than averaged. See FQTOL below as well. When doing spectral index, the primary beam correction (BPARM(1)) costs very little extra. This parameter is IMAGRPRM(17) in IMAGR. FQTOL......Frequency tolerance in kHz. Spectral channels with FQTOL are handled together (use the same average CC model) when applying the primary beam and spectral index corrections. Default is to do each channel separately which can take a long time. IN3NAME....Image name of spectral index image; no default. IN3CLASS...Image class of spectral index image; no default. IN3SEQ.....Image sequence of spectral index image; 0 -> highest. IN3DISK....Disk of spectral image image; 0 -> any. IN4NAME....Image name of spectral index curvature image; no default. Curvature images should be base 10 rather than base e - they differ by a factor of 2.3. Also the reference frequency is 1.0 GHz. These are changes done 2010-07-13. IN4CLASS...Image class of spectral index curvature image; no default. IN4SEQ.....Image sequence of spectral index curvature image; 0 -> highest. IN4DISK....Disk of spectral curvature image image; 0 -> any. BADDISK....A list of disk numbers to be avoided when creating scratch files. ----------------------------------------------------------------