## Astronomical Photographic Data Archive (APDA) ##  Caption: Multiple views of the APDA, courtesy of PARI The [2007 Workshop on a National Plan for reserving Astronomical Photographic Data](http://aspbooks.org/custom/publications/paper/410-0033.html) (Osborn & Robbins 2009) recommended the establishment of the Astronomical Photographic Data Archive (APDA) at [Pisgah Astronomical Research Institute (PARI)]((https://www.pari.edu/)). Ideally, heritage materials should remain at the institution that created them; however, not all institutions are capable of maintaining extensive archives of fragile photographic plates. For these threatened collections, the adequate, climate-controlled APDA facilities can be a responsible solution.  Caption: Arial view of PARI; courtesy of PARI PARI, founded in 1998, is a non-profit, public foundation dedicated to providing hands-on educational and research opportunities for a broad cross-section of users in science, technology, engineering and mathematics (STEM) disciplines. The PARI facility was originally built in 1962 as a [National Aeronautics and Space Administration](https://www.nasa.gov/) (NASA) [satellite tracking station](https://www.pari.edu/about/our-history/). In 1981, [National Security Agency](https://www.nsa.gov/) (NSA) took over the site. In November 2007, an [astronomical photographic plate preservation workshop](http://aspbooks.org/custom/publications/paper/410-0033.html) was held at PARI (Osborn & Robbins 2009). Thirty-two astronomers from the United States of America, Canada and Europe met to discuss the preservation of the rich heritage of astronomical photographic observations, most of which are on glass plates. The workshop discussions resulted in recommendations, both to the astronomical community in general and to institutions holding astronomical plates, for ensuring preservation of these irreplaceable photographic and metadata records. The workshop also recommended that a national plate archive be established on the campus of PARI; thus, the APDA was born. APDA is dedicated to the collection, restoration, preservation and storage of astronomical photographic data.  Caption: PARI research building, which houses the APDA; courtesy of PARI ## Photographic Plate Collection ## As of 2021, over 419,000 plates, dating from 1898 to 1994, have found a home in APDA. APDA’s resources have * provided images for spectral analysis in STEM residential summer programs held at PARI * updated stellar coordinates in SIMBAD (Strasbourg CDS) * verified whom had first sighting of a comet * confirmed that the Kepler satellite mission’s KIC 8462852 light-curve peculiarities occurred at least 5 times prior to 2015 * demonstrated their value as spectral training images for artificial intelligence (AI) or machine learning (ML) though projects by undergraduate students at Carnegie Mellon University * served as surrogates for simulated Gaia BP/RP spectro-photometer images in pre-flight testing of the European Space Agency's (ESA’s) [Gaia](https://sci.esa.int/web/gaia) data analysis algorithms; [Hudec and Hudec (2011)](https://iopscience.iop.org/article/10.1088/1742-6596/328/1/012018/pdf) used actual spectral images obtained from digitized Schmidt spectral plates * provided stellar spectral images used in an online interactive stellar classification training site * provided photographs for a public outreach article on the Lost City Meteorite ([Pratt 2014](https://www.earthmagazine.org/article/benchmarks-january-3-1970-lost-city-meteorite-tracked-and-recovered)) ## Instruments for Use with Photographic Plates ##  Barker viewing image of [M 33 (NGC 598)](https://www.nasa.gov/feature/goddard/2019/messier-33-the-triangulum-galaxy) on a photographic plate (#2704) that was exposed in 1976 by the [Victor M. Blanco 4-meter telescope](https://noirlab.edu/public/programs/ctio/victor-blanco-4m-telescope/) at [Cerro Tololo Inter-american Observatory](https://noirlab.edu/public/programs/ctio/) (CTIO), Chile; courtesy PARI To make full use of the astronomical photographic plates stored on-site, PARI also maintains a collection of legacy instruments for viewing and measuring such images. For instance, [Space Telescope Science Institute (STScI)](https://www.stsci.edu/) donated the light table used in the picture above. The microscope includes a digital camera that connects to a computer. ## Photographic Films ##  Caption: (upper) Image from [Smithsonian Astrophysical Observatory (SAO)](https://www.si.edu/unit/astrophysical-observatory) Meteorite Photography and Recovery Project (MRP) photographic film negative used in predicting "Lost City Meteorite" impact location, (lower) image of recovered meteorite, both images courtesy of PARI. In addition to its extensive glass plate archive, the APDA also holds approximately 11,000 10"x10" photographic film negatives and envelopes. In 2007, the APDA received all the photographs made during the 12-year the SAO MRP (a.k.a. Prairie Meteorite Network; [McCrosky & Boeschenstein 1965](https://articles.adsabs.harvard.edu/pdf/1965SAOSR.173.....M_)). [Sara Pratt (2014)](https://www.earthmagazine.org/article/benchmarks-january-3-1970-lost-city-meteorite-tracked-and-recovered) used APDA images in her popular article about the Lost City Meteorite and its recovery. On 1970 Jan 3, the Prairie Meteorite Network recorded a bright meteor on four cameras. Within four days, the SAO team delineated a landing zone near Lost City, OK. The team found a 9.83 kg piece of the meteorite, one with minimal earthly contamination. The [Lost City Meteorite](https://meteorites.asu.edu/meteorites/lost-city) was the only meteorite found in 12-year life of the Prairie Meteorite Network ([McCrosky et al. 1971](https://articles.adsabs.harvard.edu/pdf/1971SAOSR.336.....M)). The APDA also has about 35,000 Harvard-Smithsonian Meteor Survey films taken with the Baker Super Schmidt near [White Sands Proving Grounds](https://wsmrmuseum.com/2020/09/21/a-brief-history-of-white-sands-proving-ground-1941-1965/2/), New Mexico, in the 1950's. If digitized, these 52° films could be searched with AI/ML techniques to identify new gamma-ray bursts and other transient phenomena.  Caption: Looking north across the PARI campus; courtesy of PARI ### References ### McCrosky, R. E. & Boeschenstein, H. 1965, "The Prairie Meteorite Network," SAO Special Report, 173, bibcode: [1965SAOSR.173.....M](https://ui.adsabs.harvard.edu/abs/1965SAOSR.173.....M/abstract) McCrosky, R. E., Posen, A., Schwartz, G., et al. 1971, "Lost City Meteorite - its Recovery and a Comparison with Other Fireballs," SAO Special Report, 336, bibcode: [1971SAOSR.336.....M](https://ui.adsabs.harvard.edu/abs/1971SAOSR.336.....M/abstract) Hudec, René & Hudec, Lukáš. 2011, "Tests of simulated Gaia BP/RP spectra with LDS (Low Dispersion Spectroscopy) photographic sky surveys," *J Phys: Conf. Ser.*, 328, id. 012018, bibcode: [2011JPhCS.328a2018H](https://ui.adsabs.harvard.edu/abs/2011JPhCS.328a2018H/abstract), doi: [10.1088/1742-6596/328/1/012018](https://doi.org/10.1088/1742-6596/328/1/012018) Osborn, W. & Robbins, L. 2009, "[Preserving Astronomy's Photographic Legacy: Current State and the Future of North American Astronomical Plates](http://aspbooks.org/custom/publications/paper/410-0033.html)," *Preserving Astronomy's Photographic Legacy: Current State and the Future of North American Astronomical Plates*, ASP Conf. Ser. 410, edited by W. Osborn & L. Robbins. San Francisco: ASP, bibcode: [2009ASPC..410...33O](https://ui.adsabs.harvard.edu/abs/2009ASPC..410...33O/abstract) Pratt, S. E. 2014, "Benchmarks: January 3, 1970: Lost City meteorite is tracked and recovered," Earth Magazine (Alexandria, VA: American Geosciences Institute) available online [https://www.earthmagazine.org/article/benchmarks-january-3-1970-lost-city-meteorite-tracked-and-recovered](https://www.earthmagazine.org/article/benchmarks-january-3-1970-lost-city-meteorite-tracked-and-recovered)