1. Calibration of the COBE FIRAS instrument
- Author
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D. J. Fixsen, E. S. Cheng, D. A. Cottingham, R. E., Jr. Eplee, T. Hewagama, R. B. Isaacman, K. A. Jensen, J. C. Mather, D. L. Massa, S. S. Meyer, P. D. Noerdlinger, S. M. Read, L. P. Rosen, R. A. Shafer, A. R. Trenholme, R. Weiss, C. L. Bennett, N. W. Boggess, D. T. Wilkinson, and E. L. Wright
- Subjects
Physics ,business.industry ,media_common.quotation_subject ,Detector ,Cosmic microwave background ,Astrophysics::Instrumentation and Methods for Astrophysics ,Astronomy and Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Optics ,Space and Planetary Science ,Sky ,Calibration ,Black-body radiation ,business ,Noise (radio) ,Remote sensing ,Data reduction ,Background radiation ,media_common - Abstract
The Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite was designed to accurately measure the spectrum of the cosmic microwave background radiation (CMBR) in the frequency range 1-95/cm with an angular resolution of 7 deg. We describe the calibration of this instrument, including the method of obtaining calibration data, reduction of data, the instrument model, fitting the model to the calibration data, and application of the resulting model solution to sky observations. The instrument model fits well for calibration data that resemble sky condition. The method of propagating detector noise through the calibration process to yield a covariance matrix of the calibrated sky data is described. The final uncertainties are variable both in frequency and position, but for a typical calibrated sky 2.6 deg square pixel and 0.7/cm spectral element the random detector noise limit is of order of a few times 10(exp -7) ergs/sq cm/s/sr cm for 2-20/cm, and the difference between the sky and the best-fit cosmic blackbody can be measured with a gain uncertainty of less than 3%.
- Published
- 1994
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