HARPS-N is an instrument built for the detection of extrasolar planets through the radial velocity method. This method involves looking for subtle changes in the spectral lines of stars that indicate movement due to an orbiting planet. HARPS-N is the highest precision radial velocity spectrometer ever built, capable of reaching precisions of less than a metre per second, which enables the detection of Earth mass planets. The combination of the two allows both the size and mass of planets to be determined and, therefore, also the density. From this we can find out if the planet is rocky, icy or gaseous.
HARPS-N is on the Telescopio Nazionale Galileo, a 3.58 metre Italian telescope situated on La Palma in the Canary Islands of Spain.
It is a northern hemisphere equivalent to the highly successful HARPS instrument at La Silla Observatory in Chile.
Radial velocity observations are particularly useful for following up planets discovered through the transit method. Being located in the northern hemisphere, allows it to observe planets detected by NASA’s Kepler space telescope, which focused on stars in the Cygnus constellation.
HARPS-N is a collaboration between the Geneva Observatory, the Harvard Smithsonian Center for Astrophysics, St. Andrews University, University of Edinburgh, Queen's University Belfast, the UK Astronomy Technology Centre and the Italian Istituto Nazionale di Astrofisica. The UK Astronomy Technology Centre led the calibration unit, front-end unit and instrument control software.
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