ASIAGO SCIENCE ARCHIVE DATABASE
PHOTOGRAPHIC ARCHIVE INFORMATION
A great amount of highly valuable information is stored in the Asiago
Observatory photographic archive, with plates dating back to 1942 and
reaching 1994, when the use of photographic material was discontinued
at all telescopes (with few exceptions in the following years until 1998).
The University of Padova started in 2001 a pilot project to digitize
the plates; in 2002 further funds were allocated by the Italian Ministry
of University and Research to a collaboration involving also the Observatories
of Torino, Monte Porzio (Rome) and Catania, the University of Rome I and
the Specola Vaticana at Catelgandolfo (MIUR/COFIN 2002 to C.Barbieri, Dpt. of Astronomy, University of Padova).
The original log-books of the Asiago photographs have been well kept and ordered. Their content has been almost entirely transferred to electronic files available in PDF and ASCII format. Note that in the 122-cm spectroscopic logs and in all the 182-cm logs, U.T. is given at mid exposure.
In the '40s and '50s, different Italian emulsions were used; we have not been able to find data sheets on their characteristics. From the '60s, mostly Eastman-Kodak emulsions were used, whose spectral response is as in Fig. 1.
Fig. 1. The spectral sensitivity of the Eastman-Kodak emulsions used in Asiago
Emulsion -E (not shown in the figure) was intermediate between
D and F, and was often used to define the R-band in conjunction with the
Schott filter RG1.
Scanning Hardware and File Size
At present, digitation is performed with 3 commercial scanners: two Epson
1640 XL, A3 format, optical resolution 1600x3200 dpi, 14 bit/px and one
Epson Perfection 3200 PHOTO, 3200x6400 dpi, 16 bit/px for an area of 4x9
Tests have been performed on different types of plates, both with images and spectra, to determine the effective spatial resolution of the scanners. The result is 16 micron/px at 1600 dpi, which is sufficient for direct image and objective prism plates, while for spectroscopic material and for the Schmidt 40/50 plates, the resolution of 3200 dpi is necessary, with 8 micron/px.
The approximate dimensions of the digitized files at 1600 dpi are:
The size of the files poses a serious problem, both for storage and for
distribution. At the moment, we are storing the files to a Network Attached
Storage (NAS) unit, using as backups DVDs of 4.7 GB each. The NAS unit
accepts NFS, FTP and Windows protocols. The present capability is 540
GB, in configuration RAID 5 without hot spare, and it can be expanded
to 0.8 TB.
An Excel file with a list of already digitized plates is updated regularly.
FITS sample detail (right-click to download, 3.6 MB)
ARCHIVE QUERY PAGE | 182-cm COPERNICO | GALILEO 122-cm SCHMIDT 67/92 | SCHMIDT 40-50cm