KPL/SCLK \begintext FILENAME = "rbspb_sclk_0045.tsc" CREATION_DATE = "15-Oct-2012" RBSP-B Spacecraft Clock Kernel (SCLK) =========================================================================== This file is a SPICE spacecraft clock (SCLK) kernel containing information required for time conversions involving the on-board RBSP-B spacecraft clock. Version -------------------------------------------------------- RBSP-B SCLK Kernel Version: Version 0.6 -- June 9, 2010 -- Dave Carl Initial version of the RBSP-B seed kernel copied exactly from Version 0.5 of the RBSP-A seed kernel with all "362" replaced by "363" and "A/a" replaced by "B/b" . . . Version History of RBSP-A Seed Kernel: 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 = ( @2012-10-15T06:02:14 ) SCLK_DATA_TYPE_363 = ( 1 ) SCLK01_TIME_SYSTEM_363 = ( 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_363 = ( 2 ) SCLK01_MODULI_363 = ( 4294967296 50000 ) SCLK01_OFFSETS_363 = ( 0 0 ) SCLK01_OUTPUT_DELIM_363 = ( 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_363 = ( 0.00000000000000e+00 ) SCLK_PARTITION_END_363 = ( 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_363 = ( 0 @01-JAN-2010-00:01:06.184000 1.00000000000 4207327150000 @31-AUG-2012-22:03:29.388229 0.99999946389 4211827200000 @01-SEP-2012-23:03:30.339979 0.99999957994 4215607050000 @02-SEP-2012-20:03:27.308224 0.99999954307 4219927050000 @03-SEP-2012-20:03:27.268745 0.99999954368 4224787200000 @04-SEP-2012-23:03:30.224389 0.99999953934 4229109150000 @05-SEP-2012-23:04:09.184570 0.99999958037 4233427200000 @06-SEP-2012-23:03:30.148330 0.99999947656 4237747200000 @07-SEP-2012-23:03:30.103105 0.99999965779 4241397100000 @08-SEP-2012-19:20:08.078124 0.99999951871 4246387200000 @09-SEP-2012-23:03:30.030090 0.99999949220 4250347100000 @10-SEP-2012-21:03:27.989873 0.99999962113 4254389150000 @11-SEP-2012-19:30:48.959245 0.99999952422 4259347200000 @12-SEP-2012-23:03:29.912066 0.99999947600 4263667200000 @13-SEP-2012-23:03:29.866792 0.99999963594 4267447050000 @14-SEP-2012-20:03:26.839270 0.99999953080 4272354100000 @15-SEP-2012-23:19:07.793222 0.99999948111 4276587050000 @16-SEP-2012-22:50:06.749293 0.99999957786 4280046950000 @17-SEP-2012-18:03:24.720082 0.99999954496 4284907100000 @18-SEP-2012-21:03:27.675851 0.99999951773 4289587200000 @19-SEP-2012-23:03:29.630710 0.99999933045 4293187000000 @20-SEP-2012-19:03:25.582505 0.99999954421 4296246650000 @21-SEP-2012-12:03:18.554614 0.99999966771 4302547200000 @22-SEP-2012-23:03:29.512742 0.99999957906 4306147000000 @23-SEP-2012-19:03:25.482436 0.99999954564 4311007150000 @24-SEP-2012-22:03:28.438271 0.99999952425 4315327150000 @25-SEP-2012-22:03:28.397166 0.99999960450 4319467100000 @26-SEP-2012-21:03:27.364419 0.99999951153 4323967150000 @27-SEP-2012-22:03:28.320456 0.99999954650 4327927050000 @28-SEP-2012-20:03:26.284540 0.99999958248 4332435100000 @29-SEP-2012-21:06:07.246896 0.99999950903 4337107200000 @30-SEP-2012-23:03:29.201019 0.99999954775 4340887100000 @01-OCT-2012-20:03:27.166830 0.99999957639 4345453300000 @02-OCT-2012-21:25:31.128144 0.99999947376 4349887200000 @03-OCT-2012-22:03:29.081478 0.99999955223 4354524200000 @04-OCT-2012-23:49:09.039952 0.99999958869 4358167100000 @05-OCT-2012-20:03:27.009985 0.99999950576 4363027250000 @06-OCT-2012-23:03:29.961943 0.99999962794 4366627050000 @07-OCT-2012-19:03:25.935156 0.99999952684 4371127100000 @08-OCT-2012-20:03:26.892571 0.99999954507 4374906950000 @09-OCT-2012-17:03:23.858180 0.99999954760 4379226950000 @10-OCT-2012-17:03:23.819093 0.99999954715 4384627250000 @11-OCT-2012-23:03:29.770182 0.99999954962 4388047000000 @12-OCT-2012-18:03:24.739378 0.99999954708 4392727100000 @13-OCT-2012-20:03:26.696984 0.99999954628 4397227150000 @14-OCT-2012-21:03:27.656149 0.99999954721 ) \begintext