Astronomical Applications Department, U.S. Naval Observatory novas c 2 doc Page 16
16
4.3
APP_PLANET
short int app_planet (double tjd, body *ss_object, body *earth,
double *ra, double *dec, double *dis)
PURPOSE:
Compute the apparent place of a planet or other solar system body.
INPUT
ARGUMENTS:
tjd (double)
TT (or TDT) Julian date for apparent 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)
Apparent right ascension in hours, referred to true equator
and equinox of date 'tjd'.
*dec (double)
Apparent declination in degrees, referred to true equator
and equinox of date 'tjd'.
*dis (double)
True distance from Earth to planet at 'tjd' in AU.
RETURNED
VALUE:
(short int)
0...Everything OK.
>0...Error code from function 'ephemeris'.
Discussion:
This function computes the apparent place of a planet or other solar system body by
calling function ephemeris to obtain its rectangular coordinates, along with those of the
Earth. Other utility- and basic- level functions are also called. The user's choice of
ephemerides determines the values to be used in structures
ss_object
and
earth
,
which identify the solar system object and the Earth, respectively.
