Bolocam

Bolocam
Name	Bolocam
Caption	Bolocam at the CSO prime focus (historical)
Operator	California Institute of Technology; Jet Propulsion Laboratory; University of Colorado Boulder
Location	Mauna Kea Observatory; Caltech Submillimeter Observatory
Wavelength	1.1 millimeter; 2.1 millimeter
Detectors	144 bolometers
Commissioning	2002
Decommissioned	2012
Predecessors	SHARC-II; MAMBO
Successors	AzTEC; SCUBA-2

Bolocam was a millimeter-wave bolometer camera deployed at high-altitude observatories to map continuum emission from astronomical sources. It operated on platforms including the Caltech Submillimeter Observatory at Mauna Kea and targeted molecular clouds, the Cosmic Microwave Background, and extragalactic surveys. Bolocam combined large instantaneous field of view with sensitive cryogenic bolometers to enable wide-area mapping that complemented instruments such as SCUBA, MAMBO, AzTEC, and SHARC-II.

Overview

Bolocam was developed by teams at the California Institute of Technology, Jet Propulsion Laboratory, and University of Colorado Boulder for observations at 1.1 mm and 2.1 mm. Construction drew on heritage from experiments like BOOMERanG, Maxima, BOOMERANG, and technologies advanced in projects such as Planck and South Pole Telescope. Deployed at facilities including the Caltech Submillimeter Observatory and later used in concert with observatories like BIMA Array and Combined Array for Research in Millimeter-wave Astronomy, Bolocam filled a niche between single-dish photometers and interferometers like ALMA and SMA.

Instrument Design and Technical Specifications

Bolocam comprised an array of 144 silicon nitride micromesh bolometers read out with cryogenic electronics developed at JPL and tested against standards from NIST. Optics used a cold reimaging system for coupling to the prime focus of telescopes such as the Caltech Submillimeter Observatory on Mauna Kea and the CSO site infrastructure. The focal plane provided an instantaneous field of view of several arcminutes with angular resolution set by telescopes like CSO and beam sizes comparable to instruments on IRAM 30m and JCMT. Cooling used dilution refrigerators and cryostats leveraging expertise from NASA suborbital programs and laboratory facilities at Caltech. Readout electronics interfaced with data acquisition systems modeled after designs used in BOOMERanG and ACBAR.

Observational Programs and Surveys

Bolocam conducted Galactic and extragalactic surveys, including high-latitude blank-field mapping and targeted studies of star-forming regions such as the Perseus molecular cloud, Orion Nebula, and Taurus Molecular Cloud. It contributed to wide-area surveys for cold cores and proto-stellar objects alongside projects like the Spitzer Space Telescope legacy surveys and follow-up with the Submillimeter Array. Bolocam participated in Sunyaev–Zel'dovich effect surveys of galaxy clusters, complementing catalogs from ROSAT, Chandra X-ray Observatory, and XMM-Newton and enhancing cluster samples used in cosmological analyses with datasets from WMAP and Planck.

Data Reduction and Calibration

Data pipelines for Bolocam employed time-domain filtering, principal component analysis, and map-making algorithms similar to those used by BOOMERanG, MAXIMA, and Planck teams. Calibration referenced planetary standards such as Mars, Jupiter, and Uranus with beam-matching tested against maps from SCUBA-2 and AzTEC. Atmospheric noise removal used skydip measurements and opacity monitoring routines developed at Mauna Kea Weather Center and compared with radiometric data from instruments like the CSO Tau Monitor. Pointing and astrometry were tied to catalogs such as the Two Micron All Sky Survey and the VLA calibrator lists, while flux standards referenced measurements from Herschel Space Observatory and archived values from IRAS.

Scientific Results

Bolocam produced catalogs of cold cores, dense clumps, and extragalactic sources that informed star formation studies linked to works on the Initial Mass Function and prestellar evolution investigated in regions like Perseus and Ophiuchus. Its Sunyaev–Zel'dovich observations contributed to cluster mass estimates used with scaling relations established by comparisons to Chandra X-ray masses and optical surveys such as the Sloan Digital Sky Survey. Bolocam maps aided multiwavelength studies combining data from Spitzer, Herschel, VLA, NOEMA, and ALMA to study protostellar envelopes, circumstellar disks, and dusty starburst galaxies identified in surveys like the Great Observatories Origins Deep Survey. Results influenced cosmological parameter constraints derived with WMAP and cross-checks with Planck cluster catalogs.

Development, Upgrades, and Successors

Bolocam's technology path informed successor instruments including AzTEC, SCUBA-2, and bolometer arrays employed on the Large Millimeter Telescope and South Pole Telescope. Upgrades to readout electronics and cryogenics paralleled developments in transition-edge sensor arrays and microwave kinetic inductance detectors explored for experiments like SPT-3G and Simons Observatory. The instrument's legacy persists in survey strategies used by facilities such as JCMT, IRAM, NOEMA, and ALMA and in methodologies transferred to space missions including Planck and concepts for future probes like CMB-S4.

Category:Astronomical instruments