[daip] CLCOR SU table update problem (?)

[Leonia Kogan]

At the previous message I forgot to include the name of the package used by 
SCHED. It is STARLINK and it is independent on AIPS (JPRECS specifically).

Sorry.

Leonia

>You comparison to SCHED is difficult for me to interpret.  I do not know
>the accuracy of SCHED's coordinate transforms.

Craig Walker told me that SCHED uses rather precise program based on STARLINK

>I am also not familiar with TSPOS (which is not in our AIPS installation)
>so here to I cannot interpret the results, especially your description of
>what you did with APARM(9).

TSPOS is a simple task which calculates aparent coordinates using JPRECS and 
then recalculates them back to J2000. The task prints the initial J2000, 
the apparent and recalculated J2000 coordinates at hh(deg);mm:ss.
TSPOS prints also the difference of the initial and recalculated J2000 
coordinates  at mas.

Originally TSPOS carried out the apparent coordinates calculation for the 
relevant midnight. To calculate the apparent coordinates for the given time 
of the day I added APARM(9) in days. At the test I used time=20:54:45.
So APARM(9) = 0.8713 days.

>I presume the VLBA correlator has essentially perfect routines. Can the 
>results of that code be compared to what you and I have calculated?

Yes this is a good idea. I'll speak with John Benson about such a test.

Thanks

Leonia


----- Begin Included Message -----

>From lincoln at play.harvard.edu Thu Oct 11 07:43 MDT 2001
Date: Thu, 11 Oct 2001 09:43:23 -0400 (EDT)
From: Lincoln Greenhill <lincoln at play.harvard.edu>
To: Leonia Kogan <lkogan at zia.aoc.NRAO.EDU>
cc: daip at cv3.cv.nrao.edu
Subject: Re: [daip] CLCOR  SU table update  problem (?)
In-Reply-To: <200110102056.OAA08526 at bonito.aoc.nrao.edu>
MIME-Version: 1.0
X-Lines: 35
Status: RO


Hi Leonia,

Your test of coordinate transforms with TSPOS and SCHED are interesting.

My code gives the following results, which differ by on the order of
20 mas from yours:

 J2000                                  14:28:32.6600   42:40:20.6000   
 2001 doy185 20:54:45 w/ GR correction  
 LJG                                    14 28 36.1099   42 40 16.2532
 TSPOS                                  14:28:36.1109   42:40:16.2703

You comparison to SCHED is difficult for me to interpret.  I do not know
the accuracy of SCHED's coordinate transforms.  In principle, a
VLBI scheduling program does not need particularly high precision
routines.

I am also not familiar with TSPOS (which is not in our AIPS installation)
so here to I cannot interpret the results, especially your description of
what you did with APARM(9).  Perhaps SCHED and TSPOS use similar NRAO
code, so the test runs you performed are not really independent?

I have tried to use the USNO NOVAS package to obtain an independent third
opinion as to the apparent coordinates but it gives a segmentation fault
on workstations here.

I presume the VLBA correlator has essentially perfect routines. Can the 
results of that code be compared to what you and I have calculated?

Regards,

Lincoln




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