Cutout Image Service?

Science Data Q&A
#1

Last week the EuroBrokers (Ampel/Fink/Lasair) had a collaboration meeting, and we discussed cutout images. I was actioned to find out a bit more. Thank you for your responses!

We three brokers agreed that
– There will be a very large number of cutouts
– We do not envision massive mining of cutouts
– Rather it will be small scale “look and see” of the cutouts of interesting events
– To reduce the numbers, we are considering keeping only recent cutouts, perhaps 3 months

Therefore we would like to ask of the LSST project
– Will LSST run a cutout image service (CIO)?
– Is there anything in the LSST documentation I should be looking at?
– If there is a CIO, could we rely on it for cutouts more than 3 months old?
– Would there be a “do not abuse” policy for CIO, similar to the forced photometry service?
– Would a CIO be restricted to data rights holders?
– Would the pixels be the same as came with the alert, or would there be re-processing?

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#2

– Will LSST run a cutout image service (CIO)?

Requirement DMS-REQ-0094 (LSE-61 §4.1.14) obligates us to maintain an archive of alerts, including cutouts.

In addition, requirements DMS-REQ-0065 (LSE-61 §3.3.3) and DMS-REQ-0375 (LSE-61 §5.3.1.1) provide for an image cutout service that can be applied to processed visit images, difference images, and templates.

– Is there anything in the LSST documentation I should be looking at?

DMTN-183 describes the alert database design, from which cutouts (or “postage stamps”) could be retrieved. It does not currently contemplate separating cutouts from the rest of the alert packet, but that could be possible.

DMTN-139 §4 describing the general image cutout service is still in draft but will eventually contain more technical details.

– If there is a CIO, could we rely on it for cutouts more than 3 months old?

Yes, with caveats.

– Would there be a “do not abuse” policy for CIO, similar to the forced photometry service?

Yes, there may be rate limits (quotas) on the use of the cutout service. The overall limit and allocation to consumers has not yet been determined.

– Would a CIO be restricted to data rights holders?

At present, all Data Access Center services for non-public data, including the image cutout service, and most services for public data, including the alert database, are expected to be authenticated and restricted to data rights holders. This is a policy question, however, as we will have the technical ability to have unauthenticated services.

– Would the pixels be the same as came with the alert, or would there be re-processing?

The alert database will have the identical contents. The general image cutout service may have regenerated the base image for the cutout, but it must be “within scientifically reasonable tolerances” (DMS-REQ-0311, LSE-61 §4.1.9).

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