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https://github.com/djben/spacetime
Astronomical space coordinate and time conversion. Calculate Julian day, local sidereal time and ecliptic obliquity with great precision.
https://github.com/djben/spacetime
astronomy carthage conversion coordinate equatorial julian-date sidereal sidereal-time swift swift-3
Last synced: 2 months ago
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Astronomical space coordinate and time conversion. Calculate Julian day, local sidereal time and ecliptic obliquity with great precision.
- Host: GitHub
- URL: https://github.com/djben/spacetime
- Owner: DJBen
- License: gpl-3.0
- Created: 2017-07-23T09:56:11.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2018-01-03T09:08:43.000Z (almost 7 years ago)
- Last Synced: 2024-10-14T22:21:34.320Z (2 months ago)
- Topics: astronomy, carthage, conversion, coordinate, equatorial, julian-date, sidereal, sidereal-time, swift, swift-3
- Language: Swift
- Homepage:
- Size: 1.6 MB
- Stars: 16
- Watchers: 2
- Forks: 4
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# SpaceTime
[](https://swift.org)
[](https://www.gnu.org/licenses/gpl-3.0)
[](https://github.com/Carthage/Carthage)
[](https://travis-ci.org/DJBen/SpaceTime)
## Overview
- Conversion among [equatorial coordinate](https://en.wikipedia.org/wiki/Equatorial_coordinate_system) (right ascension and declination), [horizontal coordinate](https://en.wikipedia.org/wiki/Horizontal_coordinate_system) (azimuth and altitude),
[ecliptic coordinate](https://en.wikipedia.org/wiki/Ecliptic_coordinate_system) (longitude and latitude) and their corresponding Cartesian equivalents.
- Calculate [Julian Day](https://en.wikipedia.org/wiki/Julian_day) and [Local sidereal time](https://en.wikipedia.org/wiki/Sidereal_time).
- High precision calculation of the [obliquity of ecliptic](https://en.wikipedia.org/wiki/Ecliptic) good to 0″.04 / 1000 years over 10000 years.
- Matrix / Quaternion transformation from celestial coordinate system to local tangent plane. Supports [North-East-Down](https://en.wikipedia.org/wiki/North_east_down) coordinate from [earth-centered, earth-fixed](https://en.wikipedia.org/wiki/ECEF) coordinate system for any given longitude, latitude and timestamp.
## Demo
You can find a demo project under `SpaceTimeDemo` directory.
It showcases several useful scenarios.
## Installation
### Carthage
github "DJBen/SpaceTime" ~> 0.4.0
## Usage
Equatorial to horizontal coordinate:
```swift
// Supply observer location and timestamp
let locTime = ObserverLocationTime(location: location, timestamp: JulianDay.now)
let vegaCoord = EquatorialCoordinate(rightAscension: radians(hours: 18, minutes: 36, seconds: 56.33635), declination: radians(degrees: 38, minutes: 47, seconds: 1.2802), distance: 1)
// Azimuth and altitude of Vega
let vegaAziAlt = HorizontalCoordinate.init(equatorialCoordinate: vegaCoord, observerInfo: locTime)
```
Ecliptic coordinate of Pollux at standard equinox of J2000.0.
```swift
let ra = DegreeAngle(116.328942)
let dec = DegreeAngle(28.026183)
let eclipticCoord = EclipticCoordinate(longitude: ra, latitude: dec, distance: 1, julianDay: .J2000)
eclipticCoord.longitude.wrappedValue // 113.21563
eclipticCoord.latitude.wrappedValue // 6.68417
```
Greenwich Mean Sidereal Time:
```swift
SiderealTime.init(julianDay: JulianDay.now)
```
Local Apparent Sidereal Time:
```swift
// Get location from GPS or hard code
let locTime = ObserverLocationTime(location: location, timestamp: JulianDay.now)
let localSidTime = SiderealTime.init(observerLocationTime: locTime)
```
More use cases can be found in the source and test cases.