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HiPERCAM / hipercam

Python package for handling HiPERCAM data
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hpackage #99

Closed tariq-shahbaz closed 2 years ago

tariq-shahbaz commented 2 years ago

Sometimes hpackage does not add the WCS information to the headers. CCD 1: missing positional data; no WCS added whereas using joinup there seems to be no problem.

It would be used to print out what header items are missing in hpackage.

trmrsh commented 2 years ago

Hi Tariq, was this not in fact a problem? (I have an ambition to attempt a more generalised astrometric solution to all hipercam / ultracam etc data, but don't wait up)

tariq-shahbaz commented 2 years ago

Hi Tom

Mmm, yes you could say that. In the end I used "hpackage" package to create the fits files on the individual CCDs (with the bias and flats in the same directory, tar=yes) then then unpacked the tar file.

After plotting the i-band images taken on different nights, I have noticed that the WCS are different. Stars are not in the same position (see chart attached). Shame as I wanted to plot the position of possible brown dwarfs and it would save a lot of hassle if I could just use the HiPERCAM WCS . Not sure how you can do this if you do not have stars in the field you can use for calibration.

Maybe I am doing something silly in python!, but I am seeing Vik next week and hopefully he or Stu can help

Cheers

Tariq

p.s.

AR Sco, found it in my spam! I am still at the IAC.

On Wed, 18 May 2022 at 09:55, Tom @.***> wrote:

Hi Tariq, was this not in fact a problem? (I have an ambition to attempt a more generalised astrometric solution to all hipercam / ultracam etc data, but don't wait up)

— Reply to this email directly, view it on GitHub https://github.com/HiPERCAM/hipercam/issues/99#issuecomment-1129750041, or unsubscribe https://github.com/notifications/unsubscribe-auth/AZECRYALQVO6ZL7JQ72DPS3VKSWBTANCNFSM5WBNEY3Q . You are receiving this because you modified the open/close state.Message ID: @.***>

trmrsh commented 2 years ago

The WCS I apply is really crude -- it just comes straight from the telescope, so absolutely no surprise to hear that the stars "move". The WCS needs to be tweaked from the star positions -- you might know how to do this better than me. My long term aim is to use astrometry.net, but that is long term. The existing method is just a stop gap.