DESIGNATE @int(1001:10099) CENTER @body REFERENCE STELLAR (0:1){ FRAME @name } (2:3){ DECLINATION @number | RIGHT ASCENSION @number | @options | RANGE @number } (0:3){ FROM @calendar | TO @calendar | EPOCH @calendar }
DESIGNATE @int(1001:10099) CENTER @body REFERENCE STELLAR (0:1){ FRAME @name } (2:3){ DECLINATION (1:2)@number | RIGHT ASCENSION (1:2)@number | @options | RANGE (1:2)@number } EPOCH @calendar (0:2){ FROM @calendar | TO @calendar }
When creating a designated object in this system, you must specify the right
ascension and declination of the object. The range to the object is optional,
and defaults to 10,000,000,000,000,000 kilometers (approximately 1000 light
years). You may specify the right ascension and declination relative to any
reference frame supported by the SPICE system. While not required, this
command has been designed under the assumption that you will choose an
inertial reference frame if you specify a reference frame.
If not supplied explicitly, the stellar reference frame is identical to the
IAU standard J2000 inertial reference frame.
If the proper motion of a stellar object is negligible, constant values for
right ascension and declination are normally supplied,
DEFINE RIGEL 1001; DESIGNATE RIGEL CENTER 0 REFERENCE STELLAR RIGHT ASCENSION 78.03319881 DEGREES DECLINATION - 8.25794522 DEGREES ;On the other hand,
DEFINE SIRIUS 1002; DESIGNATE SIRIUS CENTER 0 REFERENCE STELLAR RIGHT ASCENSION 100.7362138 DEGREES -0.00015794559 DEGREES/YEAR DECLINATION -16.6462019 DEGREES -0.00033649029 DEGREES/YEAR EPOCH 1 JAN 1900 ;Note that in these examples, the origin of the stellar frame is placed at the solar system barycenter (CENTER 0). By default, the range to the designated object is 1000 light years, so moving the origin to the Earth (CENTER 399) would generate a parallax of about 0.003 arc seconds.