# High Accuracy Radial Velocity Planet Searcher

The High Accuracy Radial Velocity Planet Searcher (HARPS) is a high-precision echelle planet-finding spectrograph installed in 2002 on the ESO's 3.6m telescope at La Silla Observatory in Chile. The first light was achieved in February 2003. HARPS has discovered over 130 exoplanets to date, with the first one in 2004, making it the most successful planet finder behind the Kepler space telescope. It is a second-generation radial-velocity spectrograph, based on experience with the ELODIE and CORALIE instruments.

## Characteristics

The HARPS can attain a precision of 0.97 m/s (3.5 km/h), making it one of only two instruments worldwide with such accuracy. This is due 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 careful attention to mechanical stability: the instrument sits in a vacuum vessel which is temperature-controlled to within 0.01 kelvins. The precision and sensitivity of the instrument is such that it incidentally produced the best available measurement of the thorium spectrum. Planet-detection is in some cases limited by the seismic pulsations of the star observed rather than by limitations of the instrument.
The principal investigator on the HARPS is Michel Mayor who, along with Didier Queloz and Stéphane Udry, have used the instrument to characterize the Gliese 581 planetary system, home to one of the smallest known exoplanets orbiting a normal star, and two super-Earths whose orbits lie in the star's habitable zone.
It was initially used for a survey of one-thousand stars.
Since October 2012 the HARPS spectrograph has the precision to detect a new category of planets: habitable super-Earths. This sensitivity was expected from simulations of stellar intrinsic signals, and actual observations of planetary systems. Currently, the HARPS can detect habitable super-Earth only around low-mass stars as these are more affected by gravitational tug from planets and have habitable zones close to the host star.

## Discoveries

This is an incomplete list of exoplanets discovered by the HARPS. The list is sorted by the date of the discovery's announcement. As of December 2017, the list contains 134 exoplanets.
| HD 330075 b | 10 February 2004 |
| μ Arae c | 25 August 2004 |
| HD 2638 b | 22 March 2005 |
| HD 27894 b | 22 March 2005 |
| HD 63454 b | 22 March 2005 |
| HD 93083 b | 30 March 2005 |
| HD 101930 b | 30 March 2005 |
| Gliese 581 b | 8 September 2005 |
| HD 4308 b | 12 October 2005 |
| HD 212301 b | 25 January 2006 |
| HD 69830 b | 18 May 2006 |
| HD 69830 c | 18 May 2006 |
| HD 69830 d | 18 May 2006 |
| Mu Arae d | 14/18 August 2006 |
| Gliese 674 b | 2 April 2007 |
| HD 100777 b | 6 April 2007 |
| HD 190647 b | 6 April 2007 |
| HD 221287 b | 6 April 2007 |
| Gliese 581 c | 23 April 2007 |
| Gliese 581 d | 23 April 2007 |
| HD 171028 b | 7 August 2007 |
| HD 40307 b | 27 June 2008 |
| HD 40307 c | 27 June 2008 |
| HD 40307 d | 27 June 2008 |
| Gliese 176 b | 4 September 2008 |
| BD-17°63 b | 26 October 2008 |
| HD 20868 b | 26 October 2008 |
| HD 73267 b | 26 October 2008 |
| HD 131664 b | 26 October 2008 |
| HD 145377 b | 26 October 2008 |
| HD 153950 b | 26 October 2008 |
| HD 47186 b | 9 December 2008 |
| HD 47186 c | 9 December 2008 |
| HD 181433 b | 9 December 2009 |
| HD 181433 c | 9 December 2009 |
| HD 181433 d | 9 December 2009 |
| HD 45364 b | 3 February 2009 |
| HD 45364 c | 3 February 2009 |
| Gliese 581 e | 21 April 2009 |
| Gliese 667 Cb | 19 October 2009 |
| BD-08°2823 b | 16 December 2009 |
| BD-08°2823 c | 16 December 2009 |
| HD 5388 b | 16 December 2009 |
| HD 181720 b | 16 December 2009 |
| HD 190984 b | 16 December 2009 |
| HD 125612 c | 29 December 2009 |
| HD 125612 d | 29 December 2009 |
| HD 215497 b | 29 December 2009 |
| HD 215497 c | 29 December 2009 |
| HIP 5158 b | 29 December 2009 |
| HD 85390 b | 5 October 2010 |
| HD 90156 b | 5 October 2010 |
| HD 103197 b | 5 October 2010 |
| HIP 12961 b | 6 December 2010 |
| HD 1690 b | 17 December 2010 |
| HD 25171 b | 17 December 2010 |
| HD 113538 b | 17 December 2010 |
| HD 113538 c | 17 December 2010 |
| HD 217786 b | 17 December 2010 |
| HD 33473 Ab | 17 December 2010 |
| HD 89839 b | 17 December 2010 |
| HD 167677 b | 17 December 2010 |
| HD 10180 b | 23 November 2010 |
| HD 10180 c | 23 November 2010 |
| HD 10180 d | 23 November 2010 |
| HD 10180 e | 23 November 2010 |
| HD 10180 f | 23 November 2010 |
| HD 10180 g | 23 November 2010 |
| HD 10180 h | 23 November 2010 |
| HD 63765 b | 1 July 2011 |
| HD 104067 b | 1 July 2011 |
| HD 125595 b | 1 July 2011 |
| HIP 70849 b | 1 July 2011 |
| HD 137388 b | 8 July 2011 |
| HD 204941 b | 8 July 2011 |
| HD 7199 b | 8 July 2011 |
| HD 7449 b | 8 July 2011 |
| 82 G. Eridani b | 17 August 2011 |
| 82 G. Eridani c | 17 August 2011 |
| 82 G. Eridani d | 17 August 2011 |
| HD 85512 b | 17 August 2011 |
| HR 7722 c | 17 August 2011 |
| HD 1461 c | 12 September 2011 |
| HD 13808 b | 12 September 2011 |
| HD 13808 c | 12 September 2011 |
| HD 20003 b | 12 September 2011 |
| HD 20003 c | 12 September 2011 |
| HD 20781 b | 12 September 2011 |
| HD 20781 c | 12 September 2011 |
| HD 21693 b | 12 September 2011 |
| HD 21693 c | 12 September 2011 |
| HD 31527 b | 12 September 2011 |
| HD 31527 c | 12 September 2011 |
| HD 31527 d | 12 September 2011 |
| HD 38858 b | 12 September 2011 |
| HD 39194 b | 12 September 2011 |
| HD 39194 c | 12 September 2011 |
| HD 39194 d | 12 September 2011 |
| HD 45184 b | 12 September 2011 |
| HD 51608 b | 12 September 2011 |
| HD 51608 c | 12 September 2011 |
| HD 93385 b | 12 September 2011 |
| HD 93385 c | 12 September 2011 |
| HD 96700 b | 12 September 2011 |
| HD 96700 c | 12 September 2011 |
| HD 126525 b | 12 September 2011 |
| HD 134060 b | 12 September 2011 |
| HD 134060 c | 12 September 2011 |
| HD 134606 b | 12 September 2011 |
| HD 134606 c | 12 September 2011 |
| HD 134606 d | 12 September 2011 |
| ν$^2$ Lupi b | 12 September 2011 |
| ν$^2$ Lupi c | 12 September 2011 |
| ν$^2$ Lupi d | 12 September 2011 |
| HD 150433 b | 12 September 2011 |
| HD 154088 b | 12 September 2011 |
| HD 157172 b | 12 September 2011 |
| HD 189567 b | 12 September 2011 |
| HD 204313 c | 12 September 2011 |
| HD 215152 b | 12 September 2011 |
| HD 215152 c | 12 September 2011 |
| HD 215456 b | 12 September 2011 |
| HD 215456 c | 12 September 2011 |
| Gliese 667 Cc | 21 November 2011 |
| HD 10180 i | 5 April 2012 |
| HD 10180 j | 5 April 2012 |
| GJ 3470 b | 22 June 2012 |
| Gliese 676 c | 29 June 2012 |
| Gliese 676 d | 29 June 2012 |
| Gliese 676 e | 29 June 2012 |
| Gliese 163 b | 6 September 2012 |
| Gliese 163 c | 6 September 2012 |
| Gliese 667 Cd | 25 June 2013 |
| Gliese 667 Cg | 25 June 2013 |

## Gallery

* HELIOS instrument installed to feed sunlight via fibre optics to the HARPS
* A decade of discoveries from HARPS
* HARPS spectrograph
* HARPS spectrograph detail
* Animation of HD 10180 with its seven planets