Astronomical Applications Department, U.S. Naval Observatory - NOVASC (Page 11)

VIRTUAL_STAR

short int virtual_star (double tjd, short int earth, fk5_entry *star,

double *ra, double *dec)

PURPOSE:
Computes the virtual place of a star at date 'tjd', given its
mean place, proper motion, parallax, and radial velocity for
J2000.0.

INPUT
ARGUMENTS:
tjd (double)
TDT Julian date for virtual place.
earth (short int)
Body identification number for the earth.
*star (struct fk5_entry)
Pointer to catalog entry structure (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.

RETURNED
VALUE:
(short int)
0...Everything OK.
>0...Error code from function 'solarsystem'.

Discussion:

See the discussion for function app_star. Function virtual_star is identical to app_star in input

arguments and use. Here, however, the output arguments provide the virtual place of the star. The virtual
place is essentially the apparent place expressed in the coordinate system of standard epoch J2000.0.