[daip] forwarded message from Chris Phillips

[Eric Greisen]

Maybe we should give an option to shift the epoch or the apparent...

In the former we would have to compute the shift in apparent from the
shift in epoch and use that for the phases.

ERic
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From: Chris Phillips <Chris.Phillips at csiro.au>
To: Eric Greisen <egreisen at cv3.cv.nrao.edu>
Subject: Re: [daip] Re: CLCOR
Date: Tue, 26 Nov 2002 15:24:09 +1100 (EST)

On Mon, 25 Nov 2002, Eric Greisen wrote:

>     LISTR uses the epoch positions straight from the SU table handled
> in double precision - at least for its SCAN listing.  In fact, that is

The "LISTR" position difference was exactly as you suspected. I was not
using enough precision in PRTAB. Sigh, this is about the millionth time I
have made this error. (repeat 100 times, "I will alway use enough
precision").

So the RAEPO position in the SU table agree with what LISTR gives.

Looking at the numbers again, the APPARENT positions *are* shifted by the
amount I request in CLCOR. However the shift in the EPO (epoch?) positions
is a little different. The arcsec changes (comparing before and after
running CLCOR) are:
 EPO: 9.6785, -5.5650
 APP: 9.1943, -5.5500

If the apparent positions change by the requested amount, does this mean
CLCOR has done the right thing? If so, I have to admit I don't really
understand but I am happy to take you word (and sorry for wasting your
time!).

Cheers
Chris



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