Palomar Testbed Interferometer

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Palomar Testbed Interferometer
Pti aerial photo B.jpg
PTI on Palomar Mountain, next to the Hale Telescope
Location(s)San Diego County, California
Coordinates33°21′26″N 116°51′50″W / 33.3571°N 116.864°W / 33.3571; -116.864Coordinates: 33°21′26″N 116°51′50″W / 33.3571°N 116.864°W / 33.3571; -116.864 Edit this at Wikidata
OrganizationCalifornia Institute of Technology
Jet Propulsion Laboratory Edit this on Wikidata
First lightJuly 1995 Edit this on Wikidata
DecommissionedDecember 2008 Edit this on Wikidata
Telescope styleastronomical interferometer
optical telescope Edit this on Wikidata
Number of telescopesEdit this on Wikidata
Diameter0.4 m (1 ft 4 in) Edit this at Wikidata
Palomar Testbed Interferometer is located in the United States
Palomar Testbed Interferometer
Location of Palomar Testbed Interferometer

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[1] to stellar masses,[2] stellar diameters and shapes.[3] PTI concluded operations in 2008 and has since been dismantled.[4]

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]

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.[5]

See also[edit]


  1. ^ M. Shao, et al. (PTI Collaboration) (1999). "Differential Astrometry of the 61 Cygni System with the Palomar Testbed Interferometer". Bulletin of the American Astronomical Society. 31: 1504. Bibcode:1999AAS...195.8714S.
  2. ^ Boden, Andrew F.; Torres, Guillermo; Hummel, Christian A. (1 July 2005). "Testing Stellar Models with an Improved Physical Orbit for 12 Bootis". The Astrophysical Journal. 627 (1): 464–476. arXiv:astro-ph/0502250. Bibcode:2005ApJ...627..464B. doi:10.1086/430058. S2CID 834038.
  3. ^ van Belle, G. T.; Creech-Eakman, M. J.; Hart, A. (21 April 2009). "Supergiant temperatures and linear radii from near-infrared interferometry". Monthly Notices of the Royal Astronomical Society. 394 (4): 1925–1935. arXiv:0811.4239. Bibcode:2009MNRAS.394.1925V. doi:10.1111/j.1365-2966.2008.14146.x. S2CID 118372600.
  4. ^ "Caltech Astronomy - The Palomar Testbed Interferometer (PTI)". Caltech Astronomy. Retrieved 2014-12-09.
  5. ^ van Belle, Gerard T.; Ciardi, David R.; Thompson, Robert R.; Akeson, Rachel L.; Lada, Elizabeth A. (1 October 2001). "Altair's Oblateness and Rotation Velocity from Long‐Baseline Interferometry". The Astrophysical Journal. 559 (2): 1155–1164. Bibcode:2001ApJ...559.1155V. doi:10.1086/322340. S2CID 13969695.

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