[daip] offset calibrator

[Geoffrey Bower]

Hi D-AIP,

I have what I think is a simple problem but I cannot find the solution for
it.  I have VLA multi-frequency continuum observations at 22 GHz.  The
calibrator is not at the phase center.  I self-calibrate using a model
image with the calibrator at its true location.  When I transfer these
solutions to the target sources, the phases are clearly scrambled and
the image is hash --- no source detected where I know one exists.  I have
also tried correcting the calibrator source position with CLCOR and then
imaging, also without success.

Any ideas about how to proceed?

Cheers,

Geoff


Details:
---------

AIPS version 31DEC03

calibrator is:

   1 SGRA            : 0000         17:45:42.0500 -29:00:10.120  176838

actual location of calibrator is:

				    17:45:40.038  -29:00:28.104

This includes ~1 Jy point source.

one of the target sources overlaps with Sgr A, thus should also include 1 Jy 
source (and does with self-cal on this source):

  79 17456-29002     : 0000         17:45:38.3492 -29:00:10.120    7150



AIPS 2: Image=MULTI     (UV)         Filename=20030803    .CH 0  .   1
AIPS 2: Telescope=VLA                Receiver=VLA
AIPS 2: Observer=AB1086              User #=  777
AIPS 2: Observ. date=03-AUG-2003     Map date=31-MAR-2004
AIPS 2: # visibilities   1250850     Sort order  TB
AIPS 2: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  BASELINE  TIME1
AIPS 2:            SOURCE  FREQSEL  WEIGHT  SCALE
AIPS 2: ----------------------------------------------------------------
AIPS 2: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
AIPS 2: COMPLEX      1   1.0000000E+00       1.00  1.0000000E+00    0.00
AIPS 2: FREQ         1   2.2485100E+10       1.00  1.5625000E+07    0.00
AIPS 2: STOKES       4  -1.0000000E+00       1.00 -1.0000000E+00    0.00
AIPS 2: IF           1   1.0000000E+00       1.00  1.0000000E+00    0.00
AIPS 2: RA           1    00 00 00.000       1.00       3600.000    0.00
AIPS 2: DEC          1    00 00 00.000       1.00       3600.000    0.00
AIPS 2: ----------------------------------------------------------------
AIPS 2: Coordinate equinox 2000.00
AIPS 2: Maximum version number of extension files of type HI is   1
AIPS 2: Maximum version number of extension files of type AN is   1
AIPS 2: Maximum version number of extension files of type NX is   1
AIPS 2: Maximum version number of extension files of type SU is   1
AIPS 2: Maximum version number of extension files of type FQ is   1
AIPS 2: Maximum version number of extension files of type CL is   3
AIPS 2: Maximum version number of extension files of type TY is   1
AIPS 2: Maximum version number of extension files of type WX is   1
AIPS 2: Maximum version number of extension files of type OF is   1
AIPS 2: Maximum version number of extension files of type SN is   2
AIPS 2: Keyword = 'OBSCHANS'  value =            8
AIPS 2: Keyword = 'CORRMODE'  value = 'PA      '
AIPS 2: Keyword = 'SELCHANS'  value =            7
AIPS 2: Keyword = 'VLAIFS  '  value = 'AC      '


-------------------------------------------------------------------------------
Geoffrey C. Bower 		gbower at astro.berkeley.edu 
601 Campbell Hall		Tel: +1 510 642 4075
Radio Astronomy Lab     	Fax: +1 510 642 3411
UC Berkeley             	Web: http://astro.berkeley.edu/~gbower
Berkeley CA 94720 USA
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