The Spacecraft Time Correlation file (*SC*TCS.FIT) contains the On-Board Data Handler (OBDH) time and the corresponding UTC. The epoch for UTC time reference is: 1958, January 1. More details about the definition of the time packets is given by [12] and [13]. One file is created for each observation and for each slew period. Each file consists of a single binary table whose columns are listed in Table 25.
The UTC is calculated as follows:
Alongside the Spacecraft Time Correlation file, a Spacecraft Reconstructed Time Correlation file (*SC*TCX.FIT) is available as well and has been used by the SAS since version v6.0 (March 2004). The Reconstructed Time Correlation data is Time Correlation Data corrected for known anomalies in the correction of Earth Reception Time (ERT) for signal propagation delay and corrected for symmetric discontinuities in Corrected ERT introduced by differences in Ground Station Clocks. The binary table columns are given in Table 25. The first 12 columns are the same as in the *SC*TCS.FIT file, and six additional columns are present. Details of the orbit files are provided in [11].
Name | Type | Units | Description |
FRAME | 1J | COUNTER | |
OBTCOARS | 1J | SECOND | Coarse COBT |
OBTFINE | 1J | Fine COBT | |
UTCDAY | 1I | UTC day corresponding to COBT | |
UTCMILLI | 1J | UTC ms of day corresponding to COBT | |
UTCMICRO | 1I | UTC s of day corresponding to COBT | |
CORRPARA | A39 | Slope of least squares fit | |
CORRPARB | A39 | Abscissa of least square fit | |
UTCFLAG | 1I | UTC quality flag | |
ERTIME | 27A | Corrected Earth received time | |
GSID | 5A | Ground station identifier | |
ERTIMERAW | 27A | RAW Earth received time | |
Additional columns only in reconstructed file | |||
UTCREAL | D | UTC | |
OBTREAL | D | COBT | |
PASS | I | Pass Number | |
GS | I | Ground Station Identifier | |
PREDUTC | D | ||
RESIDUAL | D |