The High Accuracy Radial velocity Planet Searcher (HARPS) is a high-precision echelle spectrograph installed in 2002 on ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. It is a second-generation radial-velocity spectrograph, based on experience with the ELODIE and CORALIE instruments.[1]
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HARPS can attain a precision of 0.97 m/s (3.5 km/h),[2] with an effective precision of the order of 30 cms-1,[3] making it one of only two instruments worldwide with such accuracy. This is thanks to a design in which the target star and a reference spectrum from a thorium lamp are observed simultaneously using two identical optic fibre feeds, and to very great attention to mechanical stability: the instrument sits in a vacuum vessel which is temperature-controlled to within 0.01 °K[4]. The precision and sensitivity of the instrument is such that it incidentally produced the best available measurement of the thorium spectrum.[1] Planet-detection is in some cases limited by the seismic pulsations of the star observed rather than by limitations of the instrument.[5]
The principal investigator on HARPS is Michel Mayor who, along with Didier Queloz and Stéphane Udry have used the instrument to characterize the Gliese 581 system, home to the smallest known exoplanet orbiting a normal star, and two super-Earths whose orbits lie in the star's habitable zone.[6]
It was initially used for a survey of a thousand stars.
This instrument has been used to discover 16 planetary objects in the southern hemisphere, including four multi-planet systems, as of May 2009.
| Planet | Date announced |
|---|---|
| HD 330075 b | 10 February 2004 |
| Mu Arae c | 25 August 2004 |
| Gliese 876 d | 13 June 2005 |
| HD 93083 b | 2005 |
| HD 101930 b | 2005 |
| HD 102117 b | 2005 |
| HD 4308 b | 2005 |
| HD 69830 b | 18 May 2006 |
| HD 69830 c | 18 May 2006 |
| HD 69830 d | 18 May 2006 |
| Gliese 581 c | 23 April 2007 |
| Gliese 581 d | 23 April 2007 |
| HD 40307 b | June 2008 |
| HD 40307 c | June 2008 |
| HD 40307 d | June 2008 |
| Gliese 581 e | April 2009 |
In October 2009, the discovery of 32 additional exoplanets was announced by ESO,[7] bringing the total to 75 exoplanets first observed by HARPS.[2]
In August 2010, the discovery of several exoplanets was announced, including HD 10180.
In September 2011, it was announced that 50 planets were discovered, including Super-Earths, in particular, HD 85512 b, which lies just on the edge of the habitable zone.
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