[daip] something weird in CLCOR

[Leonia Kogan]

Claire,

CLCOR modifys the given (at SU table)apparent position of the source 
and then recalculates the new apparent positions to the epoch ones.

The apparent positions fill out the SU table by FITLD
The mistake of calculation of the aparent position was found in FITLD 
at the August of 2001. So if you loaded your data before the August of 2001 
your apparent postion s are  wrong (a little bit) and that is why you see
the difference in the epoch coordinates.

Leonia
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>From daip-admin at donar.cv.nrao.edu Mon Feb 11 10:49 MST 2002
From: Claire Chandler <cchandle at aoc.nrao.edu>
To: <daip at habanero.aoc.NRAO.EDU>
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Subject: [daip] something weird in CLCOR
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Date: Mon, 11 Feb 2002 10:48:38 -0700 (MST)
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Chaps,

When I try to apply a small position correction to data using CLCOR the
new position in the SU is not what I expect:

The original position in SU table is

   2 BNKL-I          : 0000         05:35:14.5098 -05:22:30.482  580562

CLCOR is run with the following inputs:

AIPS 1: Keyword = 'SOURNAM1'  value = 'BNKL-I  '
AIPS 1: Keyword = 'SOURNAM2'  value = '        '
>tget clcor
>inp
AIPS 1: CLCOR     Task which applies various corrections to CL tables.
AIPS 1: Adverbs     Values                 Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: INNAME     'BG118B      '          Input UV file name (name)
AIPS 1: INCLASS    'CVEL  '                Input UV file name (class)
AIPS 1: INSEQ         1                    Input UV file name (seq. #)
AIPS 1: INDISK        1                    Input UV file disk unit #
AIPS 1: SOURCES    'BNKL-I          '      Source list ' '=>all.
AIPS 1:            *rest ' '
AIPS 1: STOKES     '    '                  Stokes type to process
AIPS 1: SELBAND      -1                    Bandwidth to select (kHz)
AIPS 1: SELFREQ      -1                    Frequency to select (MHz)
AIPS 1: FREQID       -1                    Freq. ID to select, 0=>all
AIPS 1: BIF           0                    Lowest IF number 0=>all
AIPS 1: EIF           0                    Highest IF number 0=>all
AIPS 1: TIMERANG   *all 0                  Time range to use.
AIPS 1: ANTENNAS      1           2        Antennas to correct.
AIPS 1:               3           4           5           6
AIPS 1:               7           8           9          10
AIPS 1:              11        *rest 0
AIPS 1: SUBARRAY      0                    Subarray;  0 => 1.
AIPS 1: GAINVER       9                    CL table version to update
AIPS 1: OPCODE     'ANTP'                  Operation code.
AIPS 1: CLCORPRM      0           0        Parameters (see HELP CLCOR).
AIPS 1:               0           0           0.1         0.1
AIPS 1:            *rest 0
AIPS 1: BADDISK    *all 0                  Disks to aviod for scratch

and the output position in the SU table is:

   2 BNKL-I          : 0000         05:35:14.5041 -05:22:30.272  580562

when I'd have expected the declination to be more like -05:22:30.382.

Is this just a rounding error, or something more serious?

Claire

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