A Java port of Ephemeris calculations by Peter Hayes. Since the original JavaScript version of the code could not be found, we are unable to link to it. There are a few versions available on github and a few hosted versions too. This version is more or less an exact port of the original (specifically the calculations which are based on Jean Meeus' calculations). This version is being provided only as a library and so does not include a front-end.
The code provides calculators for determining the positions of the Sun, Moon, Planets and several stars as viewed from a particular position on Earth.
mvn clean package
Sample code below shows how you can use each of the calculators to generate the Ephemeris.
The location on Earth from where you want to view the astronomical body
// Create an instance of the observatory
double latitude = 13.0068;
double longitude = 76.0996;
ZonedDateTime time = ZonedDateTime.of(2017, 11, 7, 0, 0, 0, 0, ZoneId.of("UTC")); //Date and time in UTC
Place place = new Place("Hassan", latitude, Pole.NORTH, longitude, Pole.EAST, TimeZone.getTimeZone("Asia/Calcutta"), "", "");
Observatory hassan = new Observatory(place, time); //observatory is a place at a specific time
Calculating position of the sun as viewed from the Observatory
// Create an instance of the Sun position calculator
SunPositionCalculator solarCalc = new SunPositionCalculator();
SunPosition sunPosition = solarCalc.getPosition(hassan);
sunPosition.getRiseTime(); //Rise time
sunPosition.getSetTime(); //Set time
sunPosition.getAzimuth(); //Azimuth
sunPosition.getAltitude(); //Elevation
There's a convenience method to generate the Ephemeris for a period.
int timeIntervalInMinutes = 10; //Positions to be calculated every 10 minutes from the start time
ZonedDateTime anotherTime = ZonedDateTime.of(2017, 11, 8, 0, 0, 0, 0, ZoneId.of("UTC")); //Date and time in UTC
List<SunPosition> ephemerides = sun.getEphemeris(obs, time, anotherTime, timeIntervalInMinutes);
Calculating position of the moon as viewed from the Observatory
MoonPositionCalculator lunarCalc = new MoonPositionCalculator();
MoonPosition moonPosition = lunarCalc.getPosition(hassan);
You can generate the Ephemeris with a specified interval as with the SunCalculator.
Calculating position of a planet as viewed from the Observatory
PlanetPositionCalculator planetCalc = new PlanetPositionCalculator();
Planet mars = PlanetCatalog.byName("Mars");
PlanetPosition marsPosition = planetCalc.getPosition(mars, hassan);
The Ephemeris can be generated as with the SunCalculator.
Calculating the position of a Star as viewed from the Observatory
StarCalculator starCalculator = new StarCalculator();
Star casA = StarCatalog.byIdAndConstellation("a", "cas");
StarPosition casAPosition = starCalc.getPosition(casA, hassan);
The Ephemeris can be generated as with the SunCalculator.
This project is licensed under the terms of the Apache 2 license.