The Dominion Astrophysical Observatory Spectroscopic Plate and Science Archives

David Bohlender (National Research Council Canada), David Bohlender (NRC/HIA), Elizabeth Griffin (NRC/HIA)


The Dominion Astrophysical Observatory’s (DAO) photographic Archive contains almost exclusively Cassegrain or coudé spectra and includes 16,800 plates from the 1.2-m telescope (dating back to 1962) and the 93,000 or so from the 1.8-m telescope (commencing in 1918). The very great majority of the plates have never been digitized so as to yield an electronic transform of their spectroscopic information, and many will only have been measured for velocity, or studied in a semi-qualitative way. We have commenced a programme to digitize them with the DAO’s in-house PDS. The PDS has been upgraded so as to mesh well with the software routines that now pipeline the data. Scanning is being prioritized according to (a) demand, (b) data quality (c) the likelihood that an observation has the potential to return new science. The output spectra are fully calibrated in wavelength and in direct intensity, and can be downloaded in FITS format through a web site hosted by the CADC.

In a parallel effort, we have also developed an on-line archive for new data that continue to be acquired with both of the DAO telescopes. FITS files containing spectra or images are transferred automatically to the CADC storage system upon acquisition, and their associated metadata are ingested into CADC database tables. PIs can then search the DAO data collection using a typical CADC query page, and retrieve their raw proprietary data within minutes of the photons being collected by the telescope. Public CCD data from 2010 and earlier are also being added to the archive after their FITS header contents have been modified to meet the minimum requirements needed to enable archival searches and subsequent scientific exploitation.

These complimentary archiving efforts will provide a complete collection of safely archived DAO data for both telescopes, extending from 1918 to the present time for the 1.8-m telescope, and from 1962 to the present for the 1.2-m facility.

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Paper ID: P015

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