Telescope & Instruments

HARPS-North - High Accuracy Radial velocity Planet Searcher


Instrument Description

HARPS-N is an echelle spectrograph covering the wavelength range between 383 to 693 nm, with a spectral resolution R=115000. This instrument allows the measurement of radial velocities with the highest accuracy currently available in the north hemisphere and is designed to avoid spectral drift due to temperature and air pressure variations thanks to a very accurate control of pressure and temperature. HARPS-N is fibre-fed by the Nasmyth B Focus of the 3.6 TNG telescope through a Front End Unit (FEU). The two HARPS fibres (object + sky or Th-Ar) have an aperture on the sky of 1"; this produces a resolving power of 115,000 in the spectrograph. Both fibres are equipped with an image scrambler to provide a uniform spectrograph pupil illumination, independent of pointing decentering.
The main scientific rationale of HARPS-N is the characterization and discovery of terrestrial planets by combining transits and Doppler measurements.
The HARPS-N Project is a collaboration between the Astronomical Observatory of the Geneva University (lead), the CfA in Cambridge, the Universities of St. Andrews and Edinburgh, the Queens University of Belfast, and the TNG-INAF Observatory.

Spectrograph typeFiber fed, cross-disperser echelle spectrograph
Spectral resolution R= 115’000
Fiber fieldFOV = 1”
Wavelength range383 nm - 690 nm
Total efficiencye = 8 % @ 550 nm (incl. telescope and atmosphere @ 0.8" seeing)
Samplings = 3.3 px per FWHM
CalibrationThAr + Simultaneous reference (fed by 2 fibers)
CCDBack illuminated CCD 4k4 E2V chips (graded coating)
Pixel size15 µm
EnvironmentVacuum operation - 0.001 K temperature stability
Global short-term precision0.3 m/s (10E-9)
Global long-term precisionbetter than 0.6 m/s (2x10E-9)
Observational efficiencySNR = 50 per extracted pixel on a Mv=8 in 1 minute exposure
Wavelength accuracy60 m/s (2x10E-7) on a single line

Instrument Status

7 January 2012First light in laboratory (image)
16 January 2012Start install thermal Enclosure
5 February 2012Instrument shipped to TNG
5 March 2012Install FEU and Cal unit on Telescope & Engineering
25 March 2012Harps-N first light
27 March 2012Harps-Nature
22 April 2012Science Team meeting in La Palma
23 April 2012Official HARPS-N inauguration
13 February 2013Software upgrade, big changes implemented
05 March 2013 HARPSN warming up and full enclosure added
22 March 2013 CCD controller changed
23 April 2013 The flux of the lamp Th2 had increased by a factor 1.8
14 January 2014Software upgrade: Sequencer, Exposure meter and focus procedure
22 March 2014Focus of the spectrograph was improved by opening the vacuum vessel and readjusting the fiber entrance.
22 March 2014Realignement the exposure meter
22 March 2014Contamination of the calibration frames was solved
22 March 2014Improvement to the LCU and AG software to avoid 'AXIS failed' situations that require re.init of the CU module in the LCU.
22 March 2014Broken Fabry-Pérot LDLS lamp was replaced and FP re-aligned.
22 March 2014Fixed the random error in writing the G-HARPN file (autoguide)
22 March 2014The LN2 tank was equipped with a metallic filter at the entrance of the tube to avoid migration into the CFC of metal cristal. Pressure was increased from 0.4 to 0.8 mbar for some spare flux
18 June 2014Periodic warm up of the CCD due to CFC contamination
20 August 2014Repair of problem with failing TUNA
17 October 2014We put back the fiber head to the FEU after the maintenance work to the derotator B. We tested the alignment and reestablished the previous conditions
17 October 2014Periodic warm up of the CCD due to CFC contamination
07 November 2014The flux of the lamp ThAr2 was decreased by a factor 2 and the flux of the ThAr1 was decreased about 20%
03 February 2015Periodic warm up of the CCD due to CFC contamination
19 February 2015Periodic warm up of the CCD due to CFC contamination
23 February 2015Periodic warm up of the CCD due to CFC contamination
24 February 2015Increase of the CCD temperature due to a malfunction of dosing valve
19 May 2015Scheduled washing of the CFC line, warm up of the CCD
15 September 2015We changed the thar2 lamp because the flux changed very fast
23 September 2015We increased the flux of the ThAr2 lamp by a factor of 1.5
13 October 2015Fabry Perot tuning (Francois Wildi) - FP=4.4 Cm/sec / Thar=5.3 Cm/sec
13 October 2015Scheduled washing of the CFC line, warm up of the CCD
15 October 2015Disconnected the “Arduino” used to monitor the cold plate temperature
24 February 2016Software upgrade: Sequencer (change the ADCs on/off sequence)
24 February 2016Software upgrade: LCU telemetry (Added unit and some parameter)
14 March 2016Decreased the flux of the ThAr2 lamp
31 March 2016Scheduled washing of the CFC line, warm up of the CCD
14 April 2016Software upgrade (LCU): the elevation threshold used for the ADCs movements now is hard-coded because the compilated version in unable to read the configuration correctly.
19 April 2016Changed the threshold of DRS configuration file: qc_dev_littrow_max B to [0.300,0.300,0.300] and qc_rms_littrow_max B to [0.006,0.006,0.006]
15 June 2016Set the Thorium A as reference in both fibers in HARPN-ech-cal-thoAB template
25 August 2016Added the HIERARCH TNG INS LCU ADC1 and HIERARCH TNG INS LCU ADC2 keywords to the fits files
03 October 2017Software upgrade (LCU): New LCU interface installed together with a new version of the sequencer

GTO Protected Targets

In force of the agreement between the Consortium and INAF the instrument is located at the TNG for a period of 5 years. INAF can use the instrument without limitation during the period of the agreement in change of an amount of 80 nights per year of Guaranteed Time of Observation. The Consortium decided to use the GTO for:

  1. The follow-up of Kepler planets candidates
  2. The search of nearby rocky planets.

INAF-TNG is committed to protect the targets for exclusive observation with Harps-N within the Consortium.
Therefore, targets in the protected list cannot be allowed in any proposal from any user.
The list can be found at this link:

The follow-up of Kepler planets candidates
The search of nearby rocky planets

The search of nearby rocky planets

Contact Information

Instrument Scientist: Rosario Cosentino


The instrument Harps-N is owned by the construction partners in a share proportional to their contribution in human and financial resources.
The Consortium is managed by an Executive Board, which is composed by one member per country, plus the Principal Investigator.
A Science Team is the body who decides the scientific use of the instrument during the GTO time and propose collaborators to the project, which are then approved by the Executive Board.

Geneva Observatory (Geneva University)
CfA and Harvard University
University of St. Andrews, Edinburgh, and Belfast

Executive Board

Francesco Pepe (PI)Observatoire de l'Université de Genève, CH
Stephane UdryObservatoire de l'Université de Genève, CH
Dave LathamCenter for Astrophysics, Cambridge USA
Andrew Collier-CameronUniversity of St. Andrews, UK
Emilio MolinariINAF-Telescopio Nazionale Galileo, Italy

Science Team

Italy Alessandro Sozzetti, Osservatorio Astronomico Torino
Giampaolo Piotto, Dipartimento di Astronomia, Università di Padova
Giusi Micela, Osservatorio Astronomico Palermo
Switzerland Francesco Pepe, Observatoire Astronomique de l'Université de Genève
Stéphane Udry, Observatoire Astronomique de l'Université de Genève
Michel Mayor, Observatoire Astronomique de l'Université de Genève
François Bouchy, Observatoire Astronomique de l'Université de Genève
Damien Ségransan, Observatoire Astronomique de l'Université de Genève
Christopher Lovis, Observatoire Astronomique de l'Université de Genève
UK Andrew Collier Cameron, School of Physics & Astronomy , University of St Andrews
Don Pollacco, Queen's University Belfast
Ken Rice, Edinburgh University Institute for Astronomy
USA Dave Latham, Harvard-Smithsonian Center for Astrophysics
Dave Charbonneau, Harvard-Smithsonian Center for Astrophysics
Dimitar Sasselov, Harvard-Smithsonian Center for Astrophysics
Andrew Szentgyorgyi, Harvard-Smithsonian Center for Astrophysics
David Phillips, Harvard-Smithsonian Center for Astrophysics
Mercedes Lopez-Morales, Harvard-Smithsonian Center for Astrophysics

Collaborating Institutes


HARPS-N Data Reduction Pipeline

The HARPS pipeline is able to supply online science quality extracted spectra and radial velocities (RV) for solar type stars exploiting the full precision of the instrument.

The spectral extraction is performed using the classical optimal extraction method by Horne (Horne, K. 1986, PASP, 98, 609). The basic processing steps consist in the order, in bias subtraction (the bias is computed on the overscan regions of the frame), spectrum extraction, flat fielding, wavelength calibration and if requested, the cross correlation computation.

HARPS-N Archive

Scientific data collected are automatically saved in the TNG archive and copied to the IA2 Archive facility where the astronomers can download their own data. The GTO data are private and follow the rule defined by the consortium.

HARPS-N Observing tools