Astronomical Applications Department, U.S. Naval Observatory novas c 2 doc Page 19
19
4.6
LOCAL_STAR
short int local_star (double tjd, body *earth, double deltat,
cat_entry *star, site_info *location,
double *ra, double *dec)
PURPOSE:
Computes the local place of a star, given its mean place, proper
motion, parallax, and radial velocity for J2000.0, and the
location of the observer.
INPUT
ARGUMENTS:
tjd (double)
TT (or TDT) Julian date for local place.
*earth (struct body)
Pointer to structure containing the body designation for the
Earth (defined in novas.h).
deltat (double)
Difference TT(or TDT)-UT1 at 'tjd', in seconds.
*star (struct cat_entry)
Pointer to catalog entry structure containing J2000.0 catalog
data with FK5-style units (defined in novas.h).
*location (struct site_info)
Pointer to structure containing observer's location (defined
in novas.h).
OUTPUT
ARGUMENTS:
*ra (double)
Local right ascension in hours, referred to mean equator and
equinox of J2000.
*dec (double)
Local 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 topo_star. Function local_star is identical to
topo_star in input arguments and use. The local place is essentially the topocentric place
expressed in the coordinate system of standard epoch J2000.0.
