Attitude Data Messages - CCSDS

CCSDS RECOMMENDED STANDARD FOR ATTITUDE DATA MESSAGES
ANNEX A
VALUES FOR SELECTED KEYWORDS
(NORMATIVE)
A1
OVERVIEW
The values in this annex represent the acceptable values for selected keywords. Each
keyword’s values delineated here are present in either an APM or AEM message. For details
and descriptions of the keyword interpretations, the reader is directed to reference [E4]. If
exchange partners wish to use different settings, they should be documented in an ICD.
A2
TIME_SYSTEM METADATA KEYWORD
TIME_SYSTEM Value
GMST
GPS
MET
MRT
SCLK
TAI
TCB
TDB
TT
UT1
UTC
Meaning/Description
Greenwich Mean Sidereal Time
Global Positioning System
Mission Elapsed Time
Mission Relative Time
Spacecraft Clock (receiver)
International Atomic Time
Barycentric Coordinated Time
Barycentric Dynamical Time
Terrestrial Time
Universal Time
Coordinated Universal Time
Note that if MET or MRT are chosen as the TIME_SYSTEM, then the epoch of either the
start of the mission for MET, or of the event for MRT, should either be given in a comment
in the message, or provided in an ICD. The time system for the start of the mission or the
event should also be provided in the comment or the ICD. If these values are used for the
TIME_SYSTEM, then the times given in the file denote a duration from the mission start or
CCSDS 504.0-B-1 Page A-1 May 2008