The Italian and Vatican experience to digitize the Astronomical Photographic Archives

1
The Italian and Vatican experience to digitize
the Astronomical Photographic Archives
Cesare Barbieri1 (cesare.barbieri_at_unipd.it)
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
1Department of Astronomy, University of
Padova2Specola Vaticana, Castelgandolfo3INAF
and University of Catania4INAF Torino5INAF
Roma6Department of Astronomy, University of Roma
I7 DLR Berlin, Germany 8Bulgarian Academy of
Sciences, Sofia, Bulgary
2
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.
3
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.

4
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.
5
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.
6
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.
7
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.
8
AstroPlates
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.
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.
9
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.
10
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.
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The Asiago Archive -1
12
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/7000/70
20.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.
13
The first plates - 1
14
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.
15
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).
16
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.
17
The BL Lac Object S5 0716714
Another interesting paper on QSO variability
is The Long Term Optical Variability of the BL
Lac object S5 0716714 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.
18
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.
19
McNeil's Nebula
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).
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.
20
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.
21
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 dAstrophysique 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.
22
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.
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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.
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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.
25
The Torino Archive (6000 plates)
 
26
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.
27
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.
28
Plates archiving at OATo
Archive Room
Measuring machine TO.CA.M.M.
29
The Catania Archive
only approximately 200 in acceptable
conditions!
30
A plate of the Carte du Ciel 1896
Plate nr. 26, obtained on July 1, 1896, is still
usable, but most have gone forever.
31
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.
32
Plates from the Vatican Archive - 1
A plate from the Astrographic Catalog. The
logbooks were published. The archive is extremely
well kept and ordered.
33
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)
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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.