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Caltech Submillimeter Observatory

TheCaltech Submillimeter Observatory(CSO) was a 10.4-meter (34 ft) diameter submillimeter wavelengthtelescopesituated alongside the 15-meter (49 ft)James Clerk Maxwell Telescope(JCMT) atMauna Kea Observatories.Beginning in 1986, it was engaged insubmillimeter astronomyof theterahertz radiationband. The telescope closed on September 18, 2015.[1]

Caltech Submillimeter Observatory
Location(s)Hawaii County,Hawaii
Coordinates19°49′21″N155°28′34″W/ 19.8225°N 155.476°W/19.8225; -155.476Edit this at Wikidata
OrganizationCalifornia Institute of TechnologyEdit this on Wikidata
Altitude13,570 ft (4,140 m)Edit this at Wikidata
Wavelength1,300, 350, 850 μm (230, 860, 350 GHz)
Built–1985(–1985)Edit this at Wikidata
First light1986Edit this on Wikidata
Decommissioned2015Edit this on Wikidata
Telescope styleobservatory
radio telescopeEdit this on Wikidata
Diameter10.4 m (34 ft 1 in)Edit this at Wikidata
Websitewww.submm.caltech.edu/cso/Edit this at Wikidata
Caltech Submillimeter Observatory is located in Hawaii
Caltech Submillimeter Observatory
Location of Caltech Submillimeter Observatory
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Disassembly of theCaltechSubmillimeter Observatory's (CSO) 34-foot diameter telescope on Maunakea began the week of August 28, 2023. The entire remediation process is expected to be completed by summer 2024 and cost more than $4 million. CSO is the first observatory to be removed under the Decommissioning Plan of the University of Hawaiʻi Maunakea Comprehensive Management Plan.

History

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In 1973Robert Leightonproposed to theNSFto build four 10.4 meter diameter parabolic dish radio antennas. Three of theseLeighton antennaswere to be used as a mm-wave interferometer to be sited atOVRO,and the fourth was to be used as a single submillimeter telescope at a high mountain site. The proposal was approved (AST 73-04908[2]), but the NSF insisted that the mm-wave array had to be completed before work on the submillimeter telescope could be started, which delayed the construction of the submillimeter telescope by almost a decade. Mauna Kea was selected as the site for the submillimeter telescope, which became the Caltech Submillimeter Observatory, after a site survey byThomas G. Phillips.[3]The three antenna mm-wave interferometer at OVRO was eventually expanded to six elements, and ultimately became part of theCARMAarray in California'sInyo Mountains.

The CSO antenna, named the Leighton Telescope after the death of Robert Leighton in 1997, has a more precise surface than the CARMA array antennas, enabling it to make use of the superior Mauna Kea site by operating at higher frequencies. Heating elements were also added to the stand-off pins which support the hexagonal panels, to allow active control of the surface.[4]

Before being deployed to Hawaii, both the antenna (without its dish) and the dome building were assembled on the Caltech campus, at the current site of theIPACbuilding, in order to ensure that the building and its shutter operated correctly. Despite having assembled the building once on the Caltech campus, the construction contractor had difficulty re-assembling the building in the high altitude environment of Mauna Kea, and the contractor went bankrupt. After the bankruptcy Caltech staff had to supervise completion of the observatory construction.

Operation

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TheHorsehead Nebula,as seen in visible light on the left, and on the right as a false color image made from data taken at the CSO, of the intensity of the 230 GHz rotational transition of carbon monoxide.

Throughout its nearly three decade operational lifetime, the CSO was funded primarily by the NSF. TheUniversity of Texasprovided additional funding from the start of 1988 through the end of 2012.

The CSO emphasizedheterodyne receiverwork, while the neighboringJames Clerk Maxwell Telescopeemphasized continuum detector observations. Most of the heterodyne receivers were built on the Caltech campus, and were placed at theNasmyth focus.The University of Texas team built instruments for the CSO, including a re-imaging system which effectively converted the 10.4 meter telescope into a 1 meter off-axis telescope with a 3 arc minute wide beam at 492 GHz. This wide beam system was used to map the atomic carbon line at 492 GHz over large regions of the sky.[5]The UT team also provided an 850 GHz receiver for the telescope'sCassegrain focus.

In 1986, the CSO obtained official "first light" by producing a spectrum of thecarbon monoxideJ=2-1 line from the nearbystarburst galaxyMessier 82(although continuum detections of the Moon and some planets had been made earlier).

The CSO and JCMT were combined to form the first submillimeterinterferometer.[6]The success of this experiment was important in pushing ahead the construction of theSubmillimeter Arrayand theAtacama Large Millimeter Arrayinterferometers. The CSO was also a part of theEvent Horizon Telescopearray during the early test observations which proved the feasibility of intercontinental mm-wave interferometry.

Research Highlights:

  • The first detection of theSunyaev-Zel'dovich Effectat millimeter wavelengths, and the first measurement of cluster temperature using the Sunyaev-Zel'dovich Effect.[7][8]
  • TheBolocam Galactic Plane Survey,a survey of continuum emission at 1.1 mm, which covered 170 square degrees of the galactic plane. This survey resulted in the publication of at least 14 journal papers with over 1000 aggregate citations.[9]
  • Discovery of new submillimeter watermaserspectral lines at 321, 325, 437, 439, 471, and 658 GHz.[10][11][12][13]
  • Molecular line surveys in the submillimeter band of the star formation regionsSagittarius B2andOrion KL;the carbon starIRC+10216;and the planets Jupiter and Saturn.[14][15][16][17][18]
  • Discovery of a ~200 km/sec fast molecular wind from theprotoplanetary nebulaCRL 618.This fast neutral wind will interact with the slowAGBwind to shape the finalplanetary nebula.[19]
  • Submillimeter observations of theSolar eclipse of July 11, 1991,a very unusual eclipse in that it passed over several major observatories.[20]Observing the Sun would normally have constituted a severe violation of the telescope's sun-avoidance limits, as it was normally forbidden to allow any sunlight to fall upon even a portion of the telescope's primary mirror. However for this special event a tent-like membrane was deployed over the dish, which prevented focused visible and infrared light from destroying the secondary mirror assembly.

The last observation from the telescope was made on 8 September 2015, and was ofOrion KL.[21]

Over 100 students from 25 institutions used the CSO for doctoral research projects.[22]

Decommissioning

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Caltech Submillimeter Observatory.

In order to get a permit to build theThirty Meter Telescopeproject on Mauna Kea, theUniversity of Hawaiihad to commit to closing and dismantling three existing observatories on the mountain. The three chosen were the CSO, theUKIRT,and the Hoku Keʻa telescope.[1]Two additional telescopes must also be removed by 2033, but those have not been selected as of 1 April 2019.[23]

On April 30, 2009, Caltech announced plans to decommission the CSO, transferring ongoing research to the next-generationCerro Chajnantor Atacama Telescope(CCAT) in Chile. The plans called for CSO to be dismantled, beginning in 2016, with its site returned to a natural state by 2018.[24]Delaysin the environmental assessment and permitting processes have led to postponement of the telescope removal.[23]

The CSO site after the telescope and dome were removed, and the site was restored.

Disassembly of the Caltech Submillimeter Observatory's (CSO) 34-foot diameter telescope on Maunakea began the week of August 28, 2023. The entire decommissioning process was completed in July 2024[25]and cost more than $4 million. CSO was the first observatory to be removed under the Decommissioning Plan of the University of Hawaiʻi Maunakea Comprehensive Management Plan.[26][27]

See also

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References

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  1. ^ab"Third Maunakea observatory set for decommissioning".University of Hawaii News.University of Hawaii. October 21, 2015.RetrievedDecember 3,2015.
  2. ^Leighton, Robert B."Final Technical Report"(PDF).Caltech Library.RetrievedOctober 31,2020.
  3. ^Phillips, T. G. (June 2007)."The Caltech Submillimeter Observatory".2007 IEEE/MTT-S International Microwave Symposium.pp. 1849–1852.Bibcode:2007ims..confE...1P.doi:10.1109/MWSYM.2007.380111.ISBN978-1-4244-0687-6.S2CID1708648.RetrievedOctober 30,2020.
  4. ^Leong, Melanie; Peng, Ruisheng; Yoshida, Hiroshige; Chamberlin, Richard; Phillips, Thomas G. (2009). "A Caltech Submillimeter Observatory Active Optics System".Submillimeter Astrophysics and Technology: A Symposium Honoring Thomas G. Phillips.ASP Conference Series. Vol. 417. pp. 131–135.ISBN978-1-58381-714-8.RetrievedOctober 30,2020.
  5. ^Plume, Rene; Jaffe, Daniel T. (May 1995)."The World's Smallest 10-meter Submillimeter Telescope".Publications of the Astronomical Society of the Pacific.107:488–495.Bibcode:1995PASP..107..488P.doi:10.1086/133579.S2CID120255254.RetrievedNovember 19,2020.
  6. ^Carlstrom, John; Hills, Richard; Lay, Oliver; Force, Brian; Hall, C. G.; Phillips, Thomas; Schinckel, Antony (1994).The CSO-JCMT Submillimeter Interferometer(PDF)(ASP Conference Series, Vol 59 ed.). Cambridge University Press. pp. 35–40.ISBN0-937707-78-3.RetrievedMarch 18,2024.
  7. ^Wilbanks, T. M.; Ade, P. A. R.; Fischer, M. L.; Holzapfel, W. L.; Lange, A. E. (June 1994)."Measurement of the Sunyaev-Zel'dovich Effect toward Abell 2163 at a Wavelength of 2.2 Millimeters".Astrophysical Journal Letters.427:L75–L78.Bibcode:1994ApJ...427L..75W.doi:10.1086/187368.RetrievedOctober 31,2020.
  8. ^Hansen, Steen H.; Pastor, Sergio; Semikoz, Dmitry V. (July 2002)."First Measurement of Cluster Temperature Using the Thermal Sunyaev-Zel'dovich Effect".Astrophysical Journal Letters.573(2): L69–L71.arXiv:astro-ph/0205295.Bibcode:2002ApJ...573L..69H.doi:10.1086/342094.S2CID6540903.RetrievedOctober 31,2020.
  9. ^Aguirre, James E.; Ginsburg, Adam G.; Dunham, Miranda K.; Drosback, Meredith M.; Bally, John; Battersby, Cara; Bradley, Eric Todd; Cyganowski, Claudia; Dowell, Darren; Evans, Neal J.; Glenn, Jason; Harvey, Paul; Rosolowsky, Erik; Stringfellow, Guy S.; Walawender, Josh; Williams, Jonathan P. (January 2011)."The Bolocam Galactic Plane Survey: Survey Description and Data Reduction".Astrophysical Journal Supplement Series.192(1): 4.arXiv:1011.0691.Bibcode:2011ApJS..192....4A.doi:10.1088/0067-0049/192/1/4.hdl:2152/42997.S2CID119275808.RetrievedNovember 6,2020.
  10. ^Menten, K. M.; Melnick, G. J.; Phillips, T. G. (1990)."Submillimeter Water Masers".Astrophysical Journal Letters.350:L41–L44.Bibcode:1990ApJ...350L..41M.doi:10.1086/185663.RetrievedNovember 6,2020.
  11. ^Menten, K. M.; Melnick, G. J.; Phillips, T. G.; Neufeld, D. A. (1990)."A New Submillimeter Water Maser Transition at 325 GHz".Astrophysical Journal Letters.363:L27–L31.Bibcode:1990ApJ...363L..27M.doi:10.1086/185857.RetrievedOctober 31,2020.
  12. ^Menten, K. M.; Young, K. (1995)."Discovery of Strong Vibrationally Excited Water Masers at 658 GHz Toward Evolved Stars".Astrophysical Journal Letters.450:L67–L70.Bibcode:1995ApJ...450L..67M.doi:10.1086/316776.RetrievedOctober 31,2020.
  13. ^Melnick, Gary J.; Menten, Karl M.; Phillips, Thomas G.; Hunter, Todd (October 1993)."Discovery of Interstellar Water Lines at 437, 439, and 471 GHz: Strong Case for Water Maser Formation behind C-Type Shocks".Astrophysical Journal Letters.416:L37–L40.Bibcode:1993ApJ...416L..37M.doi:10.1086/187065.RetrievedOctober 31,2020.
  14. ^Sutton, E. C.; Jaminet, P. A.; Danchi, W. C.; Blake, Geoffrey A. (October 1991)."Molecular Line Survey of Sagittarius B2(M) from 330 to 355 GHz and Comparison with Sagittarius B2(N)".Astrophysical Journal Supplement Series.77:255–285.Bibcode:1991ApJS...77..255S.doi:10.1086/191603.RetrievedOctober 31,2020.
  15. ^Groesbeck, T. D.; Phillips, T. G.; Blake, Geoffrey A. (1994)."The Molecular Emission-Line Spectrum of IRC +10216 between 330 and 358 GHz".Astrophysical Journal Supplement Series.94(1): 147–162.Bibcode:1994ApJS...94..147G.doi:10.1086/192076.PMID11539132.RetrievedOctober 31,2020.
  16. ^Weisstein, Eric W.; Serabyn, E. (September 1996)."Submillimeter Line Search in Jupiter and Saturn".Icarus.123(1): 23–36.Bibcode:1996Icar..123...23W.doi:10.1006/icar.1996.0139.RetrievedOctober 31,2020.
  17. ^Schilke, P.; Groesbecj, T. D.; Blake, G. A.; Phillips, T. G. (January 1997)."A Line Survey of Orion KL from 325 to 360 GHz".Astrophysical Journal Supplement Series.108(1): 301–337.Bibcode:1997ApJS..108..301S.doi:10.1086/312948.PMID11539874.S2CID5940584.RetrievedOctober 31,2020.
  18. ^Schilke, P.; Benford, D. J.; Hunter, T. R.; Lis, D. C.; Phillips, T. G. (February 2001)."A Line Survey of Orion-KL from 607 to 725 GHZ".Astrophysical Journal Supplement Series.132(2): 281–364.Bibcode:2001ApJS..132..281S.doi:10.1086/318951.S2CID123133670.RetrievedOctober 31,2020.
  19. ^Gammie, C. F.; Knapp, G. R.; Young, K.; Phillips, T.G.; Falgarone, E. (1989)."A Very Fast Molecular Outflow from the Protoplanetary Nebula CRL 618".Astrophysical Journal Letters.345:L87–L89.Bibcode:1989ApJ...345L..87G.doi:10.1086/185559.RetrievedOctober 31,2020.
  20. ^Ewell, M. W. Jr; Zirin, H.; Jensen, J. B.; Bastian, T. S. (January 1993)."Submillimeter Observations of the 1991 July 11 Total Solar Eclipse".Astrophysical Journal.403:426–433.Bibcode:1993ApJ...403..426E.doi:10.1086/172213.RetrievedOctober 31,2020.
  21. ^McGuire, Brett A.; Carroll, P. Brandon (October 31, 2017)."The Final Integrations of the Caltech Submillimeter Observatory".Research Notes of the AAS.1(1): 4.arXiv:1711.09145.Bibcode:2017RNAAS...1....4M.doi:10.3847/2515-5172/aa9657.ISSN2515-5172.S2CID119348746.
  22. ^"Overview [CSO Wiki]".
  23. ^ab"VIDEO: Update On Taking Telescopes Off Mauna Kea".bigislandvideonews.RetrievedApril 2,2019.
  24. ^"Caltech Submillimeter Observatory in Hawaii to be Decommissioned"(Press release). Caltech.edu. April 30, 2009. Archived fromthe originalon June 10, 2010.RetrievedDecember 22,2010.
  25. ^Haggerty, Noah (August 2, 2024)."Caltech observatory atop Hawaii's Mauna Kea, a source of cultural tension, is dismantled".Los Angeles Times.RetrievedAugust 13,2024.
  26. ^"Removal of Caltech Telescope from Maunakea is underway".University of Hawaiʻi System News.August 28, 2023.RetrievedDecember 22,2023.
  27. ^"Telescope removed from Caltech Submillimeter Observatory atop Maunakea; decommissioning paused until spring".Big Island Now.December 21, 2023.RetrievedDecember 22,2023.
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