The far infrared absolute spectrophotometer (FIRAS): Cosmic background spectrum, dipole and distortions

Conference · Wed Jan 01 00:00:00 EST 1992 · American Astronomical Society, Bulletin; (United States)

OSTI ID:6667768

Fixsen, D J; Cheng, E S; Cottingham, D A; Eplee, R E; Massa, D L; Mather, J C; Meyer, S M; Shafer, R A; Wright, E L ^[1]

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1. Univ. of California, Los Angeles (United States)

The FIRAS (Far Infrared Absolute Spectrophotometer) instrument on the COBE is designed to measure differences between the cosmic microwave background spectrum and the theoretically predicted blackbody spectrum. This paper reports details of the calibration and analysis methods used to achieve accuracy and precisions of better than 0.05% of the peak brightness from 2 to 20 cm[sup -1]. The calibration is done by least squares fitting of an instrument model to observations of the calibration blackbodies and horn antennas at a wide variety of temperatures. The model includes the bolometer detectors, the emissivities of the IR sources, and error parameters for vibrations, thermometer noise and calibration, and multipass radiation. The analysis of the sky include fits to a uniform (CBR), dipole, and an average galactic spectrum. The fits, residuals, and error estimates leading to these spectra will be shown, and the spectra will be compared with predictions and the y and [mu] distortion. Limits for [mu] and y will be reported along with the best values and their errors for the CBR temperature, the dipole amplitude, the dipole color temperature, and an estimate for the galactic radiation at the galactic poles. FIRAS may also be applied to research in other scientific disciplines.

• OSTI ID: 6667768
• Report Number(s): CONF-930189-; CODEN: AASBAR
• Journal Information: American Astronomical Society, Bulletin; (United States), Vol. 24:4; Conference: 181. meeting of the American Astronomical Society (AAS), Phoenix, AZ (United States), 3-7 Jan 1993; ISSN 0002-7537
• Country of Publication: United States
• Language: English

Related Subjects

47 OTHER INSTRUMENTATION
74 ATOMIC AND MOLECULAR PHYSICS
FAR INFRARED RADIATION
SPECTROPHOTOMETRY
MEASURING INSTRUMENTS
CALIBRATION
BLACKBODY RADIATION
COSMIC RADIATION
LEAST SQUARE FIT
MICROWAVE RADIATION
THEORETICAL DATA
DATA
ELECTROMAGNETIC RADIATION
INFORMATION
INFRARED RADIATION
IONIZING RADIATIONS
MAXIMUM-LIKELIHOOD FIT
NUMERICAL DATA
NUMERICAL SOLUTION
RADIATIONS
440800* - Miscellaneous Instrumentation- (1990-)
664200 - Spectra of Atoms & Molecules & their Interactions with Photons- (1992-)