KPL/SCLK FILENAME = "PSYC_255_SCLKSCET.00030.tsc" CREATION_DATE = "02-Apr-2024" Psyche Spacecraft Clock Kernel (SCLK) ================================================================= This file is a SPICE spacecraft clock (SCLK) kernel containing information required for time conversions involving the on-board Psyche spacecraft clock ('SCLK'). Version -------------------------------------------------------- Version History of Psyche Seed Kernel: Version 1.0 -- October 19, 2023 For Psyche the SCLK = 0 is at 2000-001T11:58:55.816 UTC, or 0 TDB seconds past J2000 TDB. The sub-seconds is set to a maximum of 65,536 ticks in the "SCLK01_MODULI_255" parameter. That was chosen for this SCLK kernel because all downlink packet secondary headers will include a 16-bit sub-seconds field with least significant bit resolution of 2^-16 second, so a tick is assumed to represent an interval of 2^-16 second. The end of the first partition is currently defined as the value in ticks of the maximum value 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. SCLK Format -------------------------------------------------------- The on-board clock, the conversion for which is provided by this SCLK file, consists of two fields: SSSSSSSSSS-FFFFF where: SSSSSSSSSS -- count of on-board seconds FFFFF -- count of fractions of a second with one fraction being 1/65536 of a second; normally this field value is within 0..65535 range. References -------------------------------------------------------- 1. "SCLK Required Reading" Inquiries -------------------------------------------------------- If you have any questions regarding this file contact NAIF at JPL Matt Barnes (818) 354-5942 Matthew.J.Barnes@jpl.nasa.gov Boris Semenov (818) 354-8136 Boris.Semenov@jpl.nasa.gov SCLK Kernel Data -------------------------------------------------------- The Psyche 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 = ( @2023-10-19T12:50:00 ) SCLK_DATA_TYPE_255 = ( 1 ) SCLK01_TIME_SYSTEM_255 = ( 2 ) \begintext In a particular partition of the Psyche spacecraft clock, the clock read-out consists of two separate stages: 1/18424652:24251 The first stage, an unsigned 32 bit field, represents the spacecraft clock seconds count. The second, an unsigned 16 bit field, represents counts of 2^-16 second increments of the spacecraft clock. The following keywords and their values establish this structure: \begindata SCLK_DATA_TYPE_255 = ( 1 ) SCLK01_TIME_SYSTEM_255 = ( 2 ) SCLK01_N_FIELDS_255 = ( 2 ) SCLK01_MODULI_255 = ( 4294967296 65536 ) SCLK01_OFFSETS_255 = ( 0 0 ) SCLK01_OUTPUT_DELIM_255 = ( 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_255 = ( 0.00000000000000e+00 ) SCLK_PARTITION_END_255 = ( 2.81474976710655e+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 scale (TDT) 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 SCLK = zero. The second time triplet below was entered manually and represents the SCLK and TDT times based on the nominal correlation at lift-off time. The rate of the second triplet was set to connect to the third triplet. The third time triplet below was entered manually and represents the SCLK and TDT times of the first time correlation packet in the first post-launch set generated by the spacecraft. The rate was set to nominal. \begindata SCLK01_COEFFICIENTS_255 = ( 0 @01-JAN-2000-12:00:00.000000 1.00000000000 49183384666112 @13-OCT-2023-14:21:32.000000 0.99998029367 49187036200960 @14-OCT-2023-05:50:08.902000 1.00000000000 49189419679744 @14-OCT-2023-15:56:17.895080 0.99999970249 49195532156928 @15-OCT-2023-17:50:46.867332 0.99999986991 49214365040640 @19-OCT-2023-01:40:13.829948 0.99999989882 49247084740608 @24-OCT-2023-20:21:16.779435 0.99999993327 49287667318784 @01-NOV-2023-00:21:57.738113 0.99999995982 49327540207616 @08-NOV-2023-01:22:09.713668 0.99999996495 49366620438528 @14-NOV-2023-23:00:46.692770 0.99999997082 49406052728832 @21-NOV-2023-22:08:55.675212 0.99999998181 49444404723712 @28-NOV-2023-16:42:20.664566 0.99999999007 49491621773312 @07-DEC-2023-00:50:15.657413 0.99999999555 49524729380864 @12-DEC-2023-21:09:57.655163 0.99999989139 49569425457152 @20-DEC-2023-18:36:45.581091 0.99999997899 49647815294976 @03-JAN-2024-14:52:19.555958 0.99999999098 49723535982592 @16-JAN-2024-23:49:05.545534 0.99999997593 49759861276672 @23-JAN-2024-09:47:05.532191 0.99999996395 49838991212544 @06-FEB-2024-09:10:52.488661 0.99999994803 49878664085504 @13-FEB-2024-09:20:12.457198 0.99999997603 49903325216768 @17-FEB-2024-17:51:51.448179 0.99999992948 49918317101056 @20-FEB-2024-09:24:29.432048 0.99999993255 49957969920000 @27-FEB-2024-09:28:43.391236 0.99999993564 49976756600832 @01-MAR-2024-17:06:25.372787 0.99999998494 49997622673408 @05-MAR-2024-09:32:56.367992 0.99999997334 50037176926208 @12-MAR-2024-09:12:06.351904 0.99999996339 50076731113472 @19-MAR-2024-08:51:15.329807 0.99999996445 50115950346240 @26-MAR-2024-07:05:13.308530 0.99999993343 50155052924928 @02-APR-2024-04:49:31.268810 0.99999993343 ) \begintext