static void compute_enu_directions(oskar_Mem* x, oskar_Mem* y, oskar_Mem* z,
int np, const oskar_Mem* l, const oskar_Mem* m, const oskar_Mem* n,
const oskar_Station* station, double GAST, int* status)
{
double ha0, dec0;
oskar_mem_ensure(x, np, status);
oskar_mem_ensure(y, np, status);
oskar_mem_ensure(z, np, status);
if (*status) return;
/* Obtain ra0, dec0 of phase centre */
const double lat = oskar_station_lat_rad(station);
const int pointing_coord_type = oskar_station_beam_coord_type(station);
if (pointing_coord_type == OSKAR_SPHERICAL_TYPE_EQUATORIAL)
{
const double ra0 = oskar_station_beam_lon_rad(station);
ha0 = (GAST + oskar_station_lon_rad(station)) - ra0;
dec0 = oskar_station_beam_lat_rad(station);
}
else if (pointing_coord_type == OSKAR_SPHERICAL_TYPE_AZEL)
{
/* TODO convert from az0, el0 to ha0, dec0 */
ha0 = 0.0;
dec0 = 0.0;
*status = OSKAR_ERR_FUNCTION_NOT_AVAILABLE;
return;
}
else
{
*status = OSKAR_ERR_SETTINGS_TELESCOPE;
return;
}
oskar_convert_relative_directions_to_enu_directions(
0, 0, 0, np, l, m, n, ha0, dec0, lat, 0, x, y, z, status);
}
static void compute_relative_directions(oskar_Mem* l, oskar_Mem* m,
oskar_Mem* n, int np, const oskar_Mem* x, const oskar_Mem* y,
const oskar_Mem* z, const oskar_Station* station, double GAST,
int* status)
{
double ha0, dec0, lat;
int pointing_coord_type;
if (*status) return;
/* Resize work arrays if needed */
if ((int)oskar_mem_length(l) < np) oskar_mem_realloc(l, np, status);
if ((int)oskar_mem_length(m) < np) oskar_mem_realloc(m, np, status);
if ((int)oskar_mem_length(n) < np) oskar_mem_realloc(n, np, status);
if (*status) return;
/* Obtain ra0, dec0 of phase centre */
lat = oskar_station_lat_rad(station);
pointing_coord_type = oskar_station_beam_coord_type(station);
if (pointing_coord_type == OSKAR_SPHERICAL_TYPE_EQUATORIAL)
{
double ra0;
ra0 = oskar_station_beam_lon_rad(station);
ha0 = (GAST + oskar_station_lon_rad(station)) - ra0;
dec0 = oskar_station_beam_lat_rad(station);
}
else if (pointing_coord_type == OSKAR_SPHERICAL_TYPE_AZEL)
{
/* TODO convert from az0, el0 to ha0, dec0 */
ha0 = 0.0;
dec0 = 0.0;
*status = OSKAR_FAIL;
return;
}
else
{
*status = OSKAR_ERR_SETTINGS_TELESCOPE;
return;
}
/* Convert from ENU to phase-centre-relative directions. */
oskar_convert_enu_directions_to_relative_directions(
l, m, n, np, x, y, z, ha0, dec0, lat, status);
}
void oskar_evaluate_beam_horizon_direction(double* x, double* y, double* z,
const oskar_Station* station, const double gast, int* status)
{
int beam_coord_type;
double beam_lon, beam_lat;
/* Check if safe to proceed. */
if (*status) return;
/* Get direction cosines in horizontal coordinates. */
beam_coord_type = oskar_station_beam_coord_type(station);
beam_lon = oskar_station_beam_lon_rad(station);
beam_lat = oskar_station_beam_lat_rad(station);
if (beam_coord_type == OSKAR_SPHERICAL_TYPE_EQUATORIAL)
{
double lon, lat, last;
lon = oskar_station_lon_rad(station);
lat = oskar_station_lat_rad(station);
last = gast + lon; /* Local Apparent Sidereal Time, in radians. */
oskar_convert_apparent_ra_dec_to_enu_directions_d(1, &beam_lon,
&beam_lat, last, lat, x, y, z);
}
else if (beam_coord_type == OSKAR_SPHERICAL_TYPE_AZEL)
{
/* Convert AZEL to direction cosines. */
double cos_lat;
cos_lat = cos(beam_lat);
*x = cos_lat * sin(beam_lon);
*y = cos_lat * cos(beam_lon);
*z = sin(beam_lat);
}
else
{
*status = OSKAR_ERR_INVALID_ARGUMENT;
}
/* Check if the beam direction needs to be one of a set of
* allowed (az,el) directions. */
if (oskar_station_num_permitted_beams(station) > 0)
{
int i, n, min_index = 0;
double az, el, cos_el, min_dist = DBL_MAX;
const double *p_az, *p_el;
/* Convert current direction cosines to azimuth, elevation. */
az = atan2(*x, *y);
el = atan2(*z, sqrt(*x * *x + *y * *y));
/* Get pointers to permitted beam data. */
n = oskar_station_num_permitted_beams(station);
p_az = oskar_mem_double_const(
oskar_station_permitted_beam_az_rad_const(station),
status);
p_el = oskar_mem_double_const(
oskar_station_permitted_beam_el_rad_const(station),
status);
/* Loop over permitted beams. */
for (i = 0; i < n; ++i)
{
double dist;
dist = oskar_angular_distance(p_az[i], az, p_el[i], el);
if (dist < min_dist)
{
min_dist = dist;
min_index = i;
}
}
/* Select beam azimuth and elevation based on minimum distance. */
az = p_az[min_index];
el = p_el[min_index];
/* Set new direction cosines. */
cos_el = cos(el);
*x = cos_el * sin(az);
*y = cos_el * cos(az);
*z = sin(el);
}
}
