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Catania Observatory contributions and results

The Catania photographic archive consists of direct images (no spectra) taken in the original location in town (Piazza Vaccarini) and more recently on the Serra La Nave (Mt. Etna station, now M.G. Fracastoro station) of the Catania Observatory. The old plates were stored in wooden boxes without any protection, and many have been lost to humidity and fungi; now, chemically inert envelops have been procured, and a complete restoration procedure will be attempted when possible. For the moment a more suitable site for the preservation of the old historical plates has been predisposed and a control of the type of damage of their emulsions has been made in collaboration with the Institute of Phytopathology of the Agricolture Faculty of Catania University. It has been put in evidence that, for the plates not completely ruined, an efficient restoration will be possible with the aid of photochemical technics only in laboratories specialized for the recovery of old photographic materials.

The plates considered worth of digitization are detailed as in the following:

In addition to these the detailed inspection of the plate photographic archive of Catania Observatory has concurred to pick out approximately 1200 image plates, taken in the period from 1897 to 1940 in the site of Piazza Vaccarini with the equatorial astrograph. More than 800 of these plates are in good conditions for the digitation process, however for the large part of them it is not possible to recover logbooks or sufficient informations for an efficient informatic archiving.

A complete building of informatic archives and digitation in FITS formats has been made for all the plates acquired at the S41/61 telescope. The images were stored both in a dedicated fixed hard disk and on DVD-r portable supports.

A complete digitation of the plates of Halley comet was also made, while only a small sample of plates taken for the Astrophotgraphic Project was digitized.

It has been used a work station dedicated to the informatic archiving of the plates and of the observation logbook and to the first examination of the material available for the digitation. The station has been equipped with a commercial scanner with high performances of type EPSON 1680pro, in analogy with other italian observatory participant to the project. These types of scanner, with back-illuminated system, give real resolutions of 1600x3200 DPI, format A3 or A4, output to 14 or 16 bit.

The digitation of the plates was performed by using a software tool developed at the Astrophysical Observatory of Catania, named AstroPlates, a program that takes advantage of MS Visual Basic 6.0. It runs in any 32 bit Microsoft environment. AstroPlates acquires the images in TIFF format, either in B/W (14-16 bit/pixel) or RGB (14-16 bit/pixel for each channel). In the latter case the program is able to isolate a single channel. In the next step the images are transformed in FITS (with appropriate header), JPG or Bitmap format. It is also possible to record plate information in MDB database. An important characteristic of the program is the use of the powerful development environment IDL and its libraries by using the OCX component of IDL to communicate with it and to take advantage of its graphical and numerical capabilities. All functions of AstroPlates use the IDL libraries without activating the IDL environment. Therefore, it is not necessary that the user knows this language and its functions. During the acquisition phase it is possible to optimize the scanner parameters by a procedure taking into account the analysis of frequency histograms of grey levels in the plate.


next up previous contents index
Next: Projects and Collaborations Up: The digitization of the Previous: The digitization of the   Contents   Index
Innocenza Busa' 2005-11-14