Time Constants¶
Constants related to time systems, epochs, and time conversions.
Julian Date References¶
MJD_ZERO¶
module-attribute
¶
MJD_ZERO: float = 2400000.5
Convert a string or number to a floating-point number, if possible.
Value: 2400000.5 days
Offset of Modified Julian Date (MJD) with respect to Julian Date (JD). For any time t:
MJD2000¶
module-attribute
¶
MJD2000: float = 51544.5
Convert a string or number to a floating-point number, if possible.
Value: 51544.5 days
Modified Julian Date of January 1, 2000 12:00:00 (J2000.0 epoch). Value is independent of time system.
GPS_ZERO¶
module-attribute
¶
GPS_ZERO: float = 44244.0
Convert a string or number to a floating-point number, if possible.
Value: 44244.0 days
Modified Julian Date of the start of GPS time (January 6, 1980 00:00:00 UTC).
Time System Offsets¶
All offset values are in seconds.
GPS ↔ TAI¶
GPS_TAI¶
module-attribute
¶
GPS_TAI: float = -19.0
Convert a string or number to a floating-point number, if possible.
Value: -19.0 seconds
Offset of GPS time with respect to TAI: GPS = TAI + GPS_TAI
TAI_GPS¶
module-attribute
¶
TAI_GPS: float = 19.0
Convert a string or number to a floating-point number, if possible.
Value: 19.0 seconds
Offset of TAI time with respect to GPS: TAI = GPS + TAI_GPS
TT ↔ TAI¶
TT_TAI¶
module-attribute
¶
TT_TAI: float = 32.184
Convert a string or number to a floating-point number, if possible.
Value: 32.184 seconds
Offset of Terrestrial Time with respect to TAI: TT = TAI + TT_TAI
TAI_TT¶
module-attribute
¶
TAI_TT: float = -32.184
Convert a string or number to a floating-point number, if possible.
Value: -32.184 seconds
Offset of TAI with respect to Terrestrial Time: TAI = TT + TAI_TT
GPS ↔ TT¶
GPS_TT¶
module-attribute
¶
GPS_TT: float = -51.184
Convert a string or number to a floating-point number, if possible.
Value: 13.184 seconds
Offset of GPS time with respect to TT: GPS = TT + GPS_TT
Computed as: GPS_TAI + TAI_TT
TT_GPS¶
module-attribute
¶
TT_GPS: float = 51.184
Convert a string or number to a floating-point number, if possible.
Value: -13.184 seconds
Offset of TT with respect to GPS time: TT = GPS + TT_GPS