geoAstro.c File Reference

This file contains the wrapper routines to interface to the Novas (Naval Observatory Vector Astrometry Subroutine) Library. More...

#include <stdio.h>
#include <time.h>
#include "geoStars.h"
#include "novas.h"

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Macros
#define	MAJOR_PLANET   0
#define	BODY_EARTH   3
#define	BODY_SUN   10
#define	REDUCED_ACC   1

Functions
int	geoSunAzElNow (GEO_LOCATION *loc, double *az, double *el)
	this routine uses ANSI C time routines to obtain the current time and then get the az and el of the sun at this location More...
double	geoSunNowEl (double lat, double lon, double hgt)
	this routine uses the location and current time to get the elevation of the sun at this location More...
double	geoSunNowAz (double lat, double lon, double hgt)
	this routine uses the location and current time to get the azimuth of the sun at this location More...
int	geoSunAzEltm (GEO_LOCATION *loc, double *az, double *el, struct tm *newtime)
	this routine ingests an ANSI C time structure and then gets the az and el of the sun at this location based on this time. More...
int	geoGettm (int part)
int	geoSunAzElJD (GEO_LOCATION *loc, double *az, double *el, double tjd_now)
	This routine uses a previously determined Julian date and then gets the Az and El of the sun at this location based on the Julian date. More...
int	geoGetSunError (void)

Variables
int	geoSunError = 0
struct tm	tError

Detailed Description

This file contains the wrapper routines to interface to the Novas (Naval Observatory Vector Astrometry Subroutine) Library.

http://aa.usno.navy.mil/software/novas/novas_info.html

Definition in file geoAstro.c.

Macro Definition Documentation

#define BODY_EARTH   3

Definition at line 129 of file geoAstro.c.

#define BODY_SUN   10

Definition at line 130 of file geoAstro.c.

Referenced by geoSunAzElJD().

#define MAJOR_PLANET   0

Definition at line 128 of file geoAstro.c.

Referenced by geoSunAzElJD().

#define REDUCED_ACC   1

Definition at line 131 of file geoAstro.c.

Referenced by geoSunAzElJD().

Function Documentation

int geoGetSunError

(

void

)

Definition at line 198 of file geoAstro.c.

References geoSunError.

{
    return(geoSunError);
}

int geoGettm

(

int

part)

Definition at line 116 of file geoAstro.c.

References tError.

{
    switch(part)
    {
        case 1: return(tError.tm_year);
        case 2: return(tError.tm_mon);
        case 3: return(tError.tm_mday);
    }
    return(-999);
}

int geoSunAzElJD	(	GEO_LOCATION *	loc,
		double *	az,
		double *	el,
		double	tjd_now
	)

This routine uses a previously determined Julian date and then gets the Az and El of the sun at this location based on the Julian date.

Parameters

GEO_LOCATION	*loc : Location structure
double	*az : Azimuth in decimal degrees
double	*el : Elevation in decimal degrees

Return values

GEO_OK	on success
GEO_ERROR	on error

Definition at line 147 of file geoAstro.c.

References BODY_SUN, GEO_ERROR, GEO_OK, geoSunError, GEO_LOCATION::hgt, GEO_LOCATION::lat, GEO_LOCATION::lon, MAJOR_PLANET, and REDUCED_ACC.

Referenced by geoSunAzEltm().

{
    on_surface geo_loc;
    cat_entry  dummy_star;
    object     sun;
    double deltat = 60.0;     // 'deltat' is the difference in time scales, TT - UT1.
    double ra, dec, dis;
    double rar,decr;
    //   int error;

    /* Convert geo library info into Novas info */
    // geo_loc.latitude  =    loc->lat;
    // geo_loc.longitude =    loc->lon;
    // geo_loc.height    =    loc->hgt;
    // geo_loc.temperature =  30.0;     // degrees celcius
    // geo_loc.pressure  =    1000.0;   // pressure in millibars
    make_on_surface(loc->lat, loc->lon, loc->hgt, 30.0, 1000.0, &geo_loc);


    /* Set the planetary bodies to be worked with */
    /*geoSunError = set_body (MAJOR_PLANET,BODY_EARTH,"Earth", &earth);
   if(geoSunError)
   {
    //  printf ("Error %d from set_body.\n", geoSunError);
      return(GEO_ERROR);
   }
*/

    geoSunError = make_object (MAJOR_PLANET,BODY_SUN,"Sun",&dummy_star, &sun);
    if(geoSunError)
    {
        //printf ("Error %d from make_object.\n", geoSunError);
        return(GEO_ERROR);
    }

    /* Compute the Sun's position */
    //   geoSunError = topo_planet (tjd_now,&sun,&earth,deltat,&geo_loc, &ra,&dec,&dis);
    geoSunError = topo_planet (tjd_now,&sun,deltat,&geo_loc, REDUCED_ACC, &ra,&dec,&dis);
    if(geoSunError)
    {
        //  printf ("Error %d from topo_planet.\n", geoSunError);
        return(GEO_ERROR);
    }

    /* Convert to Azimuth and Elevation */
    equ2hor(tjd_now,deltat,REDUCED_ACC,0,0,&geo_loc,ra,dec,0,el,az,&rar,&decr);
    *el = 90.0 - *el; // correct elevation from zenith

    return(GEO_OK);
}

int geoSunAzElNow	(	GEO_LOCATION *	loc,
		double *	az,
		double *	el
	)

this routine uses ANSI C time routines to obtain the current time and then get the az and el of the sun at this location

Parameters

GEO_LOCATION	*loc : Location structure
double	*az : Azimuth in decimal degrees
double	*el : Elevation in decimal degrees

Return values

GEO_OK	on success
GEO_ERROR	on error

Definition at line 31 of file geoAstro.c.

References geoSunAzEltm().

Referenced by geoSunNowAz(), and geoSunNowEl().

{
    struct tm *newtime;
    long ltime=0L;

    /* Obtain coordinated universal time: */
    time( &ltime );
    newtime = gmtime( &ltime );

    return ( geoSunAzEltm(loc, az, el, newtime) );
}

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int geoSunAzEltm	(	GEO_LOCATION *	loc,
		double *	az,
		double *	el,
		struct tm *	newtime
	)

this routine ingests an ANSI C time structure and then gets the az and el of the sun at this location based on this time.

Parameters

GEO_LOCATION	*loc : Location structure
double	*az : Azimuth in decimal degrees
double	*el : Elevation in decimal degrees

Return values

GEO_OK	on success
GEO_ERROR	on error

Definition at line 98 of file geoAstro.c.

References geoSunAzElJD(), and tError.

Referenced by geoSunAzElNow().

{
    /* Obtain coordinated universal time: */
    double tjd_now;

    tError.tm_year=newtime->tm_year;
    tError.tm_mon=newtime->tm_mon;
    tError.tm_mday=newtime->tm_mday;

    tjd_now = julian_date((short)(newtime->tm_year+1900),
    (short)(newtime->tm_mon+1),
    (short)newtime->tm_mday,
    newtime->tm_hour + (newtime->tm_min/60.0)+(newtime->tm_sec/3600.0));

    return ( geoSunAzElJD(loc, az, el,tjd_now) );
}

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double geoSunNowAz	(	double	lat,
		double	lon,
		double	hgt
	)

this routine uses the location and current time to get the azimuth of the sun at this location

Parameters

double	lat : Latitude in degrees
double	lon : Longitude in degrees
double	hgt : Height in meters

Return values

double

: Azimuth in decimal degrees

Definition at line 75 of file geoAstro.c.

References GEO_DATUM_DEFAULT, geoInitLocation(), and geoSunAzElNow().

{
    GEO_LOCATION loc;
    double az,el;

    geoInitLocation(&loc, lat, lon, hgt, GEO_DATUM_DEFAULT,  "now");
    geoSunAzElNow(&loc, &az, &el);
    return(az);
}

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double geoSunNowEl	(	double	lat,
		double	lon,
		double	hgt
	)

this routine uses the location and current time to get the elevation of the sun at this location

Parameters

double	lat : Latitude in degrees
double	lon : Longitude in degrees
double	hgt : Height in meters

Return values

double

: Elevation in decimal degrees

Definition at line 54 of file geoAstro.c.

References GEO_DATUM_DEFAULT, geoInitLocation(), and geoSunAzElNow().

{
    GEO_LOCATION loc;
    double az,el;

    geoInitLocation(&loc, lat, lon, hgt, GEO_DATUM_DEFAULT,  "now");
    geoSunAzElNow(&loc, &az, &el);
    return(el);
}

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Variable Documentation

int geoSunError = 0

Definition at line 15 of file geoAstro.c.

Referenced by geoGetSunError(), and geoSunAzElJD().

struct tm tError

Definition at line 16 of file geoAstro.c.

Referenced by geoGettm(), and geoSunAzEltm().