Combined Array for Research in Millimeter-wave Astronomy

Combined Array for Research in Millimeter-wave Astronomy
Name	Combined Array for Research in Millimeter-wave Astronomy
Caption	CARMA observing site in the Inyo Mountains
Location	Eastern Sierra Nevada, California
Coordinates	37°N 118°W
Established	2005
Closed	2015
Telescopes	23 antennas (6 × 10.4 m, 9 × 6.1 m, 8 × 3.5 m)
Wavelength	millimeter (1 mm–3 mm)
Operator	California Institute of Technology; University of California; University of Illinois; University of Chicago; Smithsonian Astrophysical Observatory

Combined Array for Research in Millimeter-wave Astronomy The Combined Array for Research in Millimeter-wave Astronomy was a synthesis radio telescope array for millimeter-wave astronomy located in the Inyo Mountains near Bishop, California. It operated as a partnership among several academic and institutional partners and served as a pathfinder for interferometric techniques later used by facilities such as the Atacama Large Millimeter/submillimeter Array and the Karl G. Jansky Very Large Array. CARMA contributed to studies of star formation, protoplanetary disks, molecular clouds, and active galactic nuclei.

Overview

The array combined antennas and infrastructure from previous projects to create a 23-antenna interferometer integrating hardware and software developed by institutions including the California Institute of Technology, University of California, University of Illinois at Urbana-Champaign, University of Chicago, and Smithsonian Astrophysical Observatory. CARMA operated at millimeter wavelengths overlapping frequency bands used by the Nobeyama Radio Observatory, Institut de Radioastronomie Millimétrique, Max Planck Institute for Radio Astronomy, National Radio Astronomy Observatory, and European Southern Observatory. The facility supported researchers affiliated with institutions such as Harvard University, Massachusetts Institute of Technology, Princeton University, Stanford University, Yale University, Columbia University, and the University of Arizona.

History and Development

CARMA emerged from consolidation of legacy projects and antennas originally associated with the Owens Valley Radio Observatory, Berkeley-Illinois-Maryland Association array, and the Caltech Millimeter Array. Its development involved collaborations with organizations including NASA, National Science Foundation, Department of Energy laboratories, and national observatories like NRAO and IRAM. Key milestones paralleled developments at observatories such as Mauna Kea Observatories, Kitt Peak National Observatory, Arecibo Observatory, and the Submillimeter Array. CARMA’s timeline overlapped with major missions and programs including the Hubble Space Telescope, Chandra X-ray Observatory, Spitzer Space Telescope, Herschel Space Observatory, and the Sloan Digital Sky Survey, enabling multiwavelength follow-up studies involving research groups at Johns Hopkins University, University of California Santa Cruz, University of Colorado Boulder, and California Institute of Technology.

Technical Specifications

CARMA consisted of heterogeneous antennas (10.4 m, 6.1 m, 3.5 m) arranged to provide flexible baselines analogous to configurations used at the Very Large Array and Plateau de Bure Interferometer. Receiver systems covered the 1 mm to 3 mm bands, comparable to receivers at IRAM and Nobeyama, with correlator technology influenced by designs at NRAO and the Max Planck Institute. The correlator supported wideband and spectral-line modes used to detect transitions of molecules studied by research groups at the Jet Propulsion Laboratory, Space Telescope Science Institute, and Princeton Plasma Physics Laboratory. Site infrastructure drew on precedents from observatories such as Palomar Observatory, Lick Observatory, KAO, and Cerro Tololo Inter-American Observatory for logistics, power, and data transport, and interfaced with computing centers at University of Illinois, National Center for Supercomputing Applications, and NASA Ames Research Center for data reduction pipelines.

Science Goals and Key Results

CARMA targeted investigations of star formation, protoplanetary disks, molecular cloud structure, high-redshift galaxies, and active galactic nuclei, linking efforts with teams at the Smithsonian Astrophysical Observatory, Harvard-Smithsonian Center for Astrophysics, Max Planck Institute for Astronomy, and Leiden Observatory. Major scientific outputs included high-resolution imaging of protostellar envelopes, molecular line surveys complementing projects at ALMA and VLA, and continuum studies related to programs led by researchers at University of California Berkeley, University of Michigan, and University of Illinois. CARMA data contributed to multiwavelength campaigns involving the Keck Observatory, Subaru Telescope, Gemini Observatory, and the Very Large Telescope, and informed theoretical interpretation from groups at Princeton University, MIT, Caltech, and University of Cambridge. Results were cited by teams working on exoplanet formation at institutions such as Cornell University, University of Toronto, and University of Colorado, and by cosmology groups at Stanford University, University of Washington, and University of California San Diego.

Operations and Instrumentation

Day-to-day operations were coordinated among observatory staff and academic partners including Caltech, UC campuses, and the Smithsonian Astrophysical Observatory, with user support resembling services provided by NRAO and IRAM. Instrumentation included cryogenic receivers, heterodyne mixers provided by partners such as the Jet Propulsion Laboratory and National Radio Astronomy Observatory, and antenna control systems similar to those at ALMA and SMA. Observation scheduling and calibration used software and techniques comparable to CASA, AIPS, and MIRIAD, with data archiving and distribution involving computing centers at NCSA, NASA Goddard, and the University of California system. Training and outreach connected CARMA to programs at the National Science Foundation, American Astronomical Society, and regional universities including California State University and community colleges.

Collaborations and Funding

CARMA was funded by a combination of federal grants, institutional contributions, and partner investments, with agencies and organizations including the National Science Foundation, NASA, Department of Energy laboratories, and private foundations. Institutional partners included California Institute of Technology, University of California campuses, University of Illinois, University of Chicago, and Smithsonian Astrophysical Observatory, with scientific collaborations involving international institutions such as IRAM, Max Planck Society, European Southern Observatory, and universities across North America, Europe, and Asia. The collaborative model paralleled consortia behind projects like ALMA, VLA, and SMA, and fostered cooperative programs with the Keck Observatory, NOAO, and national laboratories including Lawrence Berkeley National Laboratory and Argonne National Laboratory.

Category:Radio telescopes Category:Millimeter astronomy Category:California Institute of Technology Category:National Science Foundation