Astronomical Applications Department, U.S. Naval Observatory novas c 2 doc Page 20
20
4.7
VIRTUAL_PLANET
short int virtual_planet (double tjd, body *ss_object, body *earth,
double *ra, double *dec, double *dis)
PURPOSE:
Computes the virtual place of a planet or other solar system body.
INPUT
ARGUMENTS:
tjd (double)
TT (or TDT) Julian date for virtual place.
*ss_object (struct body)
Pointer to structure containing the body designation for the
solar system body (defined in novas.h).
*earth (struct body)
Pointer to structure containing the body designation for the
Earth (defined in novas.h).
OUTPUT
ARGUMENTS:
*ra (double)
Virtual right ascension in hours, referred to mean equator
and equinox of J2000.
*dec (double)
Virtual declination in degrees, referred to mean equator
and equinox of J2000.
*dis (double)
True distance from Earth to planet in AU.
RETURNED
VALUE:
(short int)
0...Everything OK.
>0...Error code from function `ephemeris'.
Discussion:
See the discussion for function app_planet. Function virtual_planet is identical to
app_planet in input arguments and use. Here, however, the output arguments provide the
virtual place of the planet. The virtual place is essentially the apparent place expressed in
the coordinate system of standard epoch J2000.0.
