Shadow History file format

File to store the times of satellite transitions in and out of the various shadow regimes.

see: ShadowEvent and ShadowHistory

Lines starting with the character "#" are ignored and considered a comment.

E.g. This is a comment.

Comments may also occur at any point within a line, starting from the first occurrence of the character "#" onwards.

Blank lines are ignored.

IMPORTANT NOTE: in this document, we refer to an epoch we call J2000GPS.

1. J2000GPS is distinct from the epoch J2000.0 (which the IAU 1994 Resolution C7 recommends be defined at the geocenter and at the date 2000 January 1.5 Terrestrial Time[TT], where TT = TDT).
2. J2000GPS is also distinct from the date 2000 January 1.5 UTC time, which we can refer to as J2000UTC. Exactly 13 leap seconds separate these epochs, i.e.: J2000GPS = J2000UTC - 13 = 2000-01-01 11:59:47.000 UTC
3. Times before and after J2000GPS are described in GPS seconds around this epoch, i.e. continuous time.

Each line corresponds to one shadow regime transition. It is required that regime transitions are listed in advancing time per satellite.

Fields are space delimited with the exception of the 8th field which is a calendar string wrapped in parentheses.

1) Satellite name
2) Name of body blocking the Sun for regime (3), typically Earth
3) Shadow regime being exited [Clear,Penumbra,Umbra]  
4) the word "to" for readability
5) Name of body blocking the Sun for regime (6), typically Earth
6) Shadow regime being entered [Clear,Penumbra,Umbra]
7) Seconds past J2000GPS. To get GPS seconds past GPS week 0
second 0, (6-JAN-1980 00:00:00.0000), add 630763200.
Seven digits of precision should be specified.
8) Character representation of time (7) for readability. This field
is wrapped in parentheses

Example:

GPS58 Earth Clear To Earth Penumbra 376061530.9570310 (2011-12-02 01:32:10.957031)
GPS58 Earth Penumbra To Earth Umbra 376061610.0585940 (2011-12-02 01:33:30.058594)
GPS58 Earth Umbra To Earth Penumbra 376064242.4080250 (2011-12-02 02:17:22.408025)
GPS58 Earth Penumbra To Earth Clear 376064321.7083620 (2011-12-02 02:18:41.708362)
GPS62 Earth Clear To Earth Penumbra 375978495.5200200 (2011-12-01 02:28:15.520020)
GPS62 Earth Penumbra To Earth Umbra 375978573.5229490 (2011-12-01 02:29:33.522949)