[Issues] Problems with Global Astrometry

[John P. McFarland]

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
> 
>
>