Editing Digitized Sky Survey

{{Short description|Digitized astronomical surveys}}
{{Distinguish|Sloan Digital Sky Survey}}
{{Infobox astronomical survey}}
The '''Digitized Sky Survey''' (DSS) is a [[digital data|digitized]] version of several [[photography|photographic]] [[astronomical survey]]s of the [[night sky]], produced by the [[Space Telescope Science Institute]] between 1983 and 2006.

== Versions and source material ==
The term Digitized Sky Survey originally referred to the publication in 1994 of a digital version of an all-sky photographic atlas used to produce the first version of the [[Guide Star Catalog]].<ref>B. Lasker, "Digitized Optical Surveys at STScI", [http://www.stsci.edu/files/live/sites/www/files/home/news/newsletters/_documents/1994-volume011-issue02.pdf ''STScI Newsletter'' '''11''' No. 2], 39 (1994)</ref><ref>{{Cite journal |last1=Lasker |first1=Barry M. |last2=Sturch |first2=Conrad R. |last3=McLean |first3=Brian J. |last4=Russell |first4=Jane L. |last5=Jenkner |first5=Helmut |last6=Shara |first6=Michael M. |date=June 1990 |title=The Guide Star Catalog. I. Astronomical Foundations and Image Processing |url=https://ui.adsabs.harvard.edu/abs/1990AJ.....99.2019L |journal=The Astronomical Journal |volume=99 |pages=2019 |doi=10.1086/115483 |bibcode=1990AJ.....99.2019L |issn=0004-6256}}</ref> For the northern sky, the [[National Geographic Society – Palomar Observatory Sky Survey]] E-band (red, named after the [[Eastman Kodak]] IIIa-E [[Photographic emulsion|emulsion]] used), provided almost all of the source data (plate code "XE" in the survey).<ref>{{Cite web|url=https://archive.stsci.edu/dss/booklet_n.pdf|title=The Digitized Sky Survey: Discs 62–102 The Northern Hemisphere|website=archive.stsci.edu|access-date=2018-06-09}}</ref> For the southern sky, the J-band (blue, Eastman Kodak IIIa-J) of the [[European Southern Observatory|ESO]]/[[Science and Engineering Research Council|SERC]] Southern Sky Atlas (known as the SERC-J, code "S")<ref>R. M. West, "The Southern Sky Surveys—A review of the ESO Sky Survey Project", [https://www.eso.org/public/unitedkingdom/products/bulletins/bulletin_0010/ ESO Bulletin '''10'''], 25 (1974)</ref><ref name="cannon1984">{{Cite book |last=Cannon |first=Russell D. |title=Astronomy with Schmidt-Type Telescopes |chapter=Sky Surveys with the UK 1.2m Schmidt Telescope |date=1984 |editor-last=Capaccioli |editor-first=Massimo |chapter-url=https://link.springer.com/chapter/10.1007/978-94-009-6387-0_3 |series=Astrophysics and Space Science Library |volume=110 |language=en |location=Dordrecht |publisher=Springer Netherlands |pages=25–35 |doi=10.1007/978-94-009-6387-0_3 |isbn=978-94-009-6387-0|s2cid=197456149 }}</ref><ref name="roe">{{Cite web|url=http://www.roe.ac.uk/ifa/wfau/ukstu/platelib.html|title=The Plate Library at the Royal Observatory, Edinburgh|website=www.roe.ac.uk|access-date=2018-08-12}}</ref> and the "quick" V-band (blue or V in the [[UBV photometric system|Johnson–Kron–Cousins system]], Eastman Kodak IIa-D) SERC-J Equatorial Extension (SERC-QV, code "XV"), from the [[UK Schmidt Telescope]] at the Australian [[Siding Spring Observatory]], were used.<ref>{{Cite web|url=https://archive.stsci.edu/dss/booklet_s.pdf|title=The Digitized Sky Survey: Discs 1–61 The Southern Hemisphere|website=archive.stsci.edu|access-date=2018-08-12}}</ref> Three supplemental plates in the V-band from the SERC and Palomar surveys are included (code "XX"), with shorter exposure times for the fields containing the [[Andromeda Galaxy]], the [[Large Magellanic Cloud|Large]] and the [[Small Magellanic Cloud]].<ref>{{Cite web|url=https://archive.stsci.edu/dss/faq.html|title=MAST DSS FAQ|website=archive.stsci.edu|access-date=2018-08-16}}</ref> The publication of a digital version of these photographic collections has subsequently become known as the First Generation DSS or DSS1.

After the original 1994 publication, more digitizations were made using recently completed photographic surveys, and released as the Second Generation DSS or DSS2. Second Generation DSS consists of three spectra bands, blue, red, and [[near infrared]]. The red part was first to complete,<ref>{{Cite web|url=https://www.eso.org/sci/facilities/paranal/instruments/sinfoni/inst/faq.html|title=Frequently Asked Questions|website=www.eso.org|access-date=2018-08-16}}</ref> and includes the F-band (red, Eastman Kodak IIIa-F) plates from the [[Palomar Observatory Sky Survey II]], made with the [[Oschin Schmidt Telescope]] at [[Palomar Observatory]] for the northern sky.<ref>{{Cite journal |last1=Djorgovski |first1=S. G. |url=https://ui.adsabs.harvard.edu/abs/1998wfsc.conf...89D |title=The Palomar Digital Sky Survey (DPOSS) |last2=Gal |first2=R. R. |last3=Odewahn |first3=S. C. |last4=de Carvalho |first4=R. R. |last5=Brunner |first5=R. |last6=Longo |first6=G. |last7=Scaramella |first7=R. |journal=Wide Field Surveys in Cosmology |date=1998 |volume=14 |page=89 |location=eprint: arXiv:astro-ph/9809187|arxiv=astro-ph/9809187 |bibcode=1998wfsc.conf...89D }}</ref><ref>{{Cite journal |last1=Gal |first1=R. R. |last2=Carvalho |first2=R. R. de |last3=Odewahn |first3=S. C. |last4=Djorgovski |first4=S. G. |last5=Mahabal |first5=A. |last6=Brunner |first6=R. J. |last7=Lopes |first7=P. a. A. |date=December 2004 |title=The Digitized Second Palomar Observatory Sky Survey (DPOSS). II. Photometric Calibration |journal=The Astronomical Journal |language=en |volume=128 |issue=6 |pages=3082 |doi=10.1086/344941 |bibcode=2004AJ....128.3082G |s2cid=14464066 |issn=1538-3881|doi-access=free |arxiv=astro-ph/0210298 }}</ref><ref>{{Cite journal |last1=Odewahn |first1=S. C. |last2=de Carvalho |first2=R. R. |last3=Gal |first3=R. R. |last4=Djorgovski |first4=S. G. |last5=Brunner |first5=R. |last6=Mahabal |first6=A. |last7=Lopes |first7=P. A. A. |last8=Moreira |first8=J. L. Kohl |last9=Stalder |first9=B. |date=December 2004 |title=The Digitized Second Palomar Observatory Sky Survey (DPOSS). III. Star-Galaxy Separation |journal=The Astronomical Journal |language=en |volume=128 |issue=6 |pages=3092–3107 |doi=10.1086/425525 |bibcode=2004AJ....128.3092O |s2cid=17114755 |issn=0004-6256|doi-access=free }}</ref> Red band sources for the southern sky include the short red (SR) plates of the SERC I/SR Survey and Atlas of the Milky Way and Magellanic Clouds (referred to as AAO-SR in DSS2),<ref>{{Cite journal |last1=Hartley |first1=M. |last2=Dawe |first2=J. A. |date=1981 |title=The SRC Near-Infrared Survey of the Galactic Plane |url=https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/abs/src-nearinfrared-survey-of-the-galactic-plane/9B0B59DB5AF37253CCFE6179B02DEA3B |journal=Publications of the Astronomical Society of Australia |language=en |volume=4 |issue=2 |pages=251–254 |doi=10.1017/S1323358000016532 |bibcode=1981PASA....4..251H |s2cid=115232835 |issn=1323-3580|url-access=subscription }}</ref> the Equatorial Red (SERC-ER),<ref name="cannon1984"/> and the F-band Second Epoch Survey (referred to as AAO-SES in DSS2, AAO-R in the original literature),<ref>{{Cite book |last1=Morgan |first1=D. H. |last2=Tritton |first2=S. B. |last3=Savage |first3=A. |last4=Hartley |first4=M. |last5=Cannon |first5=R. D. |title=Digitised Optical Sky Surveys |chapter=Current and Future Programmes with the UK Schmidt Telescope |date=1992 |editor-last=MacGillivray |editor-first=H. T. |editor2-last=Thomson |editor2-first=E. B. |chapter-url=https://link.springer.com/chapter/10.1007/978-94-011-2472-0_3 |series=Astrophysics and Space Science Library |volume=174 |language=en |location=Dordrecht |publisher=Springer Netherlands |pages=11–22 |doi=10.1007/978-94-011-2472-0_3 |bibcode=1992ASSL..174...11M |isbn=978-94-011-2472-0}}</ref> all made with the UK Schmidt Telescope at Anglo-Australian Observatory.<ref>{{Cite web|url=http://archive.eso.org/dss/dss|title=ESO Online Digitized Sky Survey|website=archive.eso.org|access-date=2018-06-09}}</ref>

== Production ==
The Digitized Sky Survey was produced by the Catalogs and Survey Branch (CASB) of the [[Space Telescope Science Institute]] (STScI). They scanned plates using one of two [[Perkin-Elmer]] PDS 2020G [[microdensitometer]]s. The [[pixel]] size was 25 ("First Generation", DSS1) or 15 [[micrometre]]s ("Second Generation", DSS2), corresponding to 1.7 or 1.0 [[arcseconds]] in the source material.<ref>{{Cite web|url=https://archive.stsci.edu/dss/|title=MAST DSS|website=archive.stsci.edu|language=en|access-date=2018-06-09}}</ref> The scanning resulted in images 14,000 x 14,000 (DSS1) or 23,040 x 23,040 pixels (DSS2) in size,<ref>{{Cite web|url=https://irsa.ipac.caltech.edu/data/DSS/|title=DSS Data Collection Atlas|website=irsa.ipac.caltech.edu|language=en|access-date=2018-06-09}}</ref> or approximately 0.4 (DSS1) and 1.1 [[gigabyte]]s (DSS2) each. The scanning of First Generation DSS takes a little under seven hours per plate to complete. Due to the large size of the images, they were compressed using an H-transform algorithm.<ref>{{Cite journal |last1=Fritze |first1=K. |last2=Lange |first2=M. |last3=Möstl |first3=G. |last4=Oleak |first4=H. |last5=Richter |first5=G. M. |date=1977 |title=A scanning microphotometer with an on-line data reduction for large field Schmidt plates |url=https://onlinelibrary.wiley.com/doi/10.1002/asna.19772980402 |journal=Astronomische Nachrichten |language=de |volume=298 |issue=4 |pages=189–196 |doi=10.1002/asna.19772980402|bibcode=1977AN....298..189F |url-access=subscription }}</ref><ref>{{Cite journal |last1=Capaccioli |first1=M. |last2=Held |first2=E. V. |last3=Lorenz |first3=H. |last4=Richter |first4=G. M. |last5=Ziener |first5=R. |date=1988 |title=Application of an adaptive filtering technique to surface photometry of galaxies. I. The method tested on NGC 3379 |url=https://onlinelibrary.wiley.com/doi/10.1002/asna.2113090202 |journal=Astronomische Nachrichten |language=de |volume=309 |issue=2 |pages=69–80 |doi=10.1002/asna.2113090202|bibcode=1988AN....309...69C |url-access=subscription }}</ref> This algorithm is lossy, but adaptive, and preserves most of the information in the original.<ref>{{Cite book |last1=White |first1=R. L. |last2=Postman |first2=M. |last3=Lattanzi |first3=M. G. |title=Digitised Optical Sky Surveys |chapter=Compression of the Guide Star Digitised Schmidt Plates |date=1992 |editor-last=MacGillivray |editor-first=H. T. |editor2-last=Thomson |editor2-first=E. B. |chapter-url=https://link.springer.com/chapter/10.1007/978-94-011-2472-0_22 |series=Astrophysics and Space Science Library |volume=174 |language=en |location=Dordrecht |publisher=Springer Netherlands |pages=167–175 |doi=10.1007/978-94-011-2472-0_22 |bibcode=1992ASSL..174..167W |isbn=978-94-011-2472-0}}</ref> Most of the First Generation DSS files were shrunk by a factor of seven.<ref>{{Cite web|url=http://gsss.stsci.edu/zzzOldWebSite/DSS/dss_home.htm|title=Digitized Sky Survey|website=gsss.stsci.edu|access-date=2018-06-09}}</ref> Similar methods were used in the production of the "Second Generation" DSS, but the microdensitometers have since been modified for multi-channel operation, in order to keep the scan time under 12 hours per plate.<ref>{{cite book | chapter-url=https://doi.org/10.1007/978-94-011-1146-1_36 | doi=10.1007/978-94-011-1146-1_36 | chapter=Digitization Programs at STScI | title=Astronomy from Wide-Field Imaging | date=1994 | last1=Lasker | first1=B. M. | pages=167–171 | isbn=978-0-7923-2879-7 }}</ref>

The CASB has also published several companion scientific products. The most notable is a [[photometry (astronomy)|photometric]] calibration of part of the "First Generation" DSS. It allows photometric measurements to be made using the digital northern POSS-E, southern SERC-J, and southern Galactic Plane SERC-V data.<ref>{{Cite web|url=http://gsss.stsci.edu/zzzOldWebSite/DSS/PHOTOMETRY/INDEX.HTML|title=DSS Photometric Calibrations|website=gsss.stsci.edu|access-date=2018-06-09}}</ref>

== Publication ==
The compressed version of the First Generation DSS was published by the STScI and the [[Astronomical Society of the Pacific]] (ASP) on 102 CD-ROMs in 1994, under the name "Digitized Sky Survey."<ref>{{Cite journal |date=1994 |title=Availability of the Digitized Sky Survey on CD-ROMs |url=https://doi.org/10.1086/133354 |journal=Publications of the Astronomical Society of the Pacific |volume=106 |pages=108 |doi=10.1086/133354 |bibcode=1994PASP..106..108. |s2cid=127582827 |issn=0004-6280|url-access=subscription }}</ref> It has also been made available online by the STScI<ref>{{Cite journal |last=Morrison |first=J. E. |date=1995 |title=Accessing the Digitized Sky Survey |url=https://ui.adsabs.harvard.edu/abs/1995ASPC...77..179M |journal= Astronomical Data Analysis Software and Systems IV|volume=77 |pages=179|bibcode=1995ASPC...77..179M }}</ref><ref>{{Cite web|url=https://archive.stsci.edu/cgi-bin/dss_form|title=The STScI Digitized Sky Survey|website=archive.stsci.edu|access-date=2018-08-14}}</ref> and several other facilities in databases that can be queried over the web. The moniker "First Generation" was added later.

In 1996, a more highly compressed version of the DSS was published by the STScI and ASP under the name RealSky. RealSky files were compressed by a factor of roughly 100. RealSky consequently took up less space, but the additional compression made it inappropriate for use in photometry and fine detail in the images was degraded.<ref>{{Cite web|url=http://www.bisque.com/Products/realsky/realsky.asp|title=Software Bisque|website=www.bisque.com|language=en|access-date=2018-06-09}}</ref><ref>{{Cite web|url=http://hubblesite.org/news_release/news/1996-20|title=The Original National Geographic Society - Palomar Observatory Sky Survey to be Available on 8 CD-ROMs|website=hubblesite.org|language=en|access-date=2018-08-14}}</ref>

The Second Generation DSS has appeared steadily over the course of several years. In 2006, the Second Generation DSS (second epoch POSS-II and SES surveys) was finished, and distributed on [[CD-ROM]] to partner institutions. Generally, the data are available through WWW services at partner institutions.

== Funding ==
{{columns-list|colwidth=30em|
*[[Association of Universities for Research in Astronomy]]
*[[Anglo-Australian Observatory]]
*[[Beijing Astronomical Observatory]]
*[[Canadian Astronomical Data Center]]
*[[Centre de Donnee Stellaire]]
*[[European Southern Observatory]]
*[[Gemini Observatory]]
*[[Hohenkarpfen Observatory]]
*[[National Astronomical Observatory of Japan]]
*[[Palomar Observatory]]
*[[Royal Observatory Edinburgh]]
*[[Space Telescope Science Institute]]
}}

== See also ==
{{columns-list|colwidth=30em|
*[[Guide Star Catalog]]
*[[Pan-STARRS]]
*[[Sloan Digital Sky Survey]]
*[[SkyMapper]]
*[[2MASS|Two Micron All-Sky Survey]]
}}

== References ==
{{Reflist}}

== External links ==
* [http://archive.stsci.edu/cgi-bin/dss_form Digitized Sky Survey]
* [http://www.worldwidetelescope.org/webclient A Seamless Spherical Stitch of the Digitized Sky Survey from Microsoft Research]
* [http://www.google.com/sky/#latitude=30.595&longitude=131.491666&zoom=8 Digitized Sky Survey in Google Sky (partly covered by SDSS and other images)]
* [http://www.wikisky.org Digitized Sky Survey in WIKISKY.ORG]

{{Astronomical Surveys}}
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[[Category:Astronomical catalogues]]
[[Category:Astronomical surveys]]
[[Category:Astronomical databases]]