Editing Palomar Testbed Interferometer

{{Short description|Astronomical instrument in California}}
{{Infobox telescope|location=[[Palomar Mountain]], California, US}}

The '''Palomar Testbed Interferometer''' ('''PTI''') was a [[near infrared]], long-baseline stellar [[interferometer]] located at [[Palomar Observatory]] in north [[San Diego County]], California, United States. It was built by [[Caltech]] and the [[Jet Propulsion Laboratory]] and was intended to serve as a testbed for developing interferometric techniques to be used at the [[Keck Interferometer]]. It began operations in 1995 and achieved routine operations in 1998, producing more than 50 refereed papers in a variety of scientific journals covering topics from high precision [[astrometry]]<ref>{{cite journal |author=M. Shao |title=Differential Astrometry of the 61 Cygni System with the Palomar Testbed Interferometer |journal=Bulletin of the American Astronomical Society |date=1999 |volume=31 | pages=1504 | bibcode=1999AAS...195.8714S |name-list-style=vanc |display-authors=1 |last2=Boden |first2=A. F. |last3=Colavita |first3=M. M. |last4=Lane |first4=B. F. |last5=Lawson |first5=P. R. |collaboration=PTI Collaboration}}</ref> to stellar masses,<ref>{{cite journal |last1=Boden|first1=Andrew F. |last2=Torres|first2=Guillermo |last3=Hummel|first3=Christian A. |title=Testing Stellar Models with an Improved Physical Orbit for 12 Bootis |journal=The Astrophysical Journal |date=1 July 2005 |volume=627 |issue=1 |pages=464–476 |doi=10.1086/430058 |arxiv = astro-ph/0502250 |bibcode=2005ApJ...627..464B|s2cid=834038 }}</ref> stellar diameters and shapes.<ref>{{cite journal |last=van Belle |first=G. T. |author2=Creech-Eakman, M. J. |author3=Hart, A. |title=Supergiant temperatures and linear radii from near-infrared interferometry |journal=[[Monthly Notices of the Royal Astronomical Society]] |date=21 April 2009 |volume=394 |issue=4 |pages=1925–1935 |doi=10.1111/j.1365-2966.2008.14146.x |doi-access=free |bibcode = 2009MNRAS.394.1925V |arxiv = 0811.4239 |s2cid=118372600 }}</ref> PTI concluded operations in 2008 and has since been dismantled.<ref>{{cite web|title=Caltech Astronomy - The Palomar Testbed Interferometer (PTI) |url=http://www.astro.caltech.edu/palomar/about/telescopes/decommissioned.html#pti |publisher=Caltech Astronomy |accessdate=2014-12-09}}</ref>

PTI was notable for being equipped with a "dual-star" system, making it possible to simultaneously 
observe pairs of stars; this cancels some of the atmospheric effects of [[astronomical seeing]] and makes very high precision measurements possible.{{Citation needed|date=January 2012}}

A groundbreaking study with the Palomar Testbed Interferometer revealed that the star [[Altair]] is not spherical, but is rather flattened at the poles due to its high rate of rotation.<ref>{{cite journal |last=van Belle |first=Gerard T. |author2=Ciardi, David R. |author3=Thompson, Robert R. |author4=Akeson, Rachel L. |author5=Lada, Elizabeth A.  |title=Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry |journal=The Astrophysical Journal |date=1 October 2001 |volume=559 |issue=2 |pages=1155–1164 |doi=10.1086/322340 |bibcode = 2001ApJ...559.1155V |s2cid=13969695 }}</ref>

==See also==
* [[List of astronomical interferometers at visible and infrared wavelengths]]
* [[List of observatories]]

==References==
{{reflist}}

==External links==
* [http://nexsci.caltech.edu/missions/Palomar/ Palomar Testbed Interferometer (PTI)] at NASA Exoplanet Science Institute.
* [http://www.astro.caltech.edu/palomar/about/telescopes/decommissioned.html#pti Palomar Testbed Interferometer (PTI)] at Caltech Astronomy.

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[[Category:Telescopes]]
[[Category:Interferometric telescopes]]
[[Category:Palomar Observatory]]

[[de:Palomar-Observatorium#Palomar-Testbed-Interferometer]]