[daip] CLCOR, OPCODE 'ANTC'

[Leonia Kogan]

Dear Andreas,

Yes your data has the original SU table. I found the problem and sent 
the fix to the AIS system. It will be available to you through MNJ tomorrow.

The problem:

You data probably were correlated at EVN (not at Socorro) and this makes 
a difference at RA of SU table being determined athe range -180,+180, 
while the data correlated at Socorro get the RA at SU table at the range 
0,360.
SO CLCOR having met negative RAEPO adds the given correction converts it 
to the negative RAAPP and get the correction at RAAPP of the order 
360degrees (~1.e+6asec)
So I fixed it adding 360 degrees to the negative RA.

But it is not the whole story.

The Socorro correlator create SU table with DECEPO and RAEPO leaving 
blank at RAAPP, DECAPP. FITLD takes care about RAAPP, DECAPP. We tested
the calculation of RAAPP, DECAPP carefully.

The your data correlator (EVN probably) creates both epoch and apparent 
collumn for the SU table and as Isee the apparent coordinates have a 
difference with FITLD of the order of 200asec.

That is why the new version still shows the difference of ~200asec at
correction of apparent coordinates

SO
1. Use now ANTP now because CLCOR always apply correction to CL table on 
the basis of apparent coordinate correction!
2. Investigate calculation of apparent coordinates at your data

LK
Andreas Brunthaler wrote:

> Hi Leonid,
> 
> I think this is the original Su Table. But I might be wrong. I have to
> check tomorrow when I am in my office.
> 
> Thanks,
> Andreas
> 
> On 5/14/07, Leonia Kogan <lkogan at nrao.edu> wrote:
> 
>> Andreas Brunthaler wrote:
>>
>> > Dear Leonid,
>> >
>> > here is my TASAV file. I noticed that it goes wrong if you run clcor 
>> for
>> > the first time. If you run it a second time it is ok.
>>
>> Such a behavior leads me to the conclusion that the original SU table of
>> your data is wrong. As you know CLCOR rewrites the SU table for ANTP and
>> ANTC.
>> I will be able to look CLCOR using your data only tonight. I am sorry.
>> Tell me now:Are the data you sent me has the original SU table or
>> corrected one by CLCOR?
>>
>> And please answer on my previous questions
>>
>> LK
>>
>>
>> >
>> > I used this input:
>> >
>> > task 'clcor'
>> >  antenna  0
>> >  gainver  2
>> >  gainuse  2
>> >  stokes   ''
>> >  bif      0
>> >  eif      0
>> >  opcode   'antc'
>> >
>> >  source   'on1'
>> >  clcorprm 0,0,0,0,-1.616,1.346,0
>> > go; wait
>> >
>> > Cheers,
>> > Andreas
>> >
>> >
>> > Leonia Kogan wrote:
>> >
>> >>Dear Andreas,
>> >>
>> >>I tried CLCOR with my data and got the right answer!
>> >>So
>> >>
>> >>1. Try CLCOR using your data with AIPS version 'new'
>> >>2. Ran aips task TASAV to keep only attached tables and send me the
>> >>tasav'ed UV data
>> >>
>> >>LK
>> >>Andreas Brunthaler wrote:
>> >>
>> >>
>> >>>Dear Leonid,
>> >>>
>> >>>I have noticed some strange behaviour of CLCOR with OPCODE 'ANTC'
>> >>>recently for some EVN data:
>> >>>
>> >>>CLCOR1: Task CLCOR  (release of 31DEC07) begins
>> >>>CLCOR1: CL version input   2 output   2
>> >>>CLCOR1: SOUMOD: change in Epoch    RA,DEC -1.61600E+00  1.34600E+00 
>> asec
>> >>>CLCOR1: SOUMOD: change in Apparent RA,DEC  1.10493E+06  6.34087E+01 
>> asec
>> >>>CLCOR1: !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> >>>CLCOR1: !!! SU table is corrected for the selected source. !!!
>> >>>CLCOR1: !!! So you should apply the corrected CL table     !!!
>> >>>CLCOR1: !!! to match the data. See HELP.                   !!!
>> >>>CLCOR1: !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>> >>>CLCOR1:    390 Records modified
>> >>>CLCOR1: Appears to have ended successfully
>> >>>
>> >>>While the shift in 'Epoch' is correct, I get a shift of 1.1E+06
>> >>>arcseconds in 'Apparent'.
>> >>>
>> >>>Was the task changed recently? I remember that I always used 'ANTP' to
>> >>>change the 'Epoch'-Position.
>> >>>
>> >>>Cheers,
>> >>>Andreas
>> >>>
>> >>
>> >>
>> >
>> >
>>
>>
>>