// get a vector in ESU coordinates to a celestial body from a EUS position (like a camera or object) // - body = (e.g "Sun", "Venus", "Moon", etc) // - date = date of observation (Date object) export function getCelestialDirection(body, date, pos) { let LLA; // if a position is provided, use that to calculate the LLA of the observer // realistically this won't make any significant difference for the Sun, // the biggest difference will be for the Moon, then nearby planets if (pos !== undefined) { LLA = EUSToLLA(pos); } else { // default to the local origin, should be fine for the sun. LLA = V3(Sit.lat, Sit.lon, 0) } let observer = new Astronomy.Observer(LLA.x, LLA.y, LLA.z); const celestialInfo = Astronomy.Equator(body, date, observer, false, true); const ra = (celestialInfo.ra) / 24 * 2 * Math.PI; // Right Ascension NOTE, in hours, so 0..24 -> 0..2π const dec = radians(celestialInfo.dec); // Declination return getCelestialDirectionFromRaDec(ra, dec, date); }