Data Set Summary ================ Data Set ID: ULY-J-COSPIN-HET-3-RDR-FLUX-HIRES-V1.0 Instrument: COSPIN High Energy Telescope (HET) Instrument P.I.: R. Bruce McKibben (COSPIN), John A. Simpson (HET) Data Supplier: Data sampling rate: variable Data Set Start time: 1992-01-25T00:00:00.864Z Data Set Stop time: 1992-02-17T23:59:47.043Z 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: '(a24,10(1x,1pe10.3))' 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,10(1x,1pe10.3))' Data column descriptions ------------------------ time a24 spacecraft event time acc_time 1pe10.3 accumulation time for h1-h9 h1_rate 1pe10.3 h1 counting rate h2_rate 1pe10.3 h2 counting rate h3_rate 1pe10.3 h3 counting rate h4_rate 1pe10.3 h4 counting rate h5_rate 1pe10.3 h5 counting rate h6_rate 1pe10.3 h6 counting rate h7_rate 1pe10.3 h7 counting rate h8_rate 1pe10.3 h8 counting rate h9_rate 1pe10.3 h9 counting rate Missing data flag value ----------------------- Any data column whose value is -9.999e+10 is a missing data value. Data Description ================ [provided by the COSPIN HET investigators] Column 1: Date/time in format yyyy-mm-ddThh:mm:ss.sssZ Column 2: Accumulation time (second) for H1-H9 Column 3: H1 counting rate (c/s) Column 4: H2 counting rate (c/s) Column 5: H3 counting rate (c/s) Column 6: H4 counting rate (c/s) Column 7: H5 counting rate (c/s) Column 8: H6 counting rate (c/s) Column 9: H7 counting rate (c/s) Column 10: H8 counting rate (c/s) Column 11: H9 counting rate (c/s) A caveat is that during most of the Jupiter flyby, the counting rate logic was swamped by the extremely high intensity of electrons contained in the magnetosphere. As a result, we believe that the most reliable interpretation of the counting rates is that they become effectively measures of the integral intensity above the minimum energy required for an electron to penetrate to the most deeply buried detector required by the counting rate logic. For example, the H4 counting rate, which is nominally defined by the coincidence D1 D2 D4 K1 N[K4 A S (H)] becomes the integral intensity of all electrons with sufficient energy to reach K1, which, by the table below, based on the Berger and Seltzer tables and the thicknesses of the D1-D6 detectors, is ~2.7 MeV. The minimum electron energies required to trigger the counting rates, based simply on energy required to penetrate to the deepest detector and trigger its discriminator are as follows. For detectors beyond the midpoint of the telescope, we have assumed that there is sufficient material (instrument and spacecraft) behind the telescope that the easiest access to the detector is still through the front of the telescope. This may not be a good assumption. H1 ~0.5 MeV H2 ~2.6 MeV (higher level discriminators on D1 and D2 required) H3 ~1.5 MeV H4 ~2.7 MeV H5 ~8.9 MeV H6 ~1.2 MeV H7 ~2.7 MeV H8 ~1.5 MeV H9 ~16 MeV The detailed coincidence logic defining these counting rates is given in the [SIMPSONETAL1992A]. As indicated by the ~, these energies are very approximate. Our assumption is that essentially all the counting rates, even those such as H2 designed to discriminate against electrons, were dominated by electrons inside the magnetosphere. One additional word of explanation is required. In an ill-advised attempt to configure the HET to a mode to minimize the effects of the expected high counting rates on our slow logic, from approximately 1206 UT day 32 until approximately 0018 UT day 34, the HET S detector High Voltage was turned off, effectively turning off S, and the D1 detector was replaced by D3 in the counting rate logic. (Commands C1 and C9 as described in Table 8 of [SIMPSONETAL1992A].) The intent was to remove from the logic those detectors expected to be in near- saturation throughout the flyby, and thus to make the counting rates more interpretable. The change was effected before crossing the bowshock and magnetopause in order to establish a base-line in the new configuration prior to encountering the expected high fluxes in the magnetosphere. The actual effect turned out to be to increase the background in most of the counting rates to such a high level that features such as upstream particles escaping from the magnetosphere were completely obscured. After about a day and a half in this mode, it was decided to return to normal mode, and we remained in normal mode for the remainder of the flyby.