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Compton Gamma-Ray Observatory Science Support Center

SMMGRS - SMM Gamma-Ray Burst Catalog

(Note: July 26, 1995 - The results presented here represent a preliminary processing of the SMM gamma-ray burst data. An update to this catalog is in progress. For more information contact Gerry Share at


SMM Gamma-Ray Spectrometer (GRS)

The Gamma-Ray Spectrometer was one of two instruments on the Solar Maximum Mission (SMM) which independently monitored cosmic gamma-ray bursts from SMM's launch in February 1980 until the end of the mission in 1989.

Instrument Information

The GRS was designed for investigation of the gamma-ray spectrum of solar flares (Forrest et al., 1980). The main detector was an array of seven gain-controlled 7.6 cm diameter X 7.6 cm thick NaI(Tl) detectors. A complete spectrum was obtained every 16.38 seconds in the energy range 0.3-9 MeV. The number of counts in three energy windows covering the 4.2-6.4 MeV range was read out every 2.048 seconds. In addition, the number of counts in an approximately 50 keV wide window near 300 keV was read out every 64 milliseconds. The spectrometer was shielded by a 2.5 cm thick CsI(Na) annulus and a 25 cm diameter X 7.6 cm thick CsI(Na) back detector. The shield elements defined a field of view of approximately 135 degrees (FWHM) in the solar direction. The CsI back detector and the seven NaI detectors together provided a high-energy spectrometer with approximately 100 cm**2 effective area and four energy channels from 10 to 100 MeV. The number of counts in those high-energy channels was read out every 2.048 seconds. The experiment was complemented by two 8 cm**2 X 0.6 cm thick NaI(Tl) detectors which measured the X-ray portion of the spectrum every 1.024 seconds in the range from 13 keV to 182 keV.


The SMM Gamma Ray Spectrometer (GRS) instrument is described in Norris, J.P., et al., 1986 February 1, Ap. J., 301:213-219.

Forrest et al., 1980, Bull. Am. Astr. Soc., 12, 890.

Questions about the SMMGRS database can be addressed to Jay Norris at GROSSC::NORRIS or

SMMGRS Gamma-Ray Burst Catalog

There are thirteen columns in the catalog -

  1. Name: Year, month, and day of burst in the format `GRB:YYMMDD`.
  2. DayNo: Day of year in the format yy.ddd.
  3. UT: Universal Time of burst onset in seconds of day.
  4. Duration: Duration of burst in seconds.
  5. VVMax: Ratio of observed to observable volume.
  6. Fluence: Total burst fluence (10**-6 erg/cm**2).
  7. Fluence_error: Error in burst fluence (10**-6 erg/cm**2).
  8. Earth_Angle: Angle: center of Earth to Sun as seen from SMM (decimal degrees).
  9. RA: Right ascension of SMM from center of Earth (decimal degrees).
  10. Dec: Declination of SMM from center of Earth (decimal degrees).
  11. ID: ID Method - Burst found by computer? (1 = yes, 0=no)
  12. SAA: Spacecraft near SAA? (1 = yes, 0=no)
  13. Confirmation: A list of confirming satellites (experiments which also observed the burst).

View the catalog

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This page was last modified on Monday, 01-Aug-2005 13:40:18 EDT.

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