; TYAPL ;--------------------------------------------------------------- ;! undoes and re-does nominal sensitivity application ;# Task Calibration VLA ;----------------------------------------------------------------------- ;; Copyright (C) 2007-2017 ;; 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 ;----------------------------------------------------------------------- TYAPL LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC TYAPL Undoes and re-does nominal sensitivity application 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 # FREQID 0.0 Frequency ID number: 0 -> 1 SUBARRAY 0.0 Subarray: 0 -> 1 FLAGVER -1.0 > 0 => apply flags to output data and TY/SY/SN tables DOFLAG = 1,3 -> do NOT flag TY/SY = 2,3 -> do NOT flag SN INEXT TY or SY for VLA or EVLA INVERS Input ?Y table undo 0=>none IN2VERS Input ?Y table redo 0=>none OUTNAME Output UV file name (name) OUTCLASS Output UV file name (class) OUTSEQ Output UV file name (seq #) OUTDISK Output UV file disk unit OPTYPE 'PGN' use SY post gain only 'CL' write CL table =bad idea 'CLP' write CL post gain only REWEIGHT Additional SY scaling factors for visibilities, weights DOWEIGHT -1.0 1.0 < 0 => do NOT compute weights from SY values NOTE: 0 means do weights CUTOFF 0.0 1.0 > 0 => if fraction of good SY values < CUTOFF, apply an average correction instead FQCENTER >= 0 -> center frequency axis CALIN Antenna efficiencies file ---------------------------------------------------------------- TYAPL Task: For the EVLA, the SysPower table in the SDM records the switched power when the noise tube is on and the switched power when the noise tube is off. If the AIPS files are obtained via OBIT --- AIPS "verb" BDF2AIPS --- then an SY table is available. It may be applied to adjust the gains and the data weights. If one has been applied, the application may be removed and a new SY table (i.e. one clipped and smoothed by TYSMO) may be applied. This is much like the Tsys application done formerly for the VLA but there are differences. For details, see EVLA Memo 145 by Rick Perley (May 2010). TYSMO, SNEDT, EDITA, and SNPLT all understand SY tables and allow you to manipulate and/or view them. The task uses the input INTTIM random parameter where available as the integration time and, if unavailable, assumes that the input weights are equal the integration time. If you have done frequency averaging, this will not be true and the weights will be incorrect after TYAPL (if INTTIM is missing). Do not use TYAPL if your data includes observations of the Sun. Use appropriate tasks instead: SOLCL for VLA data and SYSOL for EVLA data. Note that TYAPL with SY tables requires valid values for Pdif, Psum, and the post-detector gains. If you have flagged data in the SY table, TYAPL will flag the corresponding visibilities. TYSMO allows you to replace flagged samples in the SY table with averages from nearby samples. You should consider doing this with all 3 data types before running TYAPL unlesss you want the data to be flagged. TYAPL now has the ability to apply a flag table to the data as they are read. Like UVCOP, up to 600001 flags are allowed to apply to a single time. This ability was added so that you can use the required data copy in TYAPL instead of an additional data copy in UVCOP to reduce the size of the data and dispense with large flag tables generated by auto-flag tasks like RFLAG. Note that TYAPL should copy the data set for 3 reasons: 1. The system gains may do abrupt jumps usually at the original scan boundaries but sometimes at other times. A CL table could handle these jumps if it was structured to match the original scans, but that original structure is often lost. 2. The data weights after TYAPL need to have the amplitude gains applied to them as well as the visibilities since any amplitude gains at that point should only reflect errors in the assumed Tcal's. However, it is completely incorrect to apply the amplitude gain from the SY table to the weights computed from the SY table. The CL tables contain a cumulative amplitude gain and there is no reasonable way to differentiate the SY table gains from the other gains later in the processing. 3. New weights are needed and TYAPL computes remarkably good ones. This means the data set must be rewritten to supply those weights and it is completely unsafe to overwrite the input data set. For the VLA, Tsys is the nominal sensitivity and Tant is some form of system temperature. FILLM, by default, scales the measured correlation coefficients by the instantaneous measured nominal sensitivities, producing data approximately in deci-Jy. FILLM can be told to load correlation coefficients only. For calibration purposes, it is best to have the nominal sensitivites applied, but it may be better to use a clipped and time-smoothed version of those sensitivities. TYSMO allows you to do that clipping and smoothing or, if you prefer interactive tasks, try SNEDT. Then one can remove the nominal sensitivities applied by FILLM, if any, and apply smoothed nominal sensitivites (or leave the data as correlation coefficients if desired) with TYAPL. VLBI users warning: This task is not elaborately intelligent about looking through the TY table to match up Tsys measurements by source and time. It is tested for and assumes the simple, all antennas at the same time and source form for the TY tables of the VLA. 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. FREQID.....Frequency ID number to do 0 => 1 SUBARRY....Subarray to do 0 => 1 FLAGVER....If > 0, apply the specified flag table version to the data and do not copy it to the output. Unlike regular calibration routines (but like UVCOP), FLAGVER = 0 means no flagging. The flag table is applied to any TY, SY, and SN tables as they are copied (spectral-channel independent flags only). DOFLAG.....Controls whether FLAGVER is applied to tables or not. = 0 => apply FLAGVER (if > 0). If 1 => do not flag SY and TY tables, =2 => do not flag SN tables, =3 => do NOT flag SN, SY, or TY tables. INEXT......Input extension type: 'SY' for SysPower tables from the VLA, 'TY' for System Temperature tables from the (old) VLA. ' ' takes whichever one it finds. INVERS.....Input version number of the TY table which was applied to the data and is to be unapplied. 0 => none If input file is in correlation coefficient form, it is an error to set INVERS > 0. IN2VERS....Input version number of the ?Y table that is to be applied after INVERS is undone. 0 => none If the data are not in correlation coefficient form on input or after INVERS is undone, then it is an error to set IN2VERS > 0. If INVERS <= 0 and IN2VERS <= 0, then the program will set IN2VERS to max ?Y version if the data are correlation coefficients and INVERS to max ?Y version if the data are in visibility form, leaving the other at 0. OUTNAME....Output UV file name (name). Standard defaults. OUTCLASS...Output UV file name (class). Standard defaults. OUTSEQ.....Output UV file name (seq #). 0 => highest unique OUTDISK....Output UV file disk unit. 0 => highest w space. OPTYPE.....'PGN' use the SY table post-gain only to adjust gains The following are a bad idea for reasons given above: 'CL' apply the TY or SY gains to the highest CL table version and write a new CL table 'CLP' write the SY table post gain into a new CL table In the case of the above three OPTYPEs, DOWEIGHT is set to -1. If you do the CL operation, you must compute weights with REWAY and only with DOCAL true. Any other value of OPTYPE does the normal operations with Pdif and Psum from the SY table and will write a new data set with weights controlled by the user-chose value of DOWEIGHT. REWEIGHT...Scale the visibilites by REWEIGHT(1) and the weights by REWEIGHT(2). This option is allowed for now on SY tables only since the correct scaling is uncertain. 0 -> 1 DOWEIGHT...>= 0 => compute weights from SY values, < 0 do not change input weights. NOTE the non-standard use of the logical in which 0 is true. If OPTYPE = 'PGN', 'CL', or 'CLP', DOWEIGHT is set to false. CUTOFF.....<= 0 => data for which there is not a valid SY table value are flagged. > 0 => The SY table is examined in advance. If the fraction of valid SY table entries for a particular polarization, IF, and antenna is less than CUTOFF, the gain and weight factors for that antenna, IF, and polarization will be taken to be the average of those parameters for the antennas that are not "skipped". The data are not flagged. FQCENTER,..> 0 => Change frequency axis reference pixel to Nchan / 2 + 1 else => do not change reference pixel CALIN......The name of a text file to provide antenna efficiencies as a function of antenna, frequency, and polarization. By default, the system file is called: 'AIPSIONS:VLA.EFFICIENCIES' If it is missing, a small table which is antenna and polarization independent is used instead. ----------------------------------------------------------------