SCAN-IT Issue 2 Editorial
Elizabeth Griffin, Chair, IAU PDPP Working Group

        Welcome to another SCAN-IT Newsletter!  Once again, we are bringing you a mixed bag: project reports and updates, discussions of the scientific requirements to be met when designing or selecting a scanner for digitizing plates, and some thoughts about the fate of unwanted or unreturned -- even of returned! -- plates.  How can the community best organize itself to return plates to the home observatory when no-one there has a responsibility for receiving and sorting them?  Is it better to wait until a "final home" is decided for each and every archive before shipping small personal collections? These may not be weighty matters, but they need well-researched answers nonetheless.

The Project grows

        As the reports from the IAU and the AAS meetings indicate, the PDPP community is growing, both numerically and in its involvement in the management of its historic resource.  That cannot but be a good thing.  The hope is that organizations and individuals with really deep pockets will get to hear about how Astronomy is trying to save its heritage, and may be not unready to listen to our appeals.  Already some acquaintances have mentioned hearing astronomers report on projects to digitize plates, and did I know?  -- so the word is spreading.  This is really very encouraging.

Scientific Drivers

          Most of the submitted articles concentrate on the  How of digitizing observations; little coverage has been given so far to the Why, which is of course ultimately what drives the scanning efforts.  It is high time to redress the balance, and we would like to encourage readers to collect two types of input: (a) references to results that were only achievable through an ability to access digitized photographic observations, and (b) a wish list of ideas for scientific topics that would benefit from -- or only be possible through -- such access, and submit them to the PARI listserver (PARI listserver}.  The lists that are thus collected will form a valuable reference for anyone writing a proposal to digitize plates.

          Recently when I needed to produce a list of scientific accomplishments that depended on accessing photographic data, I searched the ADS for combinations of the words ``photographic --observations--digitize", and was pleasantly surprised to find a considerable number of examples, many of which were in the current year.  Synopses of some of them fill up odd corners of this Newsletter.  Researchers are quick to take advantage of new resources, and the publicity given of late to digitizing plates seems to be bearing rapid fruit.  So please keep the reports and the ideas flowing in.  In this issue, page 15 contains notes on two specific instances where access to plates helped solar-system research, while page 16 pleads the case for access to historical spectra in order to understand long-term Be-star phenomena.

PARI, a Center for North American Plates.

          Do visit the PARI Website at, and read about the amazing facilities there, and the plans to generate a large-scale plate archive and digitizing centre.

The Future of Astronomy's Past.

          The following article derives from a Discussion Meeting held during the IAU General Assembly in Sydney, 2003.  Attended by about 40 people, the discussion touched on a variety of specific issues: a central repository for plates, recalling "personal" collections, on-line catalogues of archive contents, and buying versus building an appropriate type of scanner.

         Astronomy has a Past.  In about 3 million pieces, in fact.  Photographic plates, in cabinets, drawers, boxes, shelves.  Enveloped, labelled, protected.  Evidence of events never to recur, of changes once witnessed and now eagerly sought to confirm or condemn a theory.  Astrometry across a time-base of 60, 80, 100 years; asteroids on trajectories that may not after all collide with Earth; photometric changes of order half to one magnitude over a period of 20 years; surveys of the sky dating back to the 1920s or earlier (IVOA please note!); unique information regarding the evolution of the Earth's ozone.

          Historic material is an invaluable complement to modern research, and to date most of our historic observations cannot be incorporated in research because the material is non-digital.  The 40 or so people who attended the Round Table discussion last Tuesday were in no doubt about the crying need to rescue that mine of information before it deteriorates and is lost to perdition (or to an observatory trash-bin), nor in our ability to rise to that challenge.  We took it as read that such steps, extensive and expensive as they might be, are an essential prerequisite both for the health of our science and for our credibility as guardians of its unique heritage.

          Two sites have been identified as "area locations" for storing direct plates which an observatory no longer can or wishes to keep: Brussels Observatory in Europe, and PARI (North Carolina) for North American plates.  Both sites will be furnished with high-speed scanners, and will operate digitizing programmes with instruments selected according to the inherent accuracy of the original material.  Some observatories are already operating their own digitizing programmes, and may wish to deposit the scanned plates in an "area location" for long-term preservation.

          Because spectra present a whole different set of requirements, they will be handled separately by the Spectroscopic Virtual Observatory (SVO), planned for the DAO (Canada).  However, the SVO does not have the capacity to store plates indefinitely, and scanned material will also be sent to PARI.

          What about ownership of the material and of the digital datasets?  Presumably plate archives can be donated to a scanning operation, but the simplest formula is undoubtedly "long-term loan".  And if we abide by the prevailing ethos for scientific data, all the products of the scanning labs will be free, just as other digital data are today free worldwide.

          But don't leave it all to the people in the scanning labs.  Theirs is a Herculean task.  To proceed in orderly and rigorous fashion they need on-line inventories of the plate collections.  Since we are organizing your digitizing for you, we welcome your help in putting the log-books or card catalogues on-line.  Obviously it is important to adopt the same formats, and we can supply templates and instructions.

          And what should you do about those "foreign" plates that have been lying in your office, measured or otherwise, for perhaps decades?  Undoubtedly it would be better to return them to the observatory of origin while you can still exercise control over the matter; your post-retirement replacement or your executor will lack your knowledge and your plate-handling expertise.  Actually the time for a major plate-recall is not yet ripe, as few observatories have plate archivists -- though some do.  Please contact for possible information, and rest assured that your plates ARE wanted back.  If the observatory had no log-book formalities, then please locate your own observing notes and send them, on-line.

          There's no denying that it will take resources -- skilled, trained humans -- to carry out digitizing programmes and manage the digital databases, and that means Money; the same commodity will be absorbed by plates in long-term storage.  But the figures are orders of magnitude smaller than the cost of a new telescope or a space mission.  Many an instrument is funded to solve just one question; historic data will be a resource for solving any number of questions.  Specific scientific discoveries which historic data will enable may be hard to predict as many will be serendipitous, but the IVO faces exactly the same challenge, and many countries are willing to translate their faith there into investment.

          Attitudes towards historic observations were still ambivalent at the Manchester GA, but a clear sense of purpose has now emerged - and the relevant technology has improved in the interim.  As scientists we cannot afford NOT to carry this project through, and the time to begin is NOW.  Yes, astronomy has a Past, but that Past can have an important Future for research, teaching and outreach and in the IVO.

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