OBJECT = DATA_SET DATA_SET_ID = "GO-J-UVS-3-RDR-SL9-G-FRAGMENT-V1.0" OBJECT = DATA_SET_INFORMATION DATA_SET_NAME = "GO UVS Tabular Data from the SL9-G Impact with Jupiter v1.0" DATA_SET_COLLECTION_MEMBER_FLG = "N" START_TIME = 1994-199T07:02:14.445Z STOP_TIME = 1994-199T07:13:21.712Z DATA_SET_RELEASE_DATE = 1996-07-01 DATA_OBJECT_TYPE = TABLE PRODUCER_FULL_NAME = "Karen E. Simmons" DETAILED_CATALOG_FLAG = "N" /**************************************************************************** /* SBN Note: added information about this data can be found in the DOCUMENT /* directory in the Galileo subdirectory which outlines the processing steps. /**************************************************************************** DATA_SET_DESC = " Data Set Overview ================= The UltraViolet Spectrometer (UVS) on the Galileo spacecraft took unique data of Comet Shoemaker-Levy/9's impact with Jupiter. A preliminary analysis of this data is presented in this submission to the Planetary Data System (PDS). It consists of four small tables with detached labels and documentation. Background ========== Galileo observed the SL9 fragment G impact by oscillating the scan-platform so that the fields of view of the scan-platform instruments moved to-and-fro across Jupiter. Each to-and-fro 'swath' lasted 10 2/3 sec, and consisted of two 5 1/3 sec 'passes'. A total of 124 passes were played back, 73 full or partial passes were useful from these and 52 of these were complete passes used in the analysis. The detection pass was a complete pass. During the observations, the UVS acquired one measurement every 7.6 msec (more precisely, 4.0/528 sec); during each measurement, the counting gate was open for 6.0 msec. Thus, each 10 2/3 sec swath contained 1408 6-msec samples. The data-taking was, however, not continuous, and the data received was occasionally corrupted. The data presented here and used in Hord et al. has all been inspected and verified. Each 10 2/3 sec swath consists of two 5 1/3 sec 'passes', labelled 'even' and 'odd'. Because the crescent Jupiter was much smaller than the UVS slit, the wavelength range of the light passing through the exit slit changed slightly as the crescent passed across the instrument field of view. Thus, the 'profiles' obtained during each pass do not have flat tops; the 'slope' of the profile tops reflect the wavelength dependence of the reflected solar spectrum in the neighborhood of 292 nm. When preparing the 'average' pass profile to compare with the 'impact flash' profile, the profiles from even- numbered passes were reversed to allow for this effect. The UVS data-taking began at S/C clock time 2486477, corresponding to Spacecraft Event Time (SCET) 94199/07:02:14.445 UTC. The One-Way Light Travel (OWLT) time from Jupiter to Earth was 00h:42m:51s and the OWLT from Jupiter to the Galileo spacecraft was 00h:13m:20s. The OWLT found in the data files, of 00h:29m:30.73s, converts from spacecraft time to Jupiter event time as seen at the Earth. Jupiter's angular diameter as seen by GLL was less than the UVS slit width. The half-maximum points recorded by UVS as Jupiter entered and left the slit therefore correspond to the instants when Jupiter's center of light entered and left the slit. Because the UV flash of the G fragment impact lay to the left of Jupiter's center of light, and was of approximately constant brightness for a period longer than its traverse time, the traverse of the flash across the slit was slightly displaced in time when compared with the traverse of Jupiter. Tables in the Dataset ===================== The data provided here for the G event are of four types: swaths, passes, impact, and flash. G_SWATHS DATA record 0 contains the elapsed time in seconds since the beginning of each to-and-fro swath (a swath consists of an 'even' pass, occupying words 0-703 of a 'swath', and an 'odd' pass occupying words 704-1407) record 1 contains the number of times a 'good' measurement was obtained at a given time (out of a maximum of 62) record 2 contains the average of the counts obtained during the 'good' measurements record 3 contains a triangular smooth of record 2, with a FWHM of 13 words (approximately 0.10 sec) record 4 contains the mask that isolates the 1.25-sec interval used to characterize the average signal from Jupiter when its crescent was fully within the slit during 'even' passes (ie #s 0, 2, 4, ...) record 5 contains the same as 4, except for 'odd' passes (1, 3, ..) record 6 contains a mask isolating the 0.75-sec (99-word) interval used to estimate the scattered-light background for 'even' passes record 7 contains the same as 6 for 'odd' passes (except a 1.0-sec, 132-word interval was used) G_PASSES DATA record 0 contains flags indicating whether a given pass was good (1) or bad (0) record 1 contains the adjustment to the timing of each pass needed to compensate for small errors in the scan-platform pointing record 2 contains the elapsed SCET at which the center-of-light of Jupiter was at the center of the slit during each pass record 3 contains the corresponding Earth Observation Time (EOT), expressed as seconds after 94-199/07:30:00.0 UT record 4 contains the average of the counts obtained during the 1.25-sec interval when Jupiter's crescent was fully within the UVS slit (see G_SWATHS.DAT, records 4 and 5) record 5 contains the average of the counts obtained during the background intervals (G_SWATHS.DAT, records 6 and 7) record 6 contains flags (used=1) indicating the passes used to obtain the 'average' profile used to compare with the 'impact flash' profile (ie, with pass #19) G_IMPACT DATA record 0 contains the counts recorded during the 'impact' pass (#19) record 1 contains a triangular smooth of record 0, with a FWHM of 13 words (0.10 sec) record 2 contains the average of 52 passes neighboring #19 (see G_PASSES.DAT, record 6) record 3 contains a triangular smooth of record 2, with a FWHM of 13 words (0.10 sec) G_FLASH DATA record 0 contains the elapsed times at the centers of 54 13-word (0.10-sec) bins, measured from the beginning of pass #19 record 1 contains the average counts recorded in each of these bins record 2 contains the corresponding averaged counts in the 52-pass average profile record 3 contains the excess of the pass #19 bins over the 52-pass average bins record 4 contains the 1-sigma uncertainties in these excesses record 5 contains a mask isolating the passage of the UV impact flash across the UVS slit record 6 contains the best straight-line fit to the count rates in the 'flash' bins Details of the structure and contents of these tables may be found in the detached label accompanying each table and in the UVSRDRS.ASC file. Processing ========== The raw UVS data received from the spacecraft were collected on EDRs by the UVS/EUV team at the Laboratory for Atmospheric and Space Physics at the University of Colorado at Boulder. The tables in the submitted dataset were generated during the analysis of UVS data from the Shoemaker-Levy 9 comet Fragment G impact with Jupiter. The detached PDS labels were prepared by the UVS/EUV team at LASP. (The raw data is provided in the binary file GFRAGTIM.DAT .) Data structure ============== The table files follow PDS structure and labelling conventions. A detached PDS label accompanies each file, and describes its structure and contents using ASCII keyword=value statements. Software ======== The four tables in this dataset are small and in ASCII character format. They are therefore printable and accessible with ordinary editing software. The Reduced Data Records were originally constructed by replacing the IDL 'plot' function with a 'write' function and converting the binary 'write' file to an ASCII 'print' file. Media/Format ============ This dataset is an electronic submission to PDS but may be included on a future CD-ROM volume of UVS data from the Jupiter Tour. Formats are based on standards for table objects established by PDS." CONFIDENCE_LEVEL_NOTE = "A one second error associated with a missing leapsecond in early versions of this data set has been corrected here." END_OBJECT = DATA_SET_INFORMATION OBJECT = DATA_SET_TARGET TARGET_NAME = JUPITER END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_TARGET TARGET_NAME = "SL9" END_OBJECT = DATA_SET_TARGET OBJECT = DATA_SET_HOST INSTRUMENT_HOST_ID = GO INSTRUMENT_ID = UVS END_OBJECT = DATA_SET_HOST OBJECT = DATA_SET_REFERENCE_INFORMATION REFERENCE_KEY_ID = "HORDETAL1995" END_OBJECT = DATA_SET_REFERENCE_INFORMATION END_OBJECT = DATA_SET END