SharpAstrology.SwissEph 0.5.1

SharpAstrology.SwissEph - Ephemerides for SharpAstrology

About

This package provides an implementation of the IEphemerides interface from SharpAstrology.Base. It attempts to mimic the behavior of the C library swisseph (version 2.10.3).

SharpAstrology Packages

Install

dotnet add package SharpAstrology.SwissEph

Simple usage

using System.Text.Json;
using SharpAstrology.Enums;
using SharpAstrology.Ephemerides;
using SharpAstrology.Interfaces;

// Use Moshier, so you don't need the swiss eph files or JPL files
var ephemeridesService = new SwissEphemeridesService(ephType: EphType.Moshier);

// Calculate positional information for Sun, Moon and Venus on January 1st 2024
//
// Use UTC time or it will throw
var pointInTime = new DateTime(2024, 1, 1, 0, 0, 0, DateTimeKind.Utc);

using (IEphemerides eph = ephemeridesService.CreateContext())
{
    var sunPosition = eph.PlanetsPosition(Planets.Sun, pointInTime);
    Console.WriteLine(JsonSerializer.Serialize(sunPosition));
    // {
    // "Longitude":280.0390123591898,
    // "Latitude":0.00016036961321834312,
    // "Distance":0.9833183562567887,
    // "SpeedLongitude":1.0189783966864485,
    // "SpeedLatitude":-3.780307931918674E-05,
    // "SpeedDistance":-1.1317598853344111E-05
    // }

    var moonPosition = eph.PlanetsPosition(Planets.Moon, pointInTime);
    Console.WriteLine(JsonSerializer.Serialize(moonPosition));
    // {
    // "Longitude":155.9922487287969,
    // "Latitude":3.567636008224304,
    // "Distance":0.0027048134096186458,
    // "SpeedLongitude":11.848401014998416,
    // "SpeedLatitude":-0.7336498562140658,
    // "SpeedDistance":4.901106714722023E-06
    // }

    var venusPosition = eph.PlanetsPosition(Planets.Venus, pointInTime);
    Console.WriteLine(JsonSerializer.Serialize(venusPosition));
    // {
    // "Longitude":242.6123495376748,
    // "Latitude":1.9498137075115765,
    // "Distance":1.1819079026603012,
    // "SpeedLongitude":1.2159947235695916,
    // "SpeedLatitude":-0.029584567802327894,
    // "SpeedDistance":0.006288212288100938
    // }

    // Calculate house cusp longitudes in the porphyrius system for location London 
    var houseCusps = eph.HouseCuspPositions(pointInTime, 51.509865, -0.118092, HouseSystems.Porphyrius);
    Console.WriteLine(houseCusps.Cross[Cross.Asc]);
    // 187,07504557640635

    Console.WriteLine(houseCusps.Cross[Cross.Mc]);
    // 99,22014310543506

    Console.WriteLine(houseCusps.HouseCusps[Houses.House1]);
    // 187,07504557640635
}

// Calculate sidereal position for Mars with Lahiri ayanamsa
using (IEphemerides eph = ephemeridesService.CreateContext(Ayanamsas.Lahiri))
{
    var marsPosition = eph.PlanetsPosition(Planets.Mars, pointInTime, EphCalculationMode.Sidereal);
    Console.WriteLine(JsonSerializer.Serialize(marsPosition));
    // {
    // "Longitude":243.11750614191982,
    // "Latitude":-0.5505163268692346,
    // "Distance":2.423806754147523,
    // "SpeedLongitude"::0.7413840351773113,
    // "SpeedLatitude":-0.009739411236392903,
    // "SpeedDistance":-0.00303531177482181
    // }
}

EphCalculationMode.Sidereal applies to every supported object, the lunar nodes and the astrological Earth included. For all of them the sidereal longitude is the tropical longitude minus the ayanamsa. The latitude and the distance stay untouched, and the longitude speed differs by the proper motion of the ayanamsa alone.

Use swiss eph files or JPL files for more precision

Follow the instruction from the original swisseph project and download the files you want. Than save to files into a folder and use the path to that folder in the SwissEphemeridesService constructor.

using SharpAstrology.Ephemerides;
using SharpAstrology.Interfaces;

SwissEphemeridesService ephemeridesService;

// for swiss eph files
ephemeridesService = new SwissEphemeridesService(rootPathToEph: "[PATH_TO_SWISSEPH_ROOT_FOLDER]", EphType.Swiss);
using (IEphemerides eph = ephemeridesService.CreateContext())
{
    // calculate positions here
}

// for JPL files
ephemeridesService = new SwissEphemeridesService(rootPathToEph: "[PATH_TO_JPL_ROOT_FOLDER]", EphType.Jpl);
using (IEphemerides eph = ephemeridesService.CreateContext())
{
    // calculate positions here
}

A JPL folder should hold the swiss eph files as well. A JPL kernel contains the main bodies only, so asteroids like Chiron are always read from the seas files, which is what the original C library does too.

Fail instead of silently losing precision

By default a missing .se1 file makes the calculation fall back to Moshier for that body, matching the C library. Applications that must not compute with a weaker source behind the user's back can switch that off. A missing file then throws a FileNotFoundException naming the expected path, and a missing folder throws a DirectoryNotFoundException. House cusps and angles need no files at all and keep working either way.

ephemeridesService = new SwissEphemeridesService(
    rootPathToEph: "[PATH_TO_SWISSEPH_ROOT_FOLDER]",
    ephType: EphType.Swiss,
    allowMoshierFallback: false);

Note that the mean lunar node is implemented by the Moshier mean element series only. Without the Moshier fallback, only the true node is available.