[daip] Re: CLCOR

[Chris Phillips]

Hi Leonia,

> CLCOR makes the correction of the apparent coordinates!!! of the source
> and the recalculates the new apparent position to the epoch position.

I don't really understand the meaning of the "!!!" here. I understand that
CLCAL changes the SU table, and I have a feeling it is doing it wrong
(though I may be missing some subtle point).

OK, I was previously looking at the source coordinates found through
LISTR. These do not seem to be the same as the EPOCH or APPARENT
positions in the SU table. The LISTR positions are surely important
because they end up being the coordinates of the centre of the map made by
IMAGR.

Anyhow what I have is:

"Observed" positions:

LISTR: 19:22:34.0631   15:30:15.582
SUEPO: 19:22:34.0560   15:30:15.5880
SUAPP: 19:22:35.8800   15:30:10.5840

The VLBA position of the source is 19:22:34.6992 15:30:10.032, so I ran
CLCOR with CLCORPRM 0 0 0 0 9.1943 -5.55

This then gives the positions of

LISTR: 19:22:34.7327   15:30:10.017
SUEPO: 19:22:34.7280   15:30:10.0080
SUAPP: 19:22:36.5040   15:30:05.0040

These have arcsec delta's of:

LISTR: 9.6785, -5.5650
SUEPO: 9.7132, -5.5800
SUAPP: 9.0195, -5.5800

To me this looks wrong.

> When your data were fitlded?

It was FITLDed a few months ago at Jodrell Bank. The data has been loaded
into aips and exported as FITS files a few times at different places. (Ie
originally done at Jodrell Bank. Then partially processed at JIVE, now at
ATNF. All probably different versions of aips...

Cheers
Chris