double approximate_az_from_cross_el(double cross_el, double el)
{
if (el >= from_degrees(0.0) && el < from_degrees(85.0)) {
return cross_el / cos(el);
}
return cross_el;
}
void horizontal_to_equatorial(double az_deg, double el_deg, time_t lst_s, double lat_deg,
double* ra_hours, double* dec_deg)
{
double ha = 0.0;
double dec = 0.0;
double sa, ca, se, ce, sp, cp, x, y, z, r;
sincos(from_degrees(az_deg), &sa, &ca);
sincos(from_degrees(el_deg), &se, &ce);
sincos(from_degrees(lat_deg), &sp, &cp);
/* HA,Dec as x,y,z */
x = -ca * ce * sp + se * cp;
y = -sa * ce;
z = ca * ce * cp + se * sp;
/* To spherical */
r = sqrt(x * x + y * y);
ha = (r == 0.0) ? 0.0 : atan2(y, x);
dec = atan2(z, r);
*ra_hours = to_hours(from_seconds(lst_s) - ha);
*ra_hours = wrap_to(*ra_hours, 24.0);
*dec_deg = to_degrees(dec);
}
static bool decode(const Node& node, Calibration& calibration)
{
if(!node.IsMap())
{
ROS_ERROR("Error, calibration does not contain key value pairs, i.e. min_pulse, min_angle, max_pulse and max_angle");
return false;
}
else if(!node["min_pulse"])
{
ROS_ERROR("Error, calibration min_pulse not specified");
return false;
}
else if(!node["min_angle"])
{
ROS_ERROR("Error, calibration min_angle not specified");
return false;
}
else if(!node["max_pulse"])
{
ROS_ERROR("Error, calibration max_pulse not specified");
return false;
}
else if(!node["max_angle"])
{
ROS_ERROR("Error, calibration max_angle not specified");
return false;
}
calibration.min_pulse = node["min_pulse"].as<int>();
calibration.min_angle = from_degrees(node["min_angle"].as<double>());
calibration.max_pulse = node["max_pulse"].as<int>();
calibration.max_angle = from_degrees(node["max_angle"].as<double>());
return true;
}
void equatorial_to_horizontal(double ra_hours, double dec_deg, time_t lst_s, double lat_deg,
double* az_deg, double* el_deg)
{
double ha = from_seconds(lst_s) - from_hours(ra_hours);
double sh, ch, sd, cd, sp, cp, x, y, z, r, a;
sincos(ha, &sh, &ch);
sincos(from_degrees(dec_deg), &sd, &cd);
sincos(from_degrees(lat_deg), &sp, &cp);
/* Az,El as x,y,z */
x = -ch * cd * sp + sd * cp;
y = -sh * cd;
z = ch * cd * cp + sd * sp;
/* To spherical */
r = sqrt(x * x + y * y);
a = (fabs(r) < DBL_MIN) ? 0.0 : atan2(y, x);
*az_deg = to_degrees((a < 0.0) ? a + (2.0 * M_PI) : a);
*el_deg = to_degrees(atan2(z, r));
}
