; VLBAPCOR ;--------------------------------------------------------------- ;! Calculates and applies instrumental phase calibration ;# PROCEDURE VLBI UTILITY CALIBRATION ;----------------------------------------------------------------------- ;; Copyright (C) 2002, 2006, 2007, 2015 ;; 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 ;----------------------------------------------------------------------- ;--------------------------------------------------------------- VLBAPCOR LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC VLBAPCOR: Procedure to correct instrumental phases INNAME Input UV file name (name) INCLASS Input UV file name (class) INSEQ 0.0 9999.0 Input UV file name (seq. #) INDISK 0.0 9.0 Input UV file disk unit # TIMERANG Time range of a calibrator 1-4 = start day,hr,min,sec 5-8 = end day,hr,min,sec MUST BE SPECIFIED REFANT 0.0 20.0 Ref. antenna, 0=>the first SUBARRAY 0.0 9999.0 Subarray; 0 => all. CALSOUR Calibrator source name; blank => any GAINUSE CL table to use; 0=>highest ADVERBS FOR ANTENNAS NOT CONTAINED IN PC TABLE: INVER -1.0 46655.0 Input PC table, 0=>last one OPCODE 'CALP' if you are missing PC information for any antenna; otherwise ' ' ANTENNAS antennas for which manual phase corrections should be obtained (i.e. they are missing from the PC table or are the pcals in PC table are incorrect). ---------------------------------------------------------------- VLBAPCOR Type: Procedure Use: VLBAPCOR is a procedure that creates a CL table which corrects the instrumental phases and delays using the pulse-calibration information in the PC table and will run FRING for any antennas which are not in the PC table if instructed to do so. This should be run after VLBACALA (or VLBAPANG for polarization experiments) but before VLBAFRNG/VLBAKRNG. Type RUN VLBAUTIL to make the VLBAPCOR procedure available. 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. TIMERANG...Time range of the calibrator to be used. In order: Start day, hour, min. sec, End day, hour, min. sec. Days relative to reference date. MUST BE SPECIFIED. Pick a scan on a calibrator where all antennas are present and have strong fringes. REFANT.....Reference antenna, 0 => the first in the antenna list Set to a stable antenna that is preferably in the entire experiment SUBARRAY...The subarray to use. 0 => all CALSOUR....Calibrator source name. GAINUSE....Number of CL table with all calibration up to this point. 0 => highest OPCODE.....OPCODE in CLCAL; use 'CALP' if you have antennas with no entries in the PC table, otherwise use default. If OPCODE is set to 'CALP' and ANTENNAS are set then additional steps are added to the procedure to find the instrumental phase corrections for antennas that are not in PC table. If OPCODE='CALP but ANTENNAS are not set then the phase corrections are not solved for and the antennas which are not in the PC table will be uncorrected in the resulting CL table. See EXPLAIN file for a detailed explanation of how to deal with ANTENNAS which are not in the PC table after VLBAPCOR. ANTENNAS...Antennas that are not in the PC table, a manual instrumental phase correction will be found for these using FRING. This FRING will be run on the scan that is selected in TIMERANGE, therefore make sure that the segment of data in the TIMERANGE has strong fringes on all antennas that the instrumental phase correction is desired. OPCODE must be set to 'CALP' for this option. 0=> do not find manual phase correction using FRING ---------------------------------------------------------------- VLBAPCOR: Procedure to correct the instrumental phases using the pulse cals in the PC table. It can also finds the instrumental phases for antennas not in PC table using FRING. Documenter: Amy Mioduszewski Related Programs: VLBAUTIL, PCCOR, CLCAL, PCLOD, FRING, SNCOR This should be done after sampler corrections (VLBACCOR) and before the bandpass (VLBABPSS). After VLBAMPCL is run it is ESSENTIAL to check the solutions in POSSM setting GAINUSE to the CL table output by VLBAPCOR. VLBAPCOR assumes: 1. there is only one FREQID 2. that all IFs should be calibrated 3. that the highest PC table is the one to apply 4. MBDELY is not zero (see EXPLAIN PCCOR). If you want a manual instrumental phase correction on antennas that are not in the PC table (OPCODE='CALP' and ANTENNAS <> 0) then there are these additional assumptions: 5. that ANTENNAS have strong fringes on the input TIMERANGE 6. that the highest FG table is the one that should be applied Steps in VLBAPCOR: 1. Runs PCCOR, which takes the PC table with the highest # and calculates the instrumental phases and delays from the pulse- calibration tones. The TIMERANGE is needed to solve 2pi*N ambiguities but the solutions are calculated using the pulse-cal tones over all times. PCCOR produces a SN table. Output should be highest SN table. *2. Runs SNCOR twice, to zero the phases and delays (OPCODE= ZPHS, ZDEL' of the SN table created by PCCOR for the antennas in ANTENNAS if OPCODE='CALP'. 3. Runs CLCAL, with input OPCODE; ANTENNAS=0; INTERPOL=''; SNVER= SN table out of PCCOR; GAINVER = input GAINUSE; and GAINUSE= highest CL table +1. Output should be highest CL table. *4. Runs FRING, using the GAINUSE used in CLCAL in step 2. DPARM(8)=1 to zero rates. If FRING reports any "failed solutions" you MUST find another scan and run again, after you have deleted the SN and CL tables that VLBAPCOR has created. Unless there is a good reason for failed solutions, such as an entire IF has been flagged for a certain antenna. *5. Runs CLCAL with ANTENNAS equal to the input ANTENNAS GAINVER equal to input GAINUSE; SNVER equal to output SN table from FRING; GAINUSE equal to the CL table which is output in step 2; TIMERANGE =0; and CALSOUR = ''. *NOTE: Steps 2, 4 and 5 only take place if OPCODE='CALP' and ANTENNAS <> 0. If you want to do manual phase instrumental corrections for antennas missing from PC table after VLBAPCOR (there are many good reason to want to do this, such as wanting to use a different time range or KRING): 1. Make sure that OPCODE='CALP' when you run VLBAPCOR. 2. When you run FRING or KRING be sure: - to pick a TIMERANGE that has strong fringes on the antennas you wish to correct - the REFANT is the same as in VLBAPCOR - GAINUSE is equal to the CL table that is produced by VLBAPCOR, and DOCAL=2 - in FRING: DPARM(8)=1 in KRING: OPCODE='ZRAT' - ANTENNAS can be either the antennas you want to fit + REFANT or all the antennas - when you run FRING/KRING there are no failed solutions on the antennas you want to correct. 3. When you run CLCAL be sure: - ANTENNAS are ONLY the antennas you want to correct, do NOT put the REFANT in this list - REFANT is the same as in VLBAPCOR - SNVER is SN table out of FRING/KRING - GAINVER is the GAINUSE you used in VLBAPCOR, i.e. the CL table with all the calibration EXCEPT the instrumental phase corrections. - GAINUSE is the CL table output from VLBAPCOR (and that you used are GAINUSE in FRING/KRING). - TIMERANGE = 0 - CALSOUR = '' - OPCODE = 'CALI' For antennas that are present in the PC table but the pulse cals do not correct things satisfactorily: 1. Delete the CL table created by VLBAPCOR using EXTD and then do one of 2 things: 2. *EITHER* Run SNCOR twice: - set SNVER to the SN table created by VLBAPCOR - set ANTENNAS to the antennas that were not satisfactory - set OPCODE = 'ZPHS' - all other adverbs should be defaults - run SNCOR - set OPCODE = 'ZDEL' - run SNCOR Run CLCAL: - SNVER is SN table out of VLBAPCOR - GAINVER is the GAINUSE you used in VLBAPCOR, i.e. the CL table with all the calibration EXCEPT the instrumental phase corrections. - GAINUSE = highest CL table +1 - TIMERANGE = 0 - CALSOUR = '' - OPCODE = 'CALP' Then do steps 2 & 3 from the case where there are antennas missing from the PC table. *OR* Delete the SN table created by VLBAPCOR using EXTD and rerun VLBAPCOR with the 'bad' antennas in the ANTENNAS list. Then you are done.