[daip] CLCOR bug?

[Leonia Kogan]

I think this is a problem of accuracy of the source recalculation by 
the subroutine JPRECS.

I'll look at that

Leonia
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>From owner-daip at kochab.cv.nrao.edu Thu Jun 28 11:29 MDT 2001
X-Mailer: exmh version 2.1.1 10/15/1999
To: daip at zia.aoc.NRAO.EDU
Subject: [daip] CLCOR bug?
Mime-Version: 1.0
Date: Thu, 28 Jun 2001 11:29:32 -0600
From: Amy Mioduszewski <amiodusz at aoc.nrao.edu>
Sender: owner-daip at kochab.cv.nrao.edu
Precedence: bulk
X-Lines: 121
Status: RO

I am trying to correct a position of a source in an experiment of
mine with CLCOR.  I then subtracted the correction and the RAAPP and
DECAPP in the SU table where what they were originally but the RAEPO
and the DECEPO where different.  Here are the inputs for CLCOR (I am
doing this for a rather larger shift than I really want so you can
actually see the sift with the limited significant digits that PRTAB
shows):

AIPS 2: CLCOR     Task which applies various corrections to CL tables.
AIPS 2: Adverbs     Values                 Comments
AIPS 2: ----------------------------------------------------------------
AIPS 2: INNAME     'BR058B 18CM '          Input UV file name (name)
AIPS 2: INCLASS    'CLCOR '                Input UV file name (class)
AIPS 2: INSEQ         1                    Input UV file name (seq. #)
AIPS 2: INDISK        2                    Input UV file disk unit #
AIPS 2: SOURCES    'J0422+5324      '      Source list ' '=>all.
AIPS 2:            *rest ' '
AIPS 2: STOKES     '    '                  Stokes type to process
AIPS 2: SELBAND      -1                    Bandwidth to select (kHz)
AIPS 2: SELFREQ      -1                    Frequency to select (MHz)
AIPS 2: FREQID        1                    Freq. ID to select, 0=>all
AIPS 2: BIF           0                    Lowest IF number 0=>all
AIPS 2: EIF           0                    Highest IF number 0=>all
AIPS 2: TIMERANG   *all 0                  Time range to use.
AIPS 2: ANTENNAS   *all 0                  Antennas to correct.
AIPS 2: SUBARRAY      0                    Subarray;  0 => 1.
AIPS 2: GAINVER      16                    CL table version to update
AIPS 2: OPCODE     'ANTP'                  Operation code.
AIPS 2: CLCORPRM      0           0        Parameters (see HELP CLCOR).
AIPS 2:               0           0           0.36        0.18
AIPS 2:            *rest 0
AIPS 2: BADDISK    *all 0                  Disks to aviod for scratch
 

Prior to the correction using PRTAB to print the interesting columns:

BR058B 18CM .CLCOR .   1  Disk= 2    SU Table version   1
Title: AIPS UV DATA FILE SOURCE TABLE
Created by      UVCOP on 24-APR-2001 12:44:11
Last written by UVCOP on 28-JUN-2001 10:44:00
Ncol  19  Nrow       3    Sort cols:
    Table has     4 keyword-value pairs:
   NO_IF    =            4
   VELTYP   =  GEOCENTR
   VELDEF   =  OPTICAL
   FREQID   =            1
   Table format incompatable with FITS ASCII tables

COL. NO.         2             11              12              14              
15
     ROW    SOURCE        RAEPO           DECEPO          RAAPP           
DECAPP
  NUMBER                  DEGREES         DEGREES         DEGREES         
DEGREES
       1    J0419+5722    6.483089E+01    5.738333E+01    6.478838E+01    
5.737507E+01
       2    CICAM         6.492557E+01    5.599936E+01    6.488398E+01    
5.599116E+01
       3    J0422+5324    6.568500E+01    5.340729E+01    6.564481E+01    
5.339930E+01

After running CLCOR I get this from PRTAB

BR058B 18CM .CLCOR .   1  Disk= 2    SU Table version   1
Title: AIPS UV DATA FILE SOURCE TABLE
Created by      UVCOP on 24-APR-2001 12:44:11
Last written by CLCOR on 28-JUN-2001 10:51:05
Ncol  19  Nrow       3    Sort cols:
    Table has     4 keyword-value pairs:
   NO_IF    =            4
   VELTYP   =  GEOCENTR
   VELDEF   =  OPTICAL 
   FREQID   =            1
   Table format incompatable with FITS ASCII tables

COL. NO.         2             11              12              14              
15
     ROW    SOURCE        RAEPO           DECEPO          RAAPP           
DECAPP
  NUMBER                  DEGREES         DEGREES         DEGREES         
DEGREES
       1    J0419+5722    6.483089E+01    5.738333E+01    6.478838E+01    
5.737507E+01
       2    CICAM         6.492557E+01    5.599936E+01    6.488398E+01    
5.599116E+01
       3    J0422+5324    6.568531E+01    5.340730E+01    6.564498E+01    
5.339935E+01

After running with CLCORPRM 0 0 0 0 -0.36 -0.18:

BR058B 18CM .CLCOR .   1  Disk= 2    SU Table version   1
Title: AIPS UV DATA FILE SOURCE TABLE
Created by      UVCOP on 24-APR-2001 12:44:11
Last written by CLCOR on 28-JUN-2001 10:56:33
Ncol  19  Nrow       3    Sort cols:
    Table has     4 keyword-value pairs:
   NO_IF    =            4
   VELTYP   =  GEOCENTR
   VELDEF   =  OPTICAL
   FREQID   =            1
   Table format incompatable with FITS ASCII tables

COL. NO.         2             11              12              14              
15
     ROW    SOURCE        RAEPO           DECEPO          RAAPP           
DECAPP
  NUMBER                  DEGREES         DEGREES         DEGREES         
DEGREES
       1    J0419+5722    6.483089E+01    5.738333E+01    6.478838E+01    
5.737507E+01
       2    CICAM         6.492557E+01    5.599936E+01    6.488398E+01    
5.599116E+01
       3    J0422+5324    6.568514E+01    5.340725E+01    6.564481E+01    
5.339930E+01

As you can see the RAAPP and DECAPP are the same as before the first PRTAB 
output but
RAEPO and DECEPO are are different and the difference is big at VLBA scales.

Amy



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