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lukeshingles / atlasserver

ATLAS forced photometry server
https://fallingstar-data.com/forcedphot/
MIT License
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Populate the Forced Photometry Server FAQ #14

Closed genghisken closed 3 years ago

genghisken commented 3 years ago

The question about difference flux over long periods, step changes in the photometry, and possible mitigations comes up all the time. Can we turn this into an FAQ please? (See recent email about this.) There's only one FAQ on our FAQ page!

lukeshingles commented 3 years ago

Do you want to suggest a particular wording for the Q and A, or should I attempt to generalise it myself?

genghisken commented 3 years ago

Maybe something like:

Q: Why are there step discontinuities in the difference flux lightcurve when requested over a long period of time (e.g. years)?

A: The difference image reference templates are periodically replaced. In order to see whether the step change is real you might want to consider requesting "reduced" (i.e. input) image data. If there are no discontinuities in this lightcurve, the likelihood is that the step features are present because of the template change.

lukeshingles commented 3 years ago

Thanks. Added now!