KPL/SCLK \begintext FILENAME = "rbspa_sclk_0042.tsc" CREATION_DATE = "14-Oct-2012" RBSP-A Spacecraft Clock Kernel (SCLK) =========================================================================== This file is a SPICE spacecraft clock (SCLK) kernel containing information required for time conversions involving the on-board RBSP-A spacecraft clock. Version -------------------------------------------------------- RBSP-A SCLK Kernel Version: Version 0.5 -- January 26, 2010 -- Stan Cooper Initial (seed) time coefficients triplet set for MET = 0 at 2010-001-00:00:00 UTC for RBSP. Note that this was set using the current value of 34 leap seconds. Note also that this is the MET = 0 UTC epoch expected to be used for Observatory I&T as well as for RBSP launch, although that plan could change. Version 0.4 -- November 15, 2005 -- Stan Cooper Corrected the statement "SPICE uses linear interpolation" to "SPICE uses linear extrapolation". This was confirmed earlier with Scott Turner as noted in the MESSENGER SCLK kernels. Version 0.3 -- May 11, 2005 -- Stan Cooper Modified file header to avoid loss of header text when kernel is automatically updated. Also, added FILENAME and CREATION_DATE fields that are automatically updated. Version 0.2 -- June 25, 2003 -- Scott Turner The number of digits representing fractional seconds present in the TDT component of the SCLK coefficient triples were inadequate for NEW HORIZONS' requirements. The field now contains 6 digits instead of 3. Version 0.1 -- June 24, 2003 -- Scott Turner This kernel was created as an initial input to the NEW HORIZONS SCLK update process. It provides values for the fields required to handle the SCLK string format, as well as the baseline units of the clock correlation coefficients that the update process is to introduce or correct. The initial clock rate established in this file assumes no drift from the parallel time system (TDT). Further the clock coefficients indicate the clock starts on the following epoch: 1/0:0 (SCLK) 01-JAN-2003-00:01:04.184 (TDT) The end of the first partition is currently defined as the value in ticks of the rollover of the spacecraft clock. Usage -------------------------------------------------------- This file is used by the SPICE system as follows: programs that make use of this SCLK kernel must 'load' the kernel, normally during program initialization. Loading the kernel associates the data items with their names in a data structure called the 'kernel pool'. The SPICELIB routine FURNSH loads text kernel files, such as this one, into the pool as shown below: FORTRAN: CALL FURNSH ( SCLK_kernel_name ) C: furnsh_c ( SCLK_kernel_name ); Once loaded, the SCLK time conversion routines will be able to access the necessary data located in this kernel for their designed purposes. References -------------------------------------------------------- 1. "SCLK Required Reading" Inquiries -------------------------------------------------------- If you have any questions regarding this file or its usage, contact: Scott Turner (443)778-1693 Scott.Turner@jhuapl.edu Kernel Data -------------------------------------------------------- The first block of keyword equals value assignments define the type, parallel time system, and format of the spacecraft clock. These fields are invariant from SCLK kernel update to SCLK kernel update. The RBSP spacecraft clock is represented by the SPICE type 1 SCLK kernel. It uses TDT, Terrestrial Dynamical Time, as its parallel time system. \begindata SCLK_KERNEL_ID = ( @2012-10-14T06:01:02 ) SCLK_DATA_TYPE_362 = ( 1 ) SCLK01_TIME_SYSTEM_362 = ( 2 ) \begintext In a particular partition of the RBSP spacecraft clock, the clock read-out consists of two separate stages: 1/18424652:24251 The first stage, a 32 bit field, represents the spacecraft clock seconds count. The second, a 16 bit field, represents counts of 20 microsecond increments of the spacecraft clock. The following keywords and their values establish this structure: \begindata SCLK01_N_FIELDS_362 = ( 2 ) SCLK01_MODULI_362 = ( 4294967296 50000 ) SCLK01_OFFSETS_362 = ( 0 0 ) SCLK01_OUTPUT_DELIM_362 = ( 2 ) \begintext This concludes the invariant portion of the SCLK kernel data. The remaining sections of the kernel may require updates as the clock correlation coefficients evolve in time. The first section below establishes the clock partitions. The data in this section consists of two parallel arrays, which denote the start and end values in ticks of each partition of the spacecraft clock. SPICE utilizes these two arrays to map from spacecraft clock ticks, determined with the usual modulo arithmetic, to encoded SCLK--the internal, monotonically increasing sequence used to tag various data sources with spacecraft clock. \begindata SCLK_PARTITION_START_362 = ( 0.00000000000000e+00 ) SCLK_PARTITION_END_362 = ( 2.14748364799999e+14 ) \begintext The remaining section of the SCLK kernel defines the clock correlation coefficients. Each line contains a 'coefficient triple': Encoded SCLK at which Rate is introduced. Corresponding TDT Epoch at which Rate is introduced. Rate in TDT (seconds) / most significant clock count (~seconds). SPICE uses linear extrapolation to convert between the parallel time system and encoded SCLK. The triples are stored in the array defined below. The first time triplet below was entered manually and represents the approximate time (in TDT) at which MET = zero. The current plan for RBSP is that the given epoch will be used for both Observatory I&T and launch. Note that the conversion from UTC to TDT used 34 leap seconds. \begindata SCLK01_COEFFICIENTS_362 = ( 0 @01-JAN-2010-00:01:06.184000 1.00000000000 4202112050000 @30-AUG-2012-17:05:07.891232 0.99999984920 4206967000000 @31-AUG-2012-20:03:26.876589 0.99999984713 4211827150000 @01-SEP-2012-23:03:29.861730 0.99999984111 4216147150000 @02-SEP-2012-23:03:29.848002 0.99999985547 4219566900000 @03-SEP-2012-18:03:24.838117 0.99999984727 4223526800000 @04-SEP-2012-16:03:22.826021 0.99999984775 4228409900000 @05-SEP-2012-19:11:04.811152 0.99999988046 4233247100000 @06-SEP-2012-22:03:28.799587 0.99999981170 4237747150000 @07-SEP-2012-23:03:29.782640 0.99999983623 4242067150000 @08-SEP-2012-23:03:29.768490 0.99999991454 4246104050000 @09-SEP-2012-21:29:07.761590 0.99999980300 4250707150000 @10-SEP-2012-23:03:29.743454 0.99999983303 4255027150000 @11-SEP-2012-23:03:29.729028 0.99999992134 4259014100000 @12-SEP-2012-21:12:28.722756 0.99999980074 4263487100000 @13-SEP-2012-22:03:28.704930 0.99999983038 4267994950000 @14-SEP-2012-23:06:05.689638 0.99999987270 4271586950000 @15-SEP-2012-19:03:25.680493 0.99999985103 4276267050000 @16-SEP-2012-21:03:27.666549 0.99999982788 4280947150000 @17-SEP-2012-23:03:29.650438 0.99999992264 4284907050000 @18-SEP-2012-21:03:27.644311 0.99999980785 4289407100000 @19-SEP-2012-22:03:28.627017 0.99999982551 4293907150000 @20-SEP-2012-23:03:29.611313 0.99999988385 4297326900000 @21-SEP-2012-18:03:24.603369 0.99999982809 4302007000000 @22-SEP-2012-20:03:26.587278 0.99999985305 4306687100000 @23-SEP-2012-22:03:28.573523 0.99999990004 4310836250000 @24-SEP-2012-21:06:31.565228 0.99999978838 4315147050000 @25-SEP-2012-21:03:27.546983 0.99999986957 4323426950000 @27-SEP-2012-19:03:25.525384 0.99999981842 4328107100000 @28-SEP-2012-21:03:28.508388 0.99999988478 4332902950000 @29-SEP-2012-23:42:05.497336 0.99999990459 4336587050000 @30-SEP-2012-20:10:07.490306 0.99999977222 4340887000000 @01-OCT-2012-20:03:26.470717 0.99999988711 4345026950000 @02-OCT-2012-19:03:25.461370 0.99999985031 4349166900000 @03-OCT-2012-18:03:24.448976 0.99999982047 4353847000000 @04-OCT-2012-20:03:26.432172 0.99999986408 4366987050000 @07-OCT-2012-21:03:27.396452 0.99999985314 4370766900000 @08-OCT-2012-18:03:24.385350 0.99999987490 4375447000000 @09-OCT-2012-20:03:26.373640 0.99999982641 4379046800000 @10-OCT-2012-16:03:22.361142 0.99999986827 4383546850000 @11-OCT-2012-17:03:23.349286 0.99999983770 4388046900000 @12-OCT-2012-18:03:24.334679 0.99999985386 4392907050000 @13-OCT-2012-21:03:27.320473 0.99999985329 ) \begintext