NANTEN2

NANTEN2
Name	NANTEN2
Organization	Nagoya University; University of Cologne; Osaka Prefecture University; University of Bonn; University of Chile
Location	Pampa la Bola, Atacama, Chile
Altitude	4800 m
Established	2004 (relocation 2005)
Telescope type	Submillimeter radio telescope
Diameter	4 m
Wavelength	0.3–3 mm

NANTEN2 NANTEN2 is a 4‑metre submillimetre radio telescope dedicated to millimetre and submillimetre astronomy, operated by an international consortium involving institutions such as Nagoya University, Max Planck Society, University of Cologne, Osaka Prefecture University, and University of Chile. Located on the Pampa la Bola plateau in the Atacama Desert of northern Chile, NANTEN2 has been a key facility for studies of molecular clouds, star formation, and the interstellar medium, contributing to work connected with facilities like ALMA, APEX, and IRAM. The project built on heritage from the original NANTEN telescope in Las Campanas Observatory and interfaces with programs by agencies including the National Astronomical Observatory of Japan, European Southern Observatory, and the National Science Foundation.

Overview

The instrument originated from a collaboration initiated by groups at Nagoya University, University of Tokyo, and the Institute of Space and Astronautical Science with later partners such as the University of Bonn and Max Planck Institute for Radio Astronomy. The telescope was relocated from Las Campanas Observatory to the high Andes near San Pedro de Atacama to exploit the dry atmosphere above altitudes similar to those used by ALMA and Chajnantor Plateau projects. NANTEN2 has operated within observational frameworks alongside missions like Herschel Space Observatory, Planck, and ground arrays like SMA, enabling cross‑comparisons with data from facilities including JCMT, SOFIA, and Spitzer Space Telescope.

Telescope and Instrumentation

The 4‑metre antenna and its Nasmyth optics support heterodyne receivers and bolometer arrays developed at institutions such as Nagoya University, University of Cologne, KOSMA, and Max Planck Institute for Astronomy. Key hardware included SIS mixers and Schottky receivers covering bands overlapping with instruments on IRAM 30m, Onsala Space Observatory telescopes, and the Nobeyama Radio Observatory. Backend spectrometers used autocorrelators and digital FFT spectrometers similar to units deployed at ALMA and NOEMA; calibration and pointing systems were informed by standards established at VLA and GBT. Cryogenic systems were supplied and maintained with support from JAXA and partner laboratories such as RIKEN and CITA.

Observational Programs and Surveys

NANTEN2 performed large‑scale molecular surveys of the Milky Way and nearby galaxies, mapping CO isotopologues and atomic carbon lines in targets including the Carina Nebula, Orion Molecular Cloud, Taurus Molecular Cloud, Rho Ophiuchi Cloud Complex, Magellanic Clouds, Large Magellanic Cloud, and Small Magellanic Cloud. Survey strategies paralleled campaigns by FCRAO, CfA, and Mopra Telescope groups, and complemented spectral line programs by ASTE and NANTEN teams. Time was allocated to projects on galactic center chemistry in the vicinity of Sagittarius A*, extragalactic star formation in M83, NGC 253, and feedback studies in regions such as 30 Doradus.

Science Results

Science outputs addressed the lifecycle of molecular gas, the role of turbulence and magnetic fields in star formation, and the excitation of carbon and oxygen fine‑structure lines. Results included measurements of CO excitation ladders that informed models used by researchers at Princeton University, Harvard–Smithsonian Center for Astrophysics, and Caltech. NANTEN2 observations contributed to determinations of the CO‑to‑H2 conversion factor used by teams at University of California, Berkeley and Max Planck Institute for Extraterrestrial Physics, and to studies of photon‑dominated regions comparable to work by groups at University of Leiden and University of Maryland. Cross‑calibration with Herschel and Planck data improved constraints on dust continuum emission modeled by investigators at Imperial College London and University College London.

Collaborations and Operations

Operations involved consortia across Asia, Europe, and South America, including partners such as Nagoya University, University of Cologne, University of Bonn, University of Chile, and the National Astronomical Observatory of Japan. The project organized joint observing campaigns with ALMA Regional Center nodes and shared data products with archives used by NASA, ESA, and national data centers like NAOJ. Training programs and student projects linked to universities including Kyoto University, Osaka University, Hokkaido University, and Pontifical Catholic University of Chile fostered international exchange similar to collaborations seen in projects run by ESO and CERN.

Site and Facilities

The site on the Pampa la Bola plateau, at elevations comparable to the Chajnantor Plateau, offers low precipitable water vapor and sky conditions exploited by instruments such as ALMA, APEX, and ASTE. Support infrastructure included access roads from Calama, logistics coordination with municipalities like San Pedro de Atacama, and maintenance partnerships with regional facilities at Cerro Tololo Inter-American Observatory. Environmental and cultural consultations involved stakeholders including Chilean authorities and academic partners analogous to processes used for Paranal Observatory and Las Campanas Observatory developments.

Category:Radio telescopes Category:Submillimetre astronomy Category:Astronomical observatories in Chile