Astrometry Correction of the DASCH scanned photographic plates

Servillat, Mathieu

The DASCH project (Digital Access to a Sky Century at Harvard) will give access to long-term light-curves (up to 100 years) of sources detected in half a million plates stored at the Harvard College Observatory. In order to extract such light-curves without confusion, one requirement is to obtain a good astrometric solution with an accuracy lower than 3 pixels or better for each plate. This will ensure that cataloged object are correctly recovered for each plate, and that non-cataloged objects are securely isolated as new peculiar events.

I will present the steps of the DASCH pipeline that allow to blindly derive an astrometric solution for each scanned plate using Astrometry.net and SCAMP. We show that about 95% of the plates can be corrected with a better accuracy than the 3 pixels requirement.

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