View source for Astronomy:MMT Observatory

{{Short description|Part of the Fred Lawrence Whipple Observatory}}
{{Infobox telescope}}

The '''MMT Observatory''' ('''MMTO''') is an [[Astronomy:Astronomical observatory|astronomical observatory]] on the site of [[Astronomy:Fred Lawrence Whipple Observatory|Fred Lawrence Whipple Observatory]] (IAU observatory code 696). The Whipple observatory complex is located on Mount Hopkins, Arizona, US (55&nbsp;km south of Tucson) in the Santa Rita Mountains. The observatory is operated by the [[Organization:University of Arizona|University of Arizona]] and the Smithsonian Institution, and has a visitor center in nearby Amado, Arizona.
The MMTO is the home of the MMT (formerly Multiple Mirror Telescope), which has a [[Physics:Primary mirror|primary mirror]] 6.5 m in [[Diameter|diameter]]. The name comes from the six smaller mirrors originally used before the single primary mirror was installed in 1998. The primary mirror has a special lightweight honeycomb design made by the [[Organization:University of Arizona|University of Arizona]]'s [[Astronomy:Steward Observatory|Steward Observatory]] Mirror Laboratory.
The MMT is housed in a building which allows the walls and roof around the telescope to be completely rolled back, allowing it to cool down very quickly in order to improve  [[Astronomy:Astronomical seeing|observation]].

== Multiple Mirror Telescope (1979&ndash;1998) ==
[[File:Multi Mirror Telescope in 1981.jpg|alt=A rectangular building about the size of a small apartment block stands on a mountaintop, with a vehicle parked in front of it. The building has a wide opening in its front and top, exposing an internal framework structure that holds and somewhat obscures from view a hexagonal arrangement of six circular primary mirrors. In the background, the sky is hazy, hiding the horizon and most of the terrain below the mountain.|thumb|The MMT in 1981, showing its six primary mirrors]]
The Multiple Mirror Telescope operated between 1979 and 1998 with six honeycombed borosilicate mirrors by [[Company:Corning Inc.|Corning]], each with a diameter of {{convert|72|inch|meters}}, which were donated by the NRO after cancellation of the reconnaissance mission KH-10 (codename DORIAN) based on the [[Organization:Manned Orbiting Laboratory|Manned Orbiting Laboratory]].<ref>{{Cite web |url=http://www.nro.gov/foia/docs/NRO_RRG_v2_2012ed.pdf |title=Archived copy |access-date=2017-01-23 |archive-url=https://web.archive.org/web/20161221154843/http://nro.gov/FOIA/docs/NRO_RRG_v2_2012ed.pdf |archive-date=2016-12-21 |url-status=dead }}</ref> These mirrors were providing the equivalent gathering area of a 4.5-meter telescope, making it the third largest optical telescope in the world at the time of its dedication. It featured ambitious design innovations including its unusual optical design proposed by Aden Meinel, a co-rotating building and an [[Astronomy:Altazimuth mount|altitude-azimuth mount]].

With the exception of the [[Astronomy:BTA-6|Large Altazimuth Telescope]] and William Herschel's [[Astronomy:40-foot telescope|40-foot telescope]], major optical telescopes prior to the MMT used [[Astronomy:Equatorial mount|equatorial mount]]s. The MMT heralded a change in telescope design; all major optical telescopes since the MMT have been built with altitude-azimuth mounts. Several technologies pioneered at the MMT contributed to the success of the subsequent generation of large telescopes. These included: high dynamic-range servos for the [[Astronomy:Altazimuth mount|altitude-azimuth]] mount; highly accurate pointing that eliminated the need for sky charts; co-alignment and co-phasing of multiple telescopes; improvements to optical performance by attention to the
thermal environment of the facility; contributions to vacuum coatings deposition, optics cleaning, and maintenance; and early experiments in co-phased adaptive optics.

== MMT (1998&ndash;present) ==

One of the reasons for its original multiple mirror design was the difficulty of casting large mirrors. One solution to this problem was found by Roger Angel of [[Astronomy:Steward Observatory|Steward Observatory]], of the [[Organization:University of Arizona|University of Arizona]], who [[Astronomy:Spin casting (mirrors)|cast mirrors]] with a honeycomb structure in the interior of a rotating oven. This made it possible to replace the six mirrors with a single 6.5-meter one. The original building and part of the structure could be reused. The new mirror was the first of its size to be cast and polished in the Steward Observatory Mirror Laboratory. The updated MMT, its name no longer an acronym,<ref>{{cite web |url=https://www.mmto.org/node/6 |title=History of the Telescope |publisher=MMT Observatory|accessdate=13 November 2013}}</ref> was rededicated on 20 May 2000.<ref>{{cite web |url=http://cfa-www.harvard.edu/cfa/ep/almanac/0700.htm |title=Trend-setting MMT Rededicated After Major Mirror Transplant |publisher=Harvard-Smithsonian Center for Astrophysics |date=2 July 2000 |accessdate=27 January 2015 |url-status=dead |archiveurl=https://web.archive.org/web/20070311132617/http://cfa-www.harvard.edu/cfa/ep/almanac/0700.htm |archivedate=11 March 2007 }}</ref>

In late 2002, a novel [[Physics:Deformable mirror|deformable]] [[Astronomy:Secondary mirror|secondary mirror]] was added to the telescope.<ref>{{cite web |url=http://uanews.org/story/astronomers-get-ultrasharp-images-large-telescope-arizona |archive-url=https://archive.today/20130705174323/http://uanews.org/story/astronomers-get-ultrasharp-images-large-telescope-arizona |url-status=usurped |archive-date=July 5, 2013 |title=Astronomers Get Ultrasharp Images With Large Telescope in Arizona |publisher=The University of Arizona News |date=3 March 2003 |accessdate=27 January 2015}}</ref> While other [[Astronomy:Adaptive optics|adaptive optics]] designs do their corrections with additional mirrors, minimizing the number of warm surfaces in the light path produces better results in [[Physics:Infrared|infrared]] wavelengths. The MMT AO system contributed to the design of the [[Astronomy:Large Binocular Telescope|Large Binocular Telescope]], which achieved record breaking [[Engineering:Strehl ratio|Strehl ratio]]s with its AO system in 2010.

From 2004 to 2010, approximately 8% of MMT observing time was made accessible to the entire astronomical community via the US [[Organization:National Science Foundation|National Science Foundation]]'s Telescope System Instrumentation Program (TSIP), administered by the [[Astronomy:National Optical Astronomy Observatory|National Optical Astronomy Observatory]] (NOAO).<ref>{{cite web |url=https://www.noao.edu/gateway/mmt/ |title=Community Access to the 6.5-m Telescope of the MMT Observatory |publisher=National Optical Astronomy Observatory |date=26 February 2013 |accessdate=27 January 2015}}</ref><ref>{{cite web |url=http://ast.noao.edu/system/tsip/ |title=Telescope System Instrumentation Program (TSIP) |publisher=National Optical Astronomy Observatory |date=29 July 2011 |accessdate=27 January 2015}}</ref>

== See also ==
* Massive Monolithic Telescope A telescope made from a single piece of glass
* [[Astronomy:List of astronomical observatories|List of astronomical observatories]]
* [[Astronomy:List of largest optical reflecting telescopes|List of largest optical reflecting telescopes]]
* List largest optical telescopes in the continental United States

== References ==
{{Reflist|30em}}

== External links ==
*[http://www.mmto.org/ The MMT Observatory]
*[https://web.archive.org/web/20080515173040/http://mmtao.org/ MMT adaptive optics home page]
*[http://www.cleardarksky.com/c/MtHopkinsAZkey.html?1 Mount Hopkins Clear Sky Clock] Forecast of observing conditions.
*[http://www.cfa.harvard.edu/sao/ Smithsonian Astrophysical Observatory (SAO)]
*[http://www.as.arizona.edu/ University of Arizona's Steward Observatory]

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[[Category:Astronomical observatories in Arizona]]

{{Sourceattribution|MMT Observatory}}