Published on November 1, 2007
The Italian and Vatican experience to digitize the Astronomical Photographic Archives: The Italian and Vatican experience to digitize the Astronomical Photographic Archives 1Department of Astronomy, University of Padova 2Specola Vaticana, Castelgandolfo 3INAF and University of Catania 4INAF Torino 5INAF Roma 6Department of Astronomy, University of Roma I 7 DLR Berlin, Germany 8Bulgarian Academy of Sciences, Sofia, Bulgary Cesare Barbieri1 ([email protected]) Carlo Blanco3, Beatrice Bucciarelli4, Andrea Di Paola5, Luciano Lanteri4, Gian Luca Li Causi5, Ettore Marilli3, Piero Massimino3, Stefano Mottola7, Roberto Nesci6, Alessandro Omizzolo2, Fernando Pedichini5, Francesca Rampazzi1, Corinne Rossi6, Ruggero Stagni1, Milcho Tsvetkov8, Roberto Viotti6 Introduction: Introduction Highly valuable information is stored in the photographic archives of many Italian Observatories and in the Specola Vaticana. Several plates date back to the end of the XIX Century. A proper digitization of this veritable treasury is therefore of paramount importance, both for its preservation and for the fuller exploitation of its scientific content. Among the many scientific objectives of the digitization, we have already undertaken the following tasks: · time history of variable stars in the Milky Way and in external galaxies, of AGNs and QSOs, · spectral classification over wide fields Some examples of achieved results will be presented in the following slides. Other possible scientific programs will be: · inventory of novae and supernovae in external galaxies, · search for past transits of asteroids and comets, for a better reconstruction of their orbital and physical evolution, . Fundamental catalogues, discovery and inventory of high proper motion stars. The Photographic Archives Census - 1: The Photographic Archives Census - 1 Table 1 gives the total inventory of the useful plates in the participating Italian Observatories: While the Asiago Observatory archive was always kept in a well ordered manner, the others have been fully reconditioned in the course of our project. Lacking (unfortunately) in the present collaboration are two large Italian archives: 1) Campo Imperatore, which is scattered among the different observers. 2) Bologna-Loiano (including Horn's d'Arturo with the segmented mirror), which is fortunately well ordered and kept. The Photographic Archives Census - 2: The Photographic Archives Census - 2 Table 2 gives the content of the Specola Vaticana archive, with plates coming from the astrograph in its historical locations and from the Schmidt telescope in Castelgandolfo. The Vatican archive is well preserved and ordered from the very first plate. For every plate of the Carte du Ciel and of the Astrographic Catalogue there is a detailed description of the characteristics, the plate constants to do astrometry, and information concerning exposure time and weather conditions. The digitization of the Schmidt logbooks is in progress by the Bulgarian Academy of Sciences in Sofia. The hardware - 1 : The hardware - 1 Several commercial scanners (produced by Epson) with retro-illumination, resolutions of 1600x3200 dpi, format A3 or A4, output at 14 or 16 bits, have been bought for Asiago, Padova, Catania, Rome and Castelgandolfo. The same scanners are used by DLR in Berlin and by several other European institutes. The scanners are connected via USB2 or FireWire to dedicated PCs. A typical working area. The hardware - 2: The hardware - 2 For imaging plates, Schmidt objective prism material and low resolution spectra (e.g. spectra taken with image intensifiers), useful work can still be done with the available equipment, as shown by the adjacent figure. However, for the fine grained spectroscopic plates of the Asiago 122-cm spectrograph and for the images on the S40/50 films, a higher resolution (4800x9600 dpi), smaller format scanner has been recently installed in Padova. Spectral types of 10th mag stars, from a digitized objective prism plate taken in 1972 with the Campo Imperatore Schmidt. The acquisition software: The acquisition software Programs that greatly enhance the ease of data acquisition, working in the Windows operating system and providing as output a positive or negative FITS image (including the header) that can be directly analyzed with IRAF, MIDAS or IDL, were initially written by S. Mottola (DLR), and implemented on all our machines. A. Di Paola (INAF Rome Observatory) has written another routine that automatically analyses the header and generates the .jpg previews from the FITS files. Typical digitization time for a S67 plate of 20x20cm is 7 minutes, the overall time raises to approximately 30 min per plate including inspection, handling and cleaning. Typical dimensions of the digitized plates at 1600 dpi range from 260 MB for 20x20 cm Schmidt plates to 70 MB for the 9x12 cm plates of the Asiago 122 cm telescope. AstroPlates: AstroPlates It generates contemporarily FITS and jpeg files (with a selectable compression factor), handles headers, images and catalogs. An example is shown in the figure. A Beta release is available to interested users. At Catania Observatory, another tool (AstroPlates) has been developed by P. Massimino in Visual Basic 6 for every 16-bit Windows ambient. AstroPlates requires IDL 5.4 or later versions. The CCD photometric program: The CCD photometric program The overall national program comprises as crucial element the acquisition of BVRI sequences in selected fields, by means of the CCD camera of the Campo Imperatore Schmidt telescope, which covers a field of approximately 1x1 sq. deg. Left: the CCD frames acquired in the M42 field. See later for more photometric details. The Asiago telescopes: The Asiago telescopes Left: the 122 cm, which operated both at the Newton and Cass focus. Right: the 182cm and the S67/92 cm at Cima Ekar, some 4km away; until 1991 the S67/92 was located next to the 122cm telescope, together with the S40/450. The Asiago Archive -1 : The Asiago Archive -1 The status of the Asiago archive : The status of the Asiago archive The digital logbooks of all the Asiago telescopes, and of the objective prism spectra of the S67/92-cm and S40/50-cm telescopes are accessible on-line (www.pd.astro.it/Asiago/7000/7020.html), with a query program. Some 2500 plates have been already digitized, their list can be found in a file on that page. Their utilization by the International community is already very active. The digital files are stored both on DVDs and in a 600 GByte Network Attached Storage unit that will be put on line in the near future, but already needs expansion. Left: the NAS unit. Right: one of the 3 Asiago working places. The first plates - 1: The first plates - 1 First plate with the 182 cm, and optical quality: First plate with the 182 cm, and optical quality Left, the first plate, March 8, 1973. Above: the excellent optical quality of the f/9 Cassegrain focus. The S67/92cm plate distribution, the Sa57 calibration curve: The S67/92cm plate distribution, the Sa57 calibration curve The S67/92cm distribution of plates is far from being evenly distributed.The limiting useful magnitude is around 18.5 (better than that until 1975). The light curve of 3C 345: The light curve of 3C 345 The Asiago Observatory carried out since 1967 a large scale survey of Quasar Variability. Many plates were acquired and reduced with traditional methods, but most of them were not published. We intend to redo this work on the digitized material. Here is an example for 3C 345 (Omizzolo, A., Barbieri, C., Rossi, C. 2005, MNRAS), left the light curve from 1967 until 1990, right the difference eye-scanner. But indeed, these plates contain some 50 more quasars (unknown at the time of the discovery of 3C 345), which we plan to analyze as soon as possible. The BL Lac Object S5 0716+714 : The BL Lac Object S5 0716+714 Another interesting paper on QSO variability is: The Long Term Optical Variability of the BL Lac object S5 0716+714: Evidence for a Precessing Jet (R. Nesci, E. Massaro, C. Rossi, S. Sclavi, M. Maesano, F. Montagni, Astron. Journal 2005), which used also the S40/50 films. The T-Tau KH 15 D star: The T-Tau KH 15 D star KH 15 D is a remarkable pre-main sequence binary star with deep long lasting periodic eclipses. BVRI Photometry of KH15D over the last five decades has been derived from several digitized photographic archives (including Asiago). Dr. J. Johnson (Berkeley) has produced and left in Asiago, after his stay, a very useful IDL-based photometric program that can handle entire batches of plates. (Johnson J.A., Winn N., Rampazzi F., Barbieri C., Mito H., Tarusawa T., Tsvetkov M., Borisova A., Meusinger H. (2005). The History Of The Mysterious Eclipses Of KH 15D II. Asiago, Kiso, Kitt Peak, Mt. Wilson, Palomar, Tautenburg And Rozhen Observatories, 1954-97 (2005). Astronomical Journal. McNeil's Nebula: McNeil's Nebula left: all B Asiago images right: all I Asiago images. The I-plates archive, obtained mostly by Paolo Maffei on Milky Way fields, is still largely unexplored. The Asiago archive has provided a very useful record of the brightening episode in 1967-68, excluding other more recent similar instances . (from C. Aspin, B. Reipurt and the Asiago staff, 2005, in preparation). Variables in M33 and M31: Variables in M33 and M31 The Asiago plates permit to study the Hubble-Sandage variables in M33 (top). The same is true for M31(bottom, Var. nr. 19 on 3 different plates). All plates of those two fields are already available in digital form. It's a very rich material which can be accessed by all interested astronomers. Three different plates of var. 19 in M31. Left: 182 cm, center 122 cm, right S67/92 cm. The misterious Of, X-ray star HD108: The misterious Of, X-ray star HD108 Only 3 such stars as HD108 are known. The Asiago material covers approximately 15 years from 1953 to 1967, from the very blue to H-alpha. Only the oldest plates have been examined and published (Mannino and Humblet, Annales d’Astrophysique 18e Année - N° 4, pag. 237-258, 1955, and Contributi Osservatorio Astrofisico Asiago nr. 89, 1958). Emission, absorptions, P-Cyg lines are well visible and measurable. More on the linearization procedure - 1: More on the linearization procedure - 1 (These results are essentially due to Andrea di Paola, Rome). To obtain linearization, we derive sets of secondary standards using the CCD camera of Campo Imperatore. Fig. 1a shows an example for an near-IR plate. The resulting characteristic curve has been fitted with a double exponential function like: and applied to each pixel of the digitized plate. More on the linearization procedure - 2: More on the linearization procedure - 2 The results show a 6 magnitudes useful dynamic range and less than 0.1 magnitudes standard deviation of residuals. We also verified that upon constant and good development conditions, all the plates from the same emulsion share the same characteristic curve and can be linearized using the same function. More on the linearization procedure - 3: More on the linearization procedure - 3 After having linearized all the available M42 plates from the Asiago Astrophysical Observatory archive obtained with the 103aO emulsion and the GG13 filter (very similar to Johnson B filter) we performed a variability search on a nearly 30 years period. This search produced many candidates besides confirming known objects such as Y-Ori, BV-Ori and TT-Ori. The Torino Archive (~6000 plates): The Torino Archive (~6000 plates) Old plates from OATo archive: Old plates from OATo archive The Pons-Winneke comet, M42, the Pleiades, plates exposed in 1927 at the Zeiss telescope of the Osservatorio Astronomico di Torino. Low resolution (600dpi) JPEG scans are provided for each archived plate. Inspection & Archiving at OATo: Inspection & Archiving at OATo Plates are inspected with a binocular microscope to check emulsion status and image quality. Plates are cleaned and stored in high-density polyethylene (HDP) envelopes for better protection. Plates archiving at OATo: Plates archiving at OATo Archive Room Measuring machine TO.CA.M.M. The Catania Archive: The Catania Archive ** only approximately 200 in acceptable conditions! A plate of the Carte du Ciel 1896: A plate of the Carte du Ciel 1896 Plate nr. 26, obtained on July 1, 1896, is still usable, but most have gone forever. Halley Comet and the great comet 1910a: Halley Comet and the great comet 1910a Upper left panel: the great australis comet1910a; The other 3 panels are of comet Halley. Lower panel: a digital Sekanina-type filter applied to one of the Catania images. Plates from the Vatican Archive - 1: Plates from the Vatican Archive - 1 A plate from the Astrographic Catalog. The logbooks were published. The archive is extremely well kept and ordered. Plates from the Vatican Archive - 2: Plates from the Vatican Archive - 2 An objective prism plate obtained with the Vatican Schmidt in Castelgandolfo. Many plates were taken in Milky Way fields with plate-filter-prism combination that effectively selected stars with Halpha emissions (e.g. G. Coyne et al., Vatican Observatory Publ. Vol. 1 nr. 5, 1974) Future plans (if funded…): Future plans (if funded…) complete the storage and the digitization of the log-books (almost finished in all places) continue to accept proposals from the International community, in order to selectively digitize those plates that give a maximum scientific return. The very nature of this project calls for its harmonisation with the concept of Virtual Observatory. The added value photographic plates can bring to the VO is to enhance the time axis of the VO multi-dimensional space. We plan to coordinate our work with the Italian activities for the Datagrid and national Virtual Observatory (DRACO). As such, the use of the standards defined within the working groups of the International VO Alliance (IVOA) is envisaged, and data are planned to be eventually accessible to the community at large through the VO.