FIRAS Explanatory Supplement

• FIRAS Overview
• About FIRAS
• About FIRAS Products
• FIRAS Documentation
• FIRAS Images
• FIRAS Browser
• Get FIRAS Data

Version 4 (dated 30 December 1997) is now on line. It contains detailed descriptions of the FIRAS instrument, its calibration and operation, and the Pass 4 FIRAS Data Sets.

You may download the Explanatory Supplement or use this Web page to browse it. An alternate PostScript version of the entire document (137 pages; Appendices excluded) is also provided. The document is also available by ftp in unprocessed form (LaTeX manuscript with Encapsulated PostScript figures and assorted ASCII and PostScript files). For advice on which files to download, please README.

To browse individual sections of the Explanatory Supplement, click on the section names below. Appendices A - F are manuscripts of journal or conference proceedings articles in PostScript form. Appendices G - J are flat ASCII files.

Main body of the Explanatory Supplement

• Abstract and Preface / PS
• Table of Contents / PS
• List of Figures / PS
• List of Tables / PS
• Introduction / PS
• Instrument Description / PS
• Mission Profile /
• Pre-Calibration Data Processing / PS
• Calibration of FIRAS Data / PS
• Destriping of FIRAS Data / PS
• Errors and Uncertainty Estimation / PS
• Modeling FIRAS Spectra / PS
• Reference Data Sets / PS
• Reading FIRAS Data / PS
• References / PS
• List of Appendices / PS

Appendix A

"The Cosmic Microwave Background Spectrum from the Full COBE FIRAS Data Set" - Fixsen, D.J. et al. 1996, ApJ, 473, 576 (figures not available in electronic form) / PS
Complete scanned version of the refereed article as provided by ADS

Appendix B

"Design for the COBE Far Infrared Absolute Spectrophotometer (FIRAS)" - Mather, J.C., Fixsen, D.J., and Shafer, R.A., 1993, COBE Preprint 93-10, in Proc. SPIE, 2019, 168 (SPIE: Bellingham, WA), from Conference on Infrared Spaceborne Remote Sensing, 11 - 16 July 1993, San Diego, CA / PS

Appendix C

"Calibration of the COBE FIRAS Instrument" / PS - Fixsen, D.J. et al. 1994, ApJ, 420, 457
Figure 1 - FIRAS optical layout (GIF)
Figure 2 / PS - A typical FIRAS interferogram
Figure 3 - Cutaway drawing of the external calibrator (GIF)
Figure 4 / PS - FIRAS antenna pattern
Figure 5 / PS - Transfer function for post-detector electronics
Figure 6 / PS - Etendue plots
Figure 7 / PS - Apodization function
Figure 8 / PS - Typical residual after subtraction of calibration model
Figure 9 / PS - Error terms for a typical point in the sky
Complete scanned version of the refereed article as provided by ADS

Appendix D

"Morphology of the Interstellar Cooling Lines Detected by COBE" / PS - Bennett, C.L. et al. 1994, ApJ, 434, 587
Figure 1 / PS - C⁺ 158 micron and N⁺ 205 micron line intensity maps
Figure 2a / PS - Intensities of 8 spectral lines vs. Galactic longitude
Figure 2b / PS - Galactic longitude profiles of various CO and C line intensities
Figure 3 / PS - C⁺ vs. N⁺ line intensity correlation
Figure 4 / PS - C⁺ and N⁺ line intensities vs. far-infrared continuum intensity
Figure 5 / PS - Maps of H I 21 cm line intensity and I(C⁺ 158um)/N(H I)
Figure 6 / PS - C⁺ 158 micron intensity vs. H I column density
Figure 7 / PS - C⁺ line/continuum intensity ratio vs. Galactic latitude
Complete scanned version of the refereed article as provided by ADS

Appendix E

"The COBE FIRAS Project Pipeline Software System" / PS - Read, S.M. et al. 1992, in First Annual Conference on Astronomical Data Analaysis and Systems, NOAO, Tucson, AZ (figures not available in electronic form)

Appendix F

"Pattern Matching in COBE Spectral Analysis" / PS - Isaacman, R.B., Read, S.M., and Barnes, W.J. 1992, in First Annual Conference on Astronomical Data Analaysis and Systems, NOAO, Tucson, AZ (figures not available in electronic form)

Appendix G

Concatenated listing of FIRAS FITS headers / TXT

Appendix H

FIRAS Record Definition Language files / TXT

Appendix I

FIRAS ASCII Format Reference Datasets / TXT

Appendix J

Listings of programs designed to read FIRAS data files / TXT

Appendix K (not yet available)

Intended to contain color versions of the Explanatory Supplement figures. Until this is ready, please refer to the FIRAS images page.