Delegate Assembly Lightcurve Breakoutroom Summary 7-16-21

Here’s a brief summary of what was talked about in the lightcurve breakout room in the DP0 delegate assembly 7-16-21 led by Jeff Carlin and Leanne Guy:

  • A notebook tutorial is currently being written to explain how to make lightcurves.
  • In the meantime, the 4th tutorial notebook - Intro to Butler, is the best resource for preparing to make lightcurves.
  • Since the images available via TAP are all the 5 year CoAdd images, you can only use the src catalog to access PVIs which is available through the Butler.
    (PVI - processed visit image (single visit image after processing). This is also called calexp - calibrated exposure)
    To brute force a lightcurve, one could theoretically query all images with a particular track and patch and crossmatch the sources across PVIs.
  • Two potentially useful notebooks which could be modified to make lightcurves for DP0 are: StackClubCourse/DataProductsToScience.ipynb at master · LSSTScienceCollaborations/StackClubCourse · GitHub and StackClub/AsteroidLightCurve.ipynb at master · LSSTScienceCollaborations/StackClub · GitHub
  • This topic will be revisited in the second hour of the next delegate assembly since 30+ people attended the breakout session.

Please feel free to add anything I missed, alternate explanations, or other relevant resources to making lightcurves!


I think it will also be very interesting to develop a notebook that can produce forced photometry light curves. It will certainly be a good exercise but not clear if it will be faster/easier (probably not).

forced photometry on visits has not been processed in DC2. We only processed forced photometry on coaddition. I presume that it would be possible to take a reference band in the object catalog and fit a flux model on all the visits for a given object detected in this band.

1 Like

Thanks for the helpful recap, Natasha!

Very minor correction:

PVI - processed visit image (single visit image after processing). This is also called calexp - calibrated exposure

It’s actually “calexp,” which I’ve seen as “CalExp” here and there as well. For more on this, see the DPDD: DP0.1 Data Products — Vera C. Rubin Observatory Documentation for Data Preview 0.1.


PS: Oops, I see you’ve fixed it since first posting. I’m just leaving this for the DPDD link.