; CRSFRING ;--------------------------------------------------------------- ;# PROCEDURE VLBI ;! Procedure to calibrate cross pol. delay and phase offsets ;----------------------------------------------------------------------- ;; Copyright (C) 1995, 1996, 2002 ;; 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 ;----------------------------------------------------------------------- ;--------------------------------------------------------------- CRSFRING LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC CRSFRING: Procedure to calibrate cross pol. delays Use RUN CRSFRING first 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 # OUTDISK Disk for temporary files FLAGVER Flag table to use GAINUSE Calibration table to use NO DEFAULT SUBARRAY 0.0 99.0 Selected subarray ANTENNAS List of antennas, 0->use all REFANT Reference antenna CALSOUR Calibrator sources to use. See note in HELP file! TIMERANG Time range SOLINT Pre-averaging interval (min) BADDISK Disk drive #'s to avoid ---------------------------------------------------------------- CRSFRING Procedure: This procedure use a selected subset of a uv data set and determine cross polarized multi and single band delays. The average single band and multiband delays will be written into an SN table which can be applied to the GAINUSE CL table. See EXPLAIN CRSFRING for details. Before attempting to use CRSFRING the RUN file CRSFRING must be run to define the procedure. This is done by: >RUN CRSFRING and only needs be done once. CRSFRING creates one temporary file which it will destroy if able. The name of this files is fixed and it must be destroyed if a previous attempt at CRSFRING failed. To execute the procedure simple type: >CRSFRING 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. OUTDISK....Disk for temporary files 0->INDISK. FLAGVER....Flag table version to apply GAINUSE....CL table from prior calibration to apply before determining solutions. There is no default. SUBARRAY...Subarray to use. ANTENNAS...List of antennas, 0->use all. REFANT.....Reference antenna. Use the one you used for parallel hand fringe fitting. CALSOUR....Calibrator sources to use. NOTE! Selection of only ONE source is not implemented correctly -> use TIMERANG instead. TIMERANG...Timerange of the data subset. SOLINT.....The BLAVG pre-averaging interval (min) BADDISK...Disk drive #'s to avoid for scratch files ---------------------------------------------------------------- CRSFRING: Make an SN for the calibration of cross polarized delays. Documentor: K. J. Leppanen Related Programs: BLAVG, FRING, POLSN, CLCAL Calibration of cross polarized delays This procedure will take a selected subset of a uv data set and determine the corrections needed to remove differences in single and multiband delays for the right and left handed systems. The output is an SN table which can be applied to a CL table to affect these corrections. The output SN table will be written to the input data set and on successful completion of CRSFRING will be the highest version SN table. Cross polarized rate errors are assumed to be zero. It is assumed that parallel hand fringe fitting has been completed, and the resulting calibration is in the CL table version GAINUSE. The basic steps of this procedure are the following: 1) Average cross-polarized data from the selected timerange and antennas over baselines using the task BLAVG. This will improve the signal-to-noise ratio of the usually weak cross-polarized signal significantly. In most cases a single scan using all antennas is adequate, and can be selected by using the TIMERANGE adverb; the delay offsets should remain constant over the experiment. 2) Run FRING on this segment of data to obtain the delay and phase offsets, one solution per scan. Use APARM=2,0; DPARM=1,0,0,60*SOLINT, 0,0,1. Other FRING parameters are as passed to the procedure either explicitly in the inputs file or implicitly by the appropriate adverb values. 3) Run POLSN on the SN table produced by FRING. 4) Use TACOP to copy the SN table produced by POLSN to the original data set. When applying the SN table to the prior CL table with CLCAL use TIMER=0, ANTENNA=0, SOURC '', CALSOU '', and typically INTERPOL=''.