; FIXAL ;--------------------------------------------------------------- ;! least squares fit aliasing function and remove ;# TASK UV SPECTRAL VLA ;----------------------------------------------------------------------- ;; Copyright (C) 2008 ;; 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 ;----------------------------------------------------------------------- FIXAL LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC FIXAL Least squares fit aliasing function and remove 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 # SOURCES Source names for line sources NO '-' usage CALSOUR Continuum source names FLAGVER Flag table version IN2NAME Input cal file name (name) IN2CLASS Input cal file name (class) IN2SEQ 0.0 9999.0 Input cal file name (seq #) IN2DISK 0.0 9.0 Input cal file disk unit # BDROP 1.0 512.0 start chan in cal for cont EDROP 1.0 512.0 end chan in cal for cont OUTNAME Output UV file name (name) OUTCLASS Output UV file name (class) OUTSEQ -1.0 9999.0 Output UV file name (seq. #) OUTDISK 0.0 9.0 Output UV file disk unit #. BCHAN Lowest channel for cals ECHAN Highest channel for cals ICHANSEL Select channels to fit: NOTE this is start,end,increment and IF for each region DPARM -1.0 1.0 <=0 => average polarizations, IFs, times, antennas (5) > 0 keep imaginary (6) > Hanning smooth FLUX 0.0 Flag data if residual flux in any fit channel is > FLUX 0 -> 10**20 CUTOFF 0.0 Flag data if RMS of residual in fit channels > CUTOFF 0 -> 10**20 ---------------------------------------------------------------- FIXAL Task: EXPERIMENTAL TASK! This task does a special spectral fit designed to correct for aliasing of the continuum into the observing band caused only for EVLA-EVLA baselines when observed in the VLA-EVLA transition with the old correlator. The process which one must undertake to correct data affected by this problem is: 1. Flag EVLA-EVLA baselines in the FG table 2. Run BPASS on the VLA-VLA and VLA-EVLA baselines 3. Undo the EVLA-EVLA baseline flagging in the FG table 4. Run SPLAT to apply the BP table 5. Run UVAVG on one or more calibrator scans to make scan average data for the "cal" 6. Run FIXAL applying the cals of step 5. It reads in the data averaging each baseline.pol/IF separately. Sums up the cal channels BDROP through EDROP and divides the cal by this complex average. Then it fits the normalized cal to the channels of the input data to get the continuum flux and subtracts the channel-dependent part of that from the data. A procedure, FXALIAS, has been written to help implement this process. 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. SOURCES....Sources to be baselined using the specified ICHANSEL. ' '=> all except those in CALSOUR. The '-name' usage is not allowed here. CALSOUR....Sources to be baselined using BCHAN-ECHAN rather than ICHANSEL. ' ' => none. FLAGVER....specifies the version of the flagging table to be applied. 0 => highest numbered table. <0 => no flagging to be applied. IN2NAME....Input cal file name (name). Standard defaults. IN2CLASS...Input cal file name (class). Standard defaults. IN2SEQ.....Input cal file name (seq. #). 0 => highest. IN2DISK....Disk drive # of input cal file. 0 => any. BDROP......Begin channel for cal file unaffected by aliasing NO DEFAULT EDROP......End channel for cal file unaffected by aliasing NO DEFAULT 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....Disk drive # of output UV file. 0 => highest with space for the file. BCHAN......Lowest channel number in the input file to fit CALSOUR sources. 0=> Nchan/8 ECHAN......Highest channel number in the input file to fit CALSOUR sources. 0=> Nchan - Nchan/8 ICHANSEL...For sources named in SOURCES, selects up to 20 groups of channels/IF(s) to fit as sets of (Start,end,inc,IF), i.e., ICHANSEL = 6,37,1,0, 92,123,1,0 for two regions applying to all IFs. The first group for which ICHANSEL(2,i) <= 0 ends the list. Defaults: Any IF having no group assigned to it, gets a group including all channels. ICHANSEL(1,j) defaults to 1, 0 < ICHANSEL(2,j) < ICHANSEL(1,j) defaults to Nchan. ICHANSEL(3,j) < 1 or > ICHANSEL(2,j)-ICHANSEL(1,j)+1 defaults to 1. ICHANSEL(4) <= 0 => this group applies to all IFs. DPARM......(1) > 0 => do NOT average polarizations in fitting the aliasing function (2) > 0 => do NOT average IFs in fitting the aliasing function (3) > 0 => do NOT average times in fitting the aliasing function (4) > 0 => do NOT average antennas in fitting the aliasing function (5) > 0 => do full complex aliasing function < 0 => zero the imaginary part of aliasing function (6) > 0 => Hanning smooth the aliasing function FLUX.......If the residual flux in any channel used to fit the baseline exceeds FLUX, then the spectrum for that time, IF, and polarization is fully flagged. <= 0 => 1.0E20 CUTOFF.....If the RMS flux in the channels used to fit the baseline exceeds CUTOFF, then the spectrum for that time, IF, and polarization is fully flagged. <= 0 => 1.0E20 ----------------------------------------------------------------