Request to consider adding Rubin pointing information to the DPDD/prompt data products


I’ve always assumed in some shape or form the pointing history of LSST and the 5 sigma limiting depth estimated by the prompt data products processing pipelines would be accessible in some form daily, so one could determine if some interesting comet should have been spotted in a specific Rubin Observatory observation that was taken the night before while the survey was happening, and then at data release there would be a separate pointing database with the data release.

I could see the limiting magnitude and pointing information being useful especially for early science with the alert stream.

Looking at the DPDD (Data Products Definition Document), there is no pointing information described. The visit table was pointed out to me, but that does not seem to include an estimate of the limiting magnitude of the image.

Could Data Management and Operations consider whether this information about vist metadata and estimate of the limiting magnitude derived from prompt processing should be available daily and on a data release timescale? And if this information will be accessible can it be briefly described in the DPDD?



Do you mean “ability to look up where we have observed” or do you mean “a history of the pointing accuracy of the telescope”. The ObsTAP service will be able to make the former available although I’m not sure when the public view will sync up with what actually happened. We also intend to run a service reporting the next visit we will observe so that other telescopes can look where we are looking.

I think that’s a safe assumption, yes, that visit pointings and their 5-sigma limiting magnitude image depths will be available daily (and annually).

You’re right that this not explicitly stated in the DPDD at the moment, which just says the Prompt Catalogs “will also contain exposure and visit metadata … [that] are either standard/uncontroversial, implementation-dependent, or less directly relevant for science and therefore not discussed in this

This is a great LSST data question so I’m going to move this topic to the “Data Q&A” category, to help me bring it to the attention of the Data Management System Science Team, so that we can discuss how to make the details of the planned metadata like this more accessible to the community.

But until then, I think go ahead and make plans for science assuming that kind of data would be available.

I mean the contents of the rubin_sim (scheduler) database that has pointing, the metadata, and 5-sigma limiting magnitude. Index of /~lynnej/opsim_downloads/fbs_2.0/baseline - I would say past and current year pointing history and estimates of the limiting magnitude.

And delivered PSF FWHM or some other seeing measurement. The alert stream would be measuring that as well as an estimate of the limiting magnitude (for point sources). Since these values actually do change per amp and location in the FOV, but I’m guessing for a ‘visit metadata table’ and for most user’s purposes it’d be a lot easier and likely adequate to deal with just one value, maybe we can figure out some representative value for the visit to use.

I intend to include add Rubin metadata in the list of archives indexed by the Solar System Object Image Search, which would meet your comet use case. At the moment, SSOIS does not keep track of things like PSF FWHM or magnitude limit. However this is because (almost) none of the archives currently indexed by SSOIS ave those parameters. It would be pretty easy to add them.

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