[Issues] Problems with Global Astrometry

[John P. McFarland]

Dear Anna,

We are attempting to figure out what is going on, but we cannot access the 
reduced data shown in the logs.  It is probably just in your private 
context.  Could you provide the particulars of the data you are using and a 
description of the procedures you are using (e.g., query parameters and 
command lines).

My initial impression is that the problem may be data dependent (cf., the 
"too few reference/overlapping stars" warnings from the logs).  Once we see 
what data you are using and how you are using it, we should be able to 
figure out what is happening.

Cheers,


-=John


On Mon, 2 Jul 2007, John P. McFarland wrote:

> Dear Anna,
>
> This is indeed a strange problem.  We are looking into it and will reply
> again once we have more information.
>
> Cheers,
>
>
> -=John
>
>
> On Fri, 29 Jun 2007, anna romano wrote:
>
>> Hi all,
>>
>> here in Naples we have problems with Global Astrometry.
>> For example when we tried to process the Sikkema data, the CCD50 does not
>> appear in the final mosaic and the astrometry is wrong in the other CCDs.
>> As an example these are the Astrometric Parameters produced before and after
>> Global Astrometry for some exposures/CCDs:
>>
>> After AstrometricParametersTask:
>>
>> Exposure  filter      chip       instr         CD1_1                 CD1_2
>> CD2_1               CD2_2            1         #878       ccd50     WFI
>> -6.620125e-05     3.788299e-07      2.344569e-07      6.592619e-05
>>   2         #878     ccd50     WFI     -6.628069e-05       1.63594e-07
>> 2.694998e-07      6.602958e-05
>>   1         #878     ccd51    WFI     -6.593424e-05     -7.156799e-08
>> -3.319406e-07      6.602225e-05      2         #878     ccd51    WFI
>> -6.628551e-05      3.087525e-08     6.657912e-08       6.593517e-05
>> After GAstromTask:
>>
>> Exposure  filter      chip       instr         CD1_1                 CD1_2
>> CD2_1               CD2_2            1         #878    ccd50    WFI
>> 0.001523728     -0.00641293      0.002444735    -0.01029184      2
>> #878    ccd50    WFI     0.001523728     -0.006415796    0.002443643
>> -0.01029184      1         #878    ccd51    WFI    -6.596957e-05     0
>> 0                        6.598252e-05      2         #878    ccd51    WFI
>> -6.596956e-05     0                      0
>> 6.598253e-05
>>
>> Similar results are systematically produced for other fields: as you see, the
>> astrometric parameters are good before gastrom, and completely wrong
>> afterwards.
>> Do you know what could be the reason and do you have any advice?
>> We also give in attachment an excerpt of the log produced by GAstrom: it
>> seems that for some reason it does not find reference/overlapping sources.
>> Of course, please tell us if we can send you anything else which may be
>> useful.
>>
>> Thanks a lot in advance.
>>
>>    Anna Romano
>>
>>
>>
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