KPL/SCLK DIF Spacecraft SCLK File for Primary (SCU A) On-board Clock, Science Version =========================================================================== This file is a SPICE spacecraft clock (SCLK) kernel containing information required for the primary (SCU A) Deep Impact Flyby (DIF) spacecraft on-board clock to UTC conversion. Production/History of this SCLK file -------------------------------------------------------- This file was created on 2005-07-14; the comments in the file were updated on 2005-09-14 in preparation for archiving in the Planetary Data System. This file was generated by the NAIF utility program MAKCLK, version 3.5.2, from the final DIF spacecraft SCLKvSCET file for SCU A, modified to improve correlation (see details in ``Particulars'' section of these comments.) At the time of release this file was named ``DIF_SCLKSCET.00015_tweaked.tsc''; it was later renamed to ``DIF_SCLKSCET.00015_science.tsc''. Particulars -------------------------------------------------------- Traditionally the SCLK correlation function provided in the SCLKvSCET file had to comply with two requirements (in order to maintain correct tagging/sorting by UTC in the ground system): 1) the correlation must be continuos, and 2) the must be backward compatible (meaning that drift rates for the past epochs must not change). To achieve that every update of SCLKvSCET introduced two points: one "real" data point with actual estimated drift and one "artificial" data point about 5000 seconds before the actual point with a bogus drift rate, just to connect the previous trend with the new one in a continuous fashion. Arguably, the right thing to do to make the SCLK kernel better reflect real clock trend was to have the ``artificial'' points dropped and change coefficients of the ``real'' points to ``connect'' the real points into a continuous piece-wise line function. This way the drift rates that were initially estimated slightly incorrectly would be changed to make the correlation match the reality better. Exactly this was done to the final official SCLKvSCET to get the modified version that used to produce this SCLK kernel. Usage -------------------------------------------------------- This file must be loaded into the user's program by a call to the FURNSH subroutine CALL FURNSH( 'this_file_name' ) in order to use the SPICELIB SCLK family of subroutines to convert DI spacecraft on-board clock to ET and vice versa. SCLK Format -------------------------------------------------------- The on-board clock, the conversion for which is provided by this SCLK file, consists of two fields: SSSSSSSSSS:FFF where: SSSSSSSSSS -- count of on-board seconds FFF -- count of fractions of a second with one fraction being 1/256 of a second References -------------------------------------------------------- 1. SCLK Required Reading Document 2. MAKCLK User's Guide Document 3. SFOC SCLKvSCET SIS Document Inquiries -------------------------------------------------------- If you have any questions regarding this file contact NAIF at JPL Charles H. Acton, Jr (818) 354-3869 Chuck.Acton@jpl.nasa.gov Boris V. Semenov (818) 354-8136 Boris.Semenov@jpl.nasa.gov SCLKvSCET File -------------------------------------------------------- This section contains the source SCLKvSCET file from which this SCLK kernel was made. MISSION-NAME=DEEP-IMPACT; SPACECRAFT-NAME=DIF; DATA-SET-ID=SCLK-SCET; FILE-NAME=DIF-SCLKSCET.00015_tweaked; PRODUCT-CREATION-TIME=2005-192T14:37:05; PRODUCT-VERSION-ID=00015; PRODUCER-ID=DSMS-TIME-SERVICES; APPLICABLE-START-TIME=2000-001T12:00:00.000; APPLICABLE-STOP-TIME=2006-004T18:06:12.961; MISSION-ENVIRONMENT=ops; MISSION-ID=27; SPACECRAFT-ID=140; *----SCLK0----- --------SCET0-------- -DUT-- --SCLKRATE-- 0.000 2000-001T12:00:00.000 64.184 1.000000000 158975000.000 2005-014T11:43:20.000 64.184 1.004153400 158976000.000 2005-014T12:00:04.153 64.184 1.000013295 159306000.000 2005-018T07:40:09.222 64.184 1.000016187 159881000.000 2005-024T23:23:37.991 64.184 1.000015454 162171000.000 2005-051T11:30:54.119 64.184 1.000015682 164167000.000 2005-074T13:58:00.509 64.184 1.000013460 164771000.000 2005-081T13:44:46.249 64.184 1.000010379 164910000.000 2005-083T04:21:27.501 64.184 1.000010067 165963000.000 2005-095T08:51:41.838 64.184 1.000013234 168899000.000 2005-129T08:25:31.708 64.184 1.000010259 169760000.000 2005-139T07:35:39.120 64.184 1.000008954 171944000.000 2005-164T14:15:58.706 64.184 1.000008123 173945000.000 2005-187T18:06:12.961 64.184 1.000007312 MAKCLK Setup file -------------------------------------------------------- This section contains the MAKCLK setup file used by the MAKCLK program to convert the source SCLKvSCET to this SCLK kernel. SCLKSCET_FILE = DIF_SCLKSCET.00015_tweaked OLD_SCLK_KERNEL = dif_template.tsc FILE_NAME = DIF_SCLKSCET.00015_tweaked.tsc NAIF_SPACECRAFT_ID = -140 LEAPSECONDS_FILE = naif0007.tls PARTITION_TOLERANCE = 3000 LOG_FILE = DIF_SCLKSCET.00015_tweaked.log Kernel DATA -------------------------------------------------------- \begindata SCLK_KERNEL_ID = ( @2005-07-14/14:17:47.00 ) SCLK_DATA_TYPE_140 = ( 1 ) SCLK01_TIME_SYSTEM_140 = ( 2 ) SCLK01_N_FIELDS_140 = ( 2 ) SCLK01_MODULI_140 = ( 4294967296 256 ) SCLK01_OFFSETS_140 = ( 0 0 ) SCLK01_OUTPUT_DELIM_140 = ( 1 ) SCLK_PARTITION_START_140 = ( 0.0000000000000E+00 ) SCLK_PARTITION_END_140 = ( 1.0995116277750E+12 ) SCLK01_COEFFICIENTS_140 = ( 0.0000000000000E+00 6.4184000000000E+01 1.0000000000000E+00 4.0697600000000E+10 1.5897506418400E+08 1.0041529999971E+00 4.0697856000000E+10 1.5897606833700E+08 1.0000153606061E+00 4.0782336000000E+10 1.5930607340600E+08 1.0000152504348E+00 4.0929536000000E+10 1.5988108217500E+08 1.0000157764192E+00 4.1515776000000E+10 1.6217111830300E+08 1.0000132214429E+00 4.2026752000000E+10 1.6416714469300E+08 1.0000095033113E+00 4.2181376000000E+10 1.6477115043300E+08 1.0000090071941E+00 4.2216960000000E+10 1.6491015168500E+08 1.0000136153846E+00 4.2486528000000E+10 1.6596316602200E+08 1.0000101737057E+00 4.3238144000000E+10 1.6889919589200E+08 1.0000086085947E+00 4.3458560000000E+10 1.6976020330400E+08 1.0000089679487E+00 4.4017664000000E+10 1.7194422289000E+08 1.0000071239380E+00 4.4529920000000E+10 1.7394523714500E+08 1.0000073120000E+00 ) \begintext