HARPSN

HARPS-N, or High Accuracy Radial velocity Planet Searcher-North, is a high-resolution, ultra-stable spectrograph designed to measure stellar radial velocities with precision sufficient to detect low-mass exoplanets. It is installed at the Telescopio Nazionale Galileo (TNG) on the island of La Palma in the Canary Islands, serving as the northern counterpart to HARPS, which operates at the ESO 3.6 m telescope in La Silla, Chile. The instrument was built to enable precise planet searches around bright stars and to provide accurate measurements of planetary masses and orbital parameters as part of a coordinated global effort to map exoplanet populations.

HARPS-N uses a fiber-fed design that places the spectrograph in a vacuum chamber with stringent temperature control to achieve long-term stability. Light from target stars is delivered to the spectrograph via optical fibers, and a stable wavelength reference is used for calibration, allowing radial-velocity measurements at the meter-per-second level. The spectrograph covers a broad visible wavelength range and employs a high-resolution echelle configuration to resolve stellar absorption lines.

The project is a collaboration among Italian institutions, including INAF, and international partners, and it builds on the HARPS heritage to extend precision Doppler measurements to the northern sky. Since commissioning in the early 2010s, HARPS-N has contributed to exoplanet surveys, mass determinations for known planets, and studies of stellar activity that affect radial-velocity signals.

See also HARPS.