EVP Data Format
EVP Data Format
The EVP data has existed in two different formats. The early EVP data format was based on
an event message that was 172 bytes long. This "long" EVP format was modified just before the
time of the CGRO launch to reduce the data storage requirements. The so-called "short" EVP
format has been in use since March of 1991. The "short" EVP event message requires 68 bytes
of storage.
The Long EVP Data Format
This corresponds to DSD version numbers 0. The physical data structure for long EVP records is as follows:
- INTEGER*4 - TJD
- INTEGER*4 - COMPASS tics
- REAL*4 - D1 Energy Deposit (keV)
- REAL*4 - D2 Energy Deposit (keV)
- REAL*4 - Total Energy Deposit (keV)
- REAL*4 - Error on Total Energy Deposit (keV)
- REAL*4 - Phibar (radians)
- REAL*4 - Error on Phibar (radians)
- REAL*4 - X-location in D1 (in mm)
- REAL*4 - Y-location in D1 (in mm)
- REAL*4 - Lambda location in D1
- REAL*4 - X-location in D2 (in mm)
- REAL*4 - Y-location in D2 (in mm)
- REAL*4 - Lambda location in D2
- REAL*4 - PSD
- REAL*4 - ToF
- CHAR*8 - Event Classification
- INTEGER*4 - Module Combination
- REAL*4 - Photon scatter direction, galactic longitude (radians)
- REAL*4 - Photon scatter direction, galactic latitude (radians)
- REAL*4 - Photon scatter direction, celestial right ascension (radians)
- REAL*4 - Photon scatter direction, celestial declination (radians)
- REAL*4 - Photon scatter direction, spacecraft azimuth (radians)
- REAL*4 - Photon scatter direction, spacecraft zenith (radians)
- REAL*4 - Photon scatter direction, Earth-centered latitude (radians)
- REAL*4 - Photon scatter direction, Earth-centered longitude (radians)
- REAL*4 - Earth horizon angle (radians)
- (3)REAL*4 - Direction cosines of scatter vector in spacecraft coordinates
- (3)REAL*4 - Direction cosines of scatter vector in galactic coordinates
- (3)REAL*4 - Direction cosines of scatter vector in celestial coordinates
- (3)REAL*4 - Direction cosines of scatter vector in earth-centered coordinates
- (3)REAL*4 - Direction cosines of scatter vector in horizon coordinates
The Short EVP Data Format
This corresponds to DSD version numbers 1, 2 or 3. The physical data structure for short EVP records is as follows:
- INTEGER*2 - X-location in D1 (in mm, scaled by a factor of 32)
- INTEGER*2 - Y-location in D1 (in mm, scaled by a factor of 32)
- INTEGER*2 - Lambda location in D1 (scaled by a factor of 256)
- INTEGER*2 - X-location in D2 (in mm, scaled by a factor of 32)
- INTEGER*2 - Y-location in D2 (in mm, scaled by a factor of 32)
- INTEGER*2 - Lambda location in D2 (scaled by a factor of 256)
- INTEGER*2 - PSD (scaled by a factor of 128)
- INTEGER*2 - ToF (scaled by a factor of 128)
- INTEGER*2 - Module Combination
- INTEGER*2 - Rejection Flag
- INTEGER*2 - Veto Flag
- INTEGER*2 - TJD
- INTEGER*4 - COMPASS tics
- REAL*4 - D1 Energy Deposit (keV)
- REAL*4 - D2 Energy Deposit (keV)
- REAL*4 - Phibar (radians)
- REAL*4 - Photon scatter direction, galactic longitude (radians)
- REAL*4 - Photon scatter direction, galactic latitude (radians)
- REAL*4 - Photon scatter direction, spacecraft azimuth (radians)
- REAL*4 - Photon scatter direction, spacecraft zenith (radians)
- REAL*4 - Earth horizon angle (radians)
- CHAR*8 - Event Classification
Last Update: February 17, 1998
Dr. Mark McConnell
Space Science Center
Morse Hall, Rm 312
University of New Hampshire
Durham, NH 03824
Phone: (603) 862-2047
Fax: (603) 862-4685
Mark.McConnell@unh.edu