Data Set Summary ================ Data Set ID: ULY-J-GRB-2-RDR-RAW-COUNT-RATE-V1.0 Instrument: GRB Instrument P.I.: Kevin C. Hurley Data Supplier: Roger Williams Data sampling rate: variable Data Set Start time: 1992-01-25T00:00:00.126Z Data Set Stop time: 1992-02-17T23:59:59.941Z Naming convention ----------------- Data files in this data set are named according to the convention: Tyyddd.TAB where yy = the last two digits of the year ('92' for 1992) ddd = the day of the year covered by the file Record format ------------- These files can be read according to the FORTRAN format statement: '(a24,3(2x,i1),1x,1pe13.6,2x,i1)' where 'a24' is the time stamp in PDS format: yyyy-mm-ddThh:mm:ss.sssZ. The individual elements of the time field can be read according to the statement: '(i4,4(1x,i2),1x,f6.3,1x)' year, month, day, hour, minute, seconds. thus a record may be alternatively be read according to the format: '(i4,4(1x,i2),1x,f6.3,1x,3(2x,i1),1x,1pe13.6,2x,i1)' Data column descriptions -------- --------- ------------ time a24 spacecraft event time in format yyyy-mm-ddThh:mm:ss.sssZ header i1 header specification version i1 version subhead i1 subheader counts 1pe13.6 counts/second int_time i1 integration time Missing data flag value ----------------------- Any data column whose value is -9.999999e+10 is a missing data value. Data Description ================ GRB FILE FORMAT (REFERENCE: [HURLEYETAL1992] page 401-410) UDS REPRESENTATIVE: R. WILLIAMS (WILLIAMS@SUNSPOT.SSL.BERKELEY.EDU) ASCII FORMAT (*.TAB files): TIME = spacecraft event time in the format yyyy-mm-ddThh:mm:ss.sssZ HEADER = Header specification VERSION = Version SUBHEAD = Subheader COUNTS = Counts INT_TIME = Integration Time MODE FOR FILES: file mode file mode -------- -------- -------- -------- T92025 A1 T92037 A2 T92026 A1 T92038 A2 T92027 A1 T92039 A1 T92028 A1 T92040 A2 T92029 A1 T92041 A1 T92030 A1 T92042 A1 T92031 A2 T92043 A1 T92032 A2 T92044 A2 T92033 A2 T92045 A2 T92034 A2 T92046 A2 T92035 A2 T92047 A2 T92036 A2 T92048 A2 NOTES: BRIEF DESCRIPTION OF THE ULYSSES GRB DATA SET The archived data consist of count rates from the sum of two hemispherical detectors covering 4 pi steradians and operating continuously. The detectors are 3 mm thick CsI scintillators coupled to photomultiplier tubes. The nominal energy range is 25-150 keV, but the table below should be consulted to find the accurate thresholds for any day of the mission. A more complete description of the instrument may be found in [HURLEYETAL1992] and [COTINETAL1983]. Although the prime objectives of this investigation are the study of solar and cosmic x- and gamma-ray bursts, it should be noted that the experiment is also sensitive to solar protons and electrons. The former deposit energy directly in the scintillator if they are energetic enough, while the latter may produce x- radiation locally by bremsstrahlung. Thus although the counting rates are generally stable at about 500 c/s over the long term, there are periods of weeks to a month or so when the rates increase considerably due to particles. Examples may be found in March 1991 (solar protons) and February 1992 (particles in the Jovian magnetosphere). The time resolution of the data takes on one of four values depending on the telemetry rate and instrument operating mode: 0.25, 0.5, 1, or 2 seconds. Data rate changes produce short spikes in the count rates due to a processing artifact. These can in principle be corrected if the data are scanned and the rate changes are identified; the count rate spikes can then be adjusted to their correct values. There are also short (one sample long) count rate dropouts, due to an artifact of the onboard software. These may be seen in the sample plots (FIG1.GIF and FIG2.GIF); they cannot be corrected for. The following two figures give examples of solar and cosmic events in the data. [FIG1.GIF] gives the count rates for day 142, 1993, around 8.24 hours UT. The solar event is evident as a 300 second long increase. Note the count rate dropouts. [FIG2.GIF] includes a 20 second long cosmic gamma-ray burst from day 237, 1993 around 8.79 hours UT. References Cotin, F. et al., in The International Solar Polar Mission - Its Scientific Investigations, ESA SP-1050, p. 209, 1983 [COTINETAL1983] Hurley, K., et al. A&A Supp. Ser. 92(2), 401, 1992 [HURLEYETAL1992] YEAR DAY LOWER THRESHOLD UPPER THRESHOLD KEV/CHANNEL 1992 25 16.04 160.42 10.03 1992 26 15.98 159.83 9.99 1992 27 16.23 163.38 10.15 1992 28 15.99 159.95 10.00 1992 47 14.89 171.77 10.74 1992 48 14.87 171.57 10.72