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: http://www.izmiran.rssi.ru/projects/space/VEGA/coorsys
Дата изменения: Thu Jan 21 17:54:48 2010 Дата индексирования: Sat Apr 9 23:54:28 2016 Кодировка: Поисковые слова: propulsion |
Heliographic Inertial Coordinate System
(HGI):
The HGI coordinates are Sun centered and
inertially fixed with respect to an X-axis directed along the intersection
line of the ecliptic and solar equatorial planes. The solar equator plane
is inclined at 7.25 degrees from the ecliptic. This direction was towards
ecliptic longitude of 74.367 degrees on 1 January 1900 at 1200 UT ;because
of precession of the celestial equator, this longitude increases by 1.4
degrees/century. The Z axis is directed perpendicular and northward from
the solar equator, and the Y-axis completes the right-handed set. This
system differs from the usual heliographic coordinates (e.g. Carrington
longitudes) which are fixed in the frame of the rotating Sun.
Cometocentric (solar) Ecliptic Coordinate
System (CSE)
The FLYBY and BEFOREFLY files of the magnetic
field data contains data for intervals of the closest approach of the VEGA
spacecrafts to Haley comet.Files contains the following data: the position
of the spacecraft in cometocentric (solar) ecliptic coordinates (CSE),
magnetic field data in a coordinate system centered at the spacecraft with
axes parallel to the CSE-system.
CSE coordinate system for
the SC POSITION: axis origin at comet center, X-axis to the SUN,
Z-axis to ecliptic north pole, (X,Y)-plane is parallel to the ecliptic
plane.
CSE coordinate system for
the MAGNETIC FIELD DATA: spacecraft centered, axes parallel to the
CSE system for the position.
This coordinate system is
correct only for VERY SHORT TIME, about 4 hours around
the closest approach of the SC to the
Comet, since for a larger angular distance
of the SC from the Comet, the direction
to the Sun from both objects will be
different.