«AMERICAN ASTRONOMICAL SOCIETY WORKING GROUP ON THE PRESERVATION OF ASTRONOMICAL HERITAGE CENSUS OF ASTRONOMICAL PHOTOGRAPHIC PLATES IN NORTH AMERICA ...»
AMERICAN ASTRONOMICAL SOCIETY
WORKING GROUP ON THE PRESERVATION OF ASTRONOMICAL HERITAGE
CENSUS OF ASTRONOMICAL PHOTOGRAPHIC PLATES IN NORTH AMERICA
October 10, 2008 ©2008
Prepared by W. Osborn and L. Robbins
A census of astronomical photographic plates in North America was carried out to determine the number of existing plates as well as their locations, conditions, availability for research and other relevant information. Two hundred and four census forms were distributed to observatories, astronomy departments and a few individual astronomers. There was a 50% overall response rate, which included full or partial responses from all of the major U.S. and Canadian organizations.
The census identified over 2.4 million photographs. Forty-four institutions reported holding at least some photographic plates, however the 16 largest collections account for 97% of the total.
Canadian institutions hold roughly a third of the spectral plates. A number of conclusions about photographic plate archives are drawn from the census data.
Background For over 100 years – roughly from the mid 1880’s to the mid 1980’s – photography was the primary means of recording astronomical observations. The result was an estimated three million or more photographs worldwide, most of which are on glass plates. The photos include direct images of objects and star fields, objective prism spectral survey plates and slit spectrograms.
Well over half of the direct images and a large majority of the spectra were exposed at North American Observatories.
Astronomical institutes and observatories have traditionally archived and maintained the plates taken with their instruments along with the associated observing records – date, time, emulsion type, etc. – necessary to interpret them. While many institutions have only small collections of plates, some major observatories have over 100,000 images dating back over 100 years. There are also plates held by individual astronomers. Plates generally have been considered the property of the observatory where they were taken, but plates have often been on indefinite loan to the investigators who took them, especially plates taken at the national observatories (e.g., KPNO and CTIO).
Unfortunately, the future of this unique archival record is presently unresolved, and this material is in danger of being lost. Increasingly, many astronomical institutions no longer have the space, resources, expertise and/or interest to maintain a plate archive. Consequently, some material is deteriorating because of poor storage conditionswhile in a few cases plate collections have actually been discarded. Further, some institutions are no longer prepared to deal with returned plates and therefore no longer desire to have their loaned plates returned. This raises the question of what should be done with plates held by institutions that are not their own and plates held by individuals when they are no longer being used, often when the astronomer retires or dies.
The PARI workshop With National Science Foundation (NSF) support, a workshop was held on November 1-3, 2007, to discuss the preservation of the rich heritage of photographic observations in North America.
The venue was the Pisgah Astronomical Research Institute (PARI) in Rosman, North Carolina.
PARI had previously been identified as an excellent potential site for a national astronomical plate archive. The workshop location therefore gave the participants, most of whom were not familiar with PARI, an opportunity to see and critically evaluate its suitability for a leading role in any preservation plan.
Thirty-two persons from twenty astronomical institutions took part in the discussions. These included persons responsible for major plate collections, representatives of observatories engaged in plate preservation efforts, astronomers with an interest in archival plates for research and a science historian as well as the NSF program officer and PARI staff. The main results from the
workshop were a series of recommendations. The first recommendation was:
Given the eventual need for a database of astronomical photographic data, a census of North American astronomical photographic plates should be carried out. This would be done by conducting a survey of observatories and other institutions known or expected to hold plates.
A detailed summary of the Workshop discussions and the recommendations can be seen at http://www.pari.edu/library/astronomical-plate-center/workshop/results/Summary.pdf and http://www.pari.edu/library/astronomical-plate-center/workshop/results/Recommendations.pdf The WGPAH In response to concerns raised by its Historical Astronomy Division, the American Astronomical Society established a Working Group on the Preservation of Astronomical Heritage (WGPAH) in January 2007 (see http://members.aas.org/comms/wgpah.cfm). The WGPAH is charged with “developing and disseminating procedures, criteria and priorities for identifying, designating, and preserving astronomical structures, instruments, and records so that they will continue to be available for astronomical and historical research, for the teaching of astronomy, and for outreach to the general public.” An appendix to the document proposing a Working Group elaborated on the charge by providing a list of matters that would be considered under the general areas of historically significant sites, historically significant instruments and archives. Astronomical photographs are specifically mentioned under the archives area.
Given the Working Group’s charge, the Census was eventually carried out under its general auspices. Specifically, then WGPAH chair (S. McCluskey, term 2007-2008) and the two members of the WGPAH whose appointments were based on interest in archival astronomical data (E.
Griffin and W. Osborn) were involved in developing the census form and were signatories of the cover letter seeking participation.
The Census of Astronomical Photographic Plates in North America
After the recommendation that a census be carried out was adopted at the PARI Workshop, a committee was selected to conduct it. Members were S. McCluskey (West Virginia U./WGPAH chair), E. Griffin (DAO/WGPAH member), W. Osborn (CMU/WGPAH member), M. Castelaz (PARI), R. J. Patterson (U. Virginia) and L. Robbins (U. Toronto). The committee worked by email to develop the census instrument and methods.
The Census form The Committee established the following basic parameters for the instrument that would be used to
conduct the census:
• The survey form should be short enough and easy enough to complete to encourage a high response rate
• The form should capture sufficient information to identify the locations and conditions of the major plate collections in North America
• The census would focus on traditional astronomical plates – direct images, objective prism plates and slit spectra – not on specialized collections such as solar images, planetary patrol plates, aurora films, etc.
It was decided to use e-mail as the primary mode for distributing the census forms and receiving the responses.1 Eventually two versions of the form were prepared, one for institutions and a slightly modified one to be sent to individual astronomers believed to have personal plate collections. In both cases, the form could easily be completed by filling in one’s responses on the e-mail message or an attached survey form and replying to the sender.
The census form had 14 questions. The first question was “Does your institution hold a collection of astronomical photographic plates?” The instructions were that if the answer was “No” then one should skip the rest of the questions but return the survey. If the answer was “Yes” the thirteen additional questions should be answered. These sought basic information on the collection, recent research or other use of the plates and thoughts on the collection’s future. Finally, there was a table that was to be completed listing for each plate series in the collection the telescope employed, types of plates (direct or spectra), and their estimated number, date range and condition.
A cover letter was included with each distributed census form. This explained the purpose of the survey, asked that it be returned by the deadline and provided some information on completing and returning it. The standard cover letter was sometimes modified for the particular recipient (e.g., the letter to observatory directors differed from the one sent to institutional archivists). A copy of the standard cover letter and census form are given in Appendix A.
The option to use paper and regular mail was made available, but only one response was received by this means.
The Distribution List The census was limited to institutions in North America, i.e. in Canada, Mexico or the United States.2 The distribution list was developed using two approaches. First, the personal knowledge of the committee members was used to identify institutions known to currently have plate collections or which had them in the past as well as some individual astronomers thought likely to hold plates.
Second, a list of presently or previously active astronomical observatories was developed by looking at observatory listings and reports in the astronomical literature. Table 1 gives the sources used, which range from 1907 to 2000. Comparison of the entries allowed an estimate of the activity level and longevity of a given observatory. Observatories with a primary focus on solar, planetary or non-optical observations were not included.
The final distribution list can be roughly divided into five general categories:
• Astronomical observatories and programs known to have had active photographic programs. We selected the following 28 institutions in this category: Steward Observatory/University of Arizona3, Cerro Tololo Inter-American Observatory (CTIO), Kitt Peak National Observatory (KPNO), Dearborn Observatory/Northwestern University, Indiana University, Harvard College Observatory and the Smithsonian Astrophysical Observatory, Lowell Observatory, Lick Observatory, Mt. Wilson Observatory/Carnegie Observatories, Palomar Observatory, University of Illinois Astronomy Department, University of Michigan Astronomy Department, Perkins Observatory/Ohio State and Ohio Wesleyan Universities, Allegheny Observatory/ University of Pittsburgh, Dyer Observatory/Vanderbilt University, University of Hawaii Institute for Astronomy, McDonald Observatory/University of Texas Astronomy Department, Leander McCormick Observatory/University of Virginia Astronomy Department, Yale University Astronomy Department, U. S. Naval Observatory – Washington, U.S. Naval Observatory – Flagstaff Station, Warner and Swasey Observatory/Case Western Reserve University, Van Vleck Observatory/ Wesleyan University, Sproul Observatory/Swarthmore College and Yerkes Observatory/University of Chicago in the U.S., the Dominion Astrophysical Observatory Cerro Tololo Inter-American Observatory, managed by AURA and which has many of its plates in North America, was also included.
Including telescopes and observing facilities on Mt. Bigelow, Mt. Lemmon, Tumamoc Hill and in the Catalina Mountains and David Dunlap Observatory/ University of Toronto in Canada and the Tonantzintla Observatory in Mexico.
• Astronomical institutions that have not carried out photographic observations but hold significant numbers of plates. We identified two in this category: the Pisgah Astronomical Research Institute (PARI) and the Space Telescope Science Institute (STScI). Just subsequent to the mailing of the survey, STScI disposed of all of their institutional plates by shipping them to Harvard. A few Institute astronomers have personal plate collections
• Other astronomy institutions that may have engaged in photographic work or hold plates.
These are mainly university astronomy/astrophysics/physics-astronomy departments that were active before 1990, by which time photography was largely discontinued. Some were known to have plates, for others no information was available. Examples are the astronomy departments at the University of Florida, University of Iowa, and San Diego State University.
• Institutions active in the photographic era but no longer in operation. In some of these cases we wrote to the successor department or institution, in others to the appropriate institutional archives, and in a few cases to a retired astronomer that was associated with the institution. Examples are the observatories of Georgetown University and Creighton University. In three cases4 a successor institution could not be identified.
• Individual astronomers known or believed likely to have individual plate collections.
E-mailing of the census forms commenced the first week of April 2008 with an April 30th return deadline specified. If no response had been received by the last days of April, a reminder was sent and selected non-responders contacted by telephone. Two hundred and four census forms were eventually distributed, including 19 to individual astronomers. The distribution list is given in Appendix B.
Results from the Census
Of the 204 distributed forms, the published e-mail addresses for six were invalid and we could not locate alternate ones. From the remaining 198, we received 90 written responses and 12 responses in our follow up telephone calls, yielding a 50% rate of response. This rate is, however, somewhat misleading as we surveyed a large number of smaller astronomy programs and some institutional archives at institutions with defunct observatories. Furthermore, we were able to obtain partial information for some non-responding institutions from other sources. For example, a number of institutions were known to have transferred most or all of their plate collections to another observatory5; available information for these cases was added to the census data under the institution currently holding the collection if not already reported.