How do I drizzle together long and short exposures?

sbrightsbright Member, Institute_Staff Posts: 2
I have many exposures from the same visit, however some have long exposures and a few are short. When I combine these images, the psf of the bright stars are corrupt. How can I accurately combine these images so that the flux of the bright stars is not compromised?


  • avilaavila Member, Institute_Staff Posts: 10
    It is difficult to drizzle together images with very different exposure times. The weighting scheme used by default can introduce inaccuracies in the PSF if the exposure times vary by more than a factor of ~2. It's probably best to make separate drizzled products for long and short exposures.
  • mutchlermutchler Member, Institute_Staff, Moderator_DrizzlePac Posts: 6
    edited December 2014
    I think even a factor of two in exposure times is a bit much. I wouldn't attempt to combine images with exposure times more than ~30% different. Fortunately, it usually seems like you have either a very small difference (well under 30%) or a very large difference (5x or 10x), so the choice is obvious.
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