[daip] [!12546]: AIPS - Don't understand CLCAL interpolation

Wed Aug 8 15:45:22 EDT 2018

Michael Bietenholz updated #12546
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Don't understand CLCAL interpolation
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           Ticket ID: 12546
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/12546
                Name: Michael Bietenholz
       Email address: mbieten at yorku.ca
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template group: Default
             Created: 08 August 2018 07:45 PM
             Updated: 08 August 2018 07:45 PM
           Reply due: 10 August 2018 07:45 PM (2d 0h 0m)
      Resolution due: 04 May 2021 12:00 AM (999d 4h 15m)

I have a SN table with calibrator source entries at start & end.  I ran CLCAL to calibrate the intervening program source entries  using '2PT','FULL' and largely defaults otherwise (complete inputs below).  I expect that it would interpolate rate linearly, so the phase-vs-time slope should be changing linearly during the interpolated period.   As a test I used GAINV=1, which is an INDXR-generated CL table with all 0 phases & rates, and GAINU=9 - make a new CL table.   I attach CLCAL_phase.png which shows the resulting CL-table phase vs time, showing a phase-vs-time slope that changes non-linearly with time - contrary to my expectations.    The CL rates do behave the way I expect, ie. linearly interpolated between values at start and end. CL1 is plotted in yellow and CL9 in green.Another thing - possibly connected was this:  I ran CLCAL with CALSOURC=[calibrator=NRAO530], SOURCE=[program=SGRA],  OPCO='CALP'.  Since I'm only asking it to calibrate the SGRA entries, I expect that the NRAO530 (and other calibrator) entries in the CL table will remain unchanged.  This is not what happens (there are several calibrator sources, they are the  one shorter scans at the start and the three at the end) - which all seem to bet modified.Am I confused or is something funny going on here?Complete CLCAL inputs; I attach a tasav with the relevant tables in; 31DEC18 AIPS, midnight job yesterday.AIPS 1: CLCAL Task to manage SN and CL calibration tablesAIPS 1: Adverbs Values CommentsAIPS 1: ----------------------------------------------------------------AIPS 1: INNAME 'BY144C' Input UV file name (name)AIPS 1: INCLASS 'TASAV' Input UV file name (class)AIPS 1: INSEQ 2 Input UV file name (seq. #)AIPS 1: INDISK 5 Input UV file disk unit #AIPS 1: SOURCES 'SGRA' Source list to calibrateAIPS 1: *rest ' 'AIPS 1: SOUCODE ' ' Source "Cal codes"AIPS 1: CALSOUR 'NRAO530' Cal sources for calibrationAIPS 1: *rest ' 'AIPS 1: QUAL -1 Source qualifier -1=>allAIPS 1: CALCODE ' ' Calibrator code ' '=>allAIPS 1: TIMERANG *all 0 Time range to calibrateAIPS 1: SUBARRAY 0 Subarray, 0=>all,AIPS 1: ANTENNAS *all 0 Antennas selected, 0=> allAIPS 1: SELBAND -1 Bandwidth to select (kHz)AIPS 1: SELFREQ -1 Frequency to select (MHz)AIPS 1: FREQID -1 Freq. ID to select.AIPS 1: OPCODE ' ' Operation 'MERG','CALI',AIPS 1: 'CALP'; ' ' => 'CALP' ****AIPS 1: INTERPOL ' ' Interpolation function,AIPS 1: choices are: '2PT','SIMP',AIPS 1: 'AMBG','CUBE','SELF','POLY',AIPS 1: 'SELN'; see HELP for detailsAIPS 1: CUTOFF 0 Interpolation limit inAIPS 1: time (min); 0=> no limit.AIPS 1: SAMPTYPE ' ' Smoothing functionAIPS 1: BPARM *all 0 Smoothing parametersAIPS 1: ICUT 0.1 Cutoff for functional formsAIPS 1: DOBLANK 0 Blanked value interpolationAIPS 1: DOBTWEEN 1 > 0 -> smooth all sourcesAIPS 1: together; else separate themAIPS 1: SMOTYPE ' ' Data to smoothAIPS 1: SNVER 8 Input SN table, 0=>all.AIPS 1: INVERS 1 Upper SN table vers in aAIPS 1: range. 0=>SNVERAIPS 1: GAINVER 1 Input Cal table 0=>highAIPS 1: GAINUSE 9 Output CAL table 0=>high+1AIPS 1: REFANT 7 Reference antenna 0=>pick.AIPS 1: BADDISK *all 0 Disks to avoid for scratch

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