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| Alternative names | Oschin Schmidt, 48in Palomar Schmidt |
|---|---|
| Part of | Palomar Observatory[1] |
| Location(s) | San Diego County,California, Pacific States Region |
| Coordinates | 33°21′29″N116°51′43″W / 33.358194°N 116.861806°W /33.358194; -116.861806 |
| Diameter | 48 in (1.2 m) |
  Location of Samuel Oschin telescope | |
 Related media on Commons | |
TheSamuel Oschin telescope (/ˈɔːʃɪn/), also called theOschin Schmidt, is a 48-inch-aperture (1.22 m)Schmidt camera at thePalomar Observatory in northernSan Diego County, California, United States. It consists of a 49.75-inch (1.264 m)Schmidt corrector plate and a 72-inch (1.8 m) (f/2.5) mirror. The instrument is strictly a camera; there is no provision for an eyepiece to look through it. It originally used 10-inch (25 cm) and 14-inch (36 cm) glassphotographic plates. Since the focal plane is curved, these plates had to be preformed in a special jig before being loaded into the camera.
Construction on the Schmidt telescope began in 1939 and it was completed in 1948. It was named theSamuel Oschin telescope in 1986. Before that it was just called the 48-inch (1.2 m) Schmidt.[2]
In the mid-1980s, the corrector plate was replaced using glass with lesschromatic aberration, producing higher quality images over a broader spectrum.[3]
Between 2000 and 2001, it was converted to use aCCD imager. The corrector plate was recently replaced using glass that is transparent to a wider range of wavelengths.[when?] The telescope was originally hand-guided through one of two 10-inch-aperture (0.25 m)refracting telescopes mounted on either side. The camera is now fully automated and remote-controlled. The data collected are transmitted over theHigh Performance Wireless Research and Education Network (HPWREN). It is programmed and operated primarily fromPasadena, California, with no operator on site, except to open and close the observatory dome.
The first CCD camera installed was theNear-Earth Asteroid Tracking (NEAT) camera, which had three separate 4k×4k sensors arranged in a north–south line with substantial (1°) gaps between them. The total field of view was 3.75 square degrees.
From 2003 to 2007, it was the home of theQuasar Equatorial Survey Team camera. This consisted of 112 CCDs, each 2400×600 pixels (161megapixels total), arranged in four columns of 28 (with gaps between), the largest CCD mosaic used in an astronomical camera at the time.[4][5]
The next camera installed (in 2009) was a 12,288-by-8,192-pixel mosaic (100 megapixel) originally built for theCanada–France–Hawaii Telescope.[6] This had a field of view of 7.8 square degrees, and was used for thePalomar Transient Factory.
In 2017 the telescope became the host of theZwicky Transient Facility. Unlike its predecessors, this was custom designed for the Oschin telescope and its wide field of view, using a 16×6144×6160 CCD array (606 megapixels) with a 47-square-degree field of view.
About half of the large photographic glass plate negatives exposed on the telescope, some 19,000 in all, had been accumulating in the sub-basement of the Robinson building at theCalifornia Institute of Technology since 1949. In 2002, astronomerJean Mueller approachedRichard Ellis, the director of theCaltech Optical Observatories, to volunteer to the task of organizing the Oschin Telescope plate archive. Given the go-ahead, she recruited eleven volunteers from theMount Wilson Observatory Association (MWOA) and theLos Angeles Astronomical Society (LAAS), and the team then spent 13 weekends (more than one thousand hours) poring over the stacks, placing plates in protective sleeves, and packing them in more than 500 boxes that were transported to Palomar.
All of the volunteers were presented with the gift of havingasteroids named after them, compliments ofCarolyn S. Shoemaker:10028 Bonus,12680 Bogdanovich,13914 Galegant,16452 Goldfinger,19173 Virginiaterése,20007 Marybrown,21148 Billramsey,22294 Simmons,27706 Strogen, and29133 Vargas. Mueller was also rewarded with a visit to theKeck Observatory inHawaii.[7]
The Oschin Telescope was responsible for the discovery of90377 Sedna on 2003-11-14 andEris, the "10th Planet" on 2005-01-05 from images taken 2003-10-21. The peculiarType Ia supernovaSN 2002cx was discovered with the Oschin telescope on 2002-05-12, 21 UT.[8] Other discoveries include90482 Orcus (in 2004) and50000 Quaoar (in 2002), both large trans-Neptune objects.
In June 2011 it was reported the telescope discovered 6supernovae located 8 billion light years from Earth whose composition lacks hydrogen. This is different from normal supernovae, and will contribute to the research of star formation.[9]
A new 48-inch-diameter corrector plate was made by Grubb-Parsons in England and installed in the telescope. This new plate produces better images over a wider range of wavelengths than the original.
