Editing Palomar Observatory (section)

==Research==
[[File:18 Inch Schmidt Camera at Palomar Observatory.jpg|thumb|The now decommissioned 18-inch Schmidt Camera]]

Palomar Observatory remains an active research facility, operating multiple telescopes every clear night, and supporting a large international community of astronomers who study a broad range of research topics.

The [[Hale Telescope]]<ref name="HALE" /> remains in active research use and operates with a diverse instrument suite of optical and near-infrared [[spectrometers]] and imaging [[cameras]] at multiple [[focus (optics)|foci]].  The Hale also operates with a multi-stage, high-order [[adaptive optics]] system to provide [[diffraction]]-limited imaging in the near-infrared.  Key historical science results with the Hale include cosmological measurement of the [[Hubble Flow|Hubble flow]], the discovery of [[quasars]] as the precursor of [[Active Galactic Nuclei]], and studies of [[stellar populations]] and [[stellar nucleosynthesis]].

The Oschin and 60-inch telescopes operate robotically and together support a major [[transient astronomy]] program, the [[Zwicky Transient Facility]].

The Oschin was created to facilitate astronomical reconnaissance, and has been used in many notable [[astronomical survey]]s—among them are:

===POSS-I===
The initial [[National Geographic Society - Palomar Observatory Sky Survey|Palomar Observatory Sky Survey]] (POSS or POSS-I), sponsored by the [[National Geographic Society|National Geographic]] Institute, was completed in 1958. The first plates were exposed in November 1948 and the last in April 1958. This survey was performed using 14-inch<sup>2</sup> (6-[[degree (angle)|degree]]<sup>2</sup>) blue-sensitive (Kodak 103a-O) and red-sensitive (Kodak 103a-E) photographic plates on the Oschin Telescope. The survey covered the sky from a [[declination]] of +90° ([[Celestial pole|celestial north pole]]) to −27° and all [[right ascension]]s and had a sensitivity to +22 [[apparent magnitude|magnitude]]s (about 1&nbsp;million times fainter than the limit of human vision). A southern extension extending the sky coverage of the POSS to −33° [[declination]] was shot in 1957–1958. The final POSS I dataset consisted of 937 plate pairs.

The [[Digitized Sky Survey]] (DSS) produced images which were based on the photographic data developed in the course of POSS-I.<ref>Minnesota Automated Plate Scanner (MAPS): [http://aps.umn.edu/ MAPS catalogue]; Mollise, Rod. (2006). {{Google books|Z0mvZk0s_TMC|''The Urban Astronomer's Guide: a Walking tour of the Cosmos for City Sky Watchers'' |page=238}}</ref>

J.B. Whiteoak, an Australian radio astronomer, used the same instrument to extend POSS-I data south to −42° [[declination]]. Whiteoak's observations used the same field centers as the corresponding northern declination zones. Unlike POSS-I, the [[Whiteoak extension]] consisted only of red-sensitive (Kodak 103a-E) photographic plates.

===POSS-II===
{{Redirect|Second Palomar Observatory Sky Survey|POSS I|Palomar Sky Survey}}

The '''Second Palomar Observatory Sky Survey''' ('''POSS II''', sometimes '''Second Palomar Sky Survey''') was performed in the 1980s and 1990s and made use of better, faster films and an upgraded telescope. The Oschin Schmidt was upgraded with an achromatic corrector and provisions for autoguiding. Images were recorded in three wavelengths: blue (IIIaJ. 480&nbsp;nm), red (IIIaF, 650&nbsp;nm), and near-infrared (IVN, 850&nbsp;nm) plates.  Observers on POSS II included C. Brewer, D. Griffiths, W. McKinley, [[J. Dave Mendenhall]], K. Rykoski, [[Jeffrey L. Phinney]], and [[Jean Mueller]] (who discovered over 100 supernovae by comparing the POSS I and POSS II plates). Mueller also discovered several comets and minor planets during the course of POSS II, and the bright Comet Wilson 1986 was discovered by then-graduate-student C. Wilson early in the survey.<ref>Caltech: [http://www.astro.caltech.edu/~wws/poss2.html The Second Palomar Observatory Sky Survey (POSS II)] {{webarchive|url=https://web.archive.org/web/20090516193335/http://www.astro.caltech.edu/~wws/poss2.html |date=2009-05-16 }}</ref>

Until the completion of the Two Micron All Sky Survey ([[2MASS]]), POSS II was the most extensive wide-field sky survey. When completed, the [[Sloan Digital Sky Survey]] will surpass POSS I and POSS II in depth, although the POSS covers almost 2.5 times more area on the sky.

POSS II also exists in digitized form (that is, the photographic plates were scanned) as part of the [[Digitized Sky Survey]] (DSS).<ref>NASA/Space Telescope Science Institute (STScI).: [http://archive.stsci.edu/dss/ <u>M</u>ultimission <u>A</u>rchive at <u>ST</u>ScI (MAST)]</ref>

===QUEST===
The multi-year POSS projects were followed by the Palomar [[Quasar Equatorial Survey Team]] (QUEST) Variability survey.<ref>Caltech press release: [http://pr.caltech.edu/media/Press_Releases/PR12417.html "New Sky Survey Begins at Palomar Observatory."] {{Webarchive|url=https://web.archive.org/web/20040405033327/http://pr.caltech.edu/media/Press_Releases/PR12417.html |date=2004-04-05 }} July 29, 2003.</ref> This survey yielded results that were used by several projects, including the [[Near-Earth Asteroid Tracking]] project. Another program that used the QUEST results discovered [[90377 Sedna]] on 14 November 2003, and around 40 [[Kuiper belt]] objects. Other programs that share the camera are [[Shri Kulkarni]]'s search for [[Gamma ray burster|gamma-ray bursts]] (this takes advantage of the automated telescope's ability to react as soon as a burst is seen and take a series of snapshots of the fading burst), [[Richard Ellis (astronomer)|Richard Ellis]]'s search for [[supernova]]e to test whether the [[universe's expansion]] is accelerating or not, and [[S. George Djorgovski]]'s [[quasar]] search.

The camera for the Palomar QUEST Survey was a mosaic of 112 [[charge-coupled device]]s (CCDs) covering the whole (4° × 4°) field of view of the Schmidt telescope. At the time it was built, it was the largest CCD mosaic used in an astronomical camera. This instrument was used to produce The Big Picture, the largest astronomical photograph ever produced.<ref>Caltech: [http://bigpicture.caltech.edu/ "The Big Picture"] {{webarchive|url=https://web.archive.org/web/20070204102050/http://bigpicture.caltech.edu/ |date=2007-02-04 }}</ref> The Big Picture is on display at [[Griffith Observatory]].

===Current research===
Current research programs on the 200-inch Hale Telescope cover the range of the observable universe, including studies on near-Earth [[asteroids]], outer [[Solar System]] planets, [[Kuiper Belt]] objects, [[star formation]], [[exoplanets]],<ref>JPL: [http://www.jpl.nasa.gov/news/news.cfm?release=2009-090 "Planet-Hunting Method Succeeds at Last."] {{Webarchive|url=https://web.archive.org/web/20220201162200/https://www.jpl.nasa.gov/news/news.cfm?release=2009-090 |date=2022-02-01 }} May 28, 2009.</ref> [[black holes]] and [[x-ray binaries]], [[supernovae]] and other [[transient astronomy|transient]] source followup, and [[quasars]]/[[Active Galactic Nuclei]].<ref>Caltech: [http://www.palomar.caltech.edu:8000/instruments/p200_calendar.tcl Hale Telescope Observing Runs] {{webarchive|url=https://archive.today/20121212205940/http://www.palomar.caltech.edu:8000/instruments/p200_calendar.tcl |date=2012-12-12 }}</ref>

The 48-inch Samuel Oschin Schmidt Telescope operates robotically, and supports a new [[transient astronomy]] sky survey, the [[Zwicky Transient Facility]] (ZTF).<ref name=":0" />

The 60-inch telescope operates robotically, and supports [[ZTF]] by providing rapid, low-dispersion optical [[spectrometer|spectra]] for initial transient classification using the for-purpose Spectral Energy Distribution Machine (SEDM)<ref>{{Cite journal|url=https://iopscience.iop.org/article/10.1088/1538-3873/aaa53f/pdf|doi=10.1088/1538-3873/aaa53f|title=The SED Machine: A Robotic Spectrograph for Fast Transient Classification|year=2018|last1=Blagorodnova|first1=Nadejda|last2=Neill|first2=James D.|last3=Walters|first3=Richard|last4=Kulkarni|first4=Shrinivas R.|last5=Fremling|first5=Christoffer|last6=Ben-Ami|first6=Sagi|last7=Dekany|first7=Richard G.|last8=Fucik|first8=Jason R.|last9=Konidaris|first9=Nick|last10=Nash|first10=Reston|last11=Ngeow|first11=Chow-Choong|last12=Ofek|first12=Eran O.|last13=Sullivan|first13=Donal O'|last14=Quimby|first14=Robert|last15=Ritter|first15=Andreas|last16=Vyhmeister|first16=Karl E.|journal=Publications of the Astronomical Society of the Pacific|volume=130|issue=985|page=035003|arxiv=1710.02917|bibcode=2018PASP..130c5003B|s2cid=54892690}}</ref> [[integral field spectrograph]].