# node-ephem

> Calculator/parser for JPL ephemeris data

Latest version **1.4.0** (published 2015-05-16) · GPLv3 license · 0 weekly downloads

## Install

```sh
npm install node-ephem
pnpm add node-ephem
yarn add node-ephem
bun add node-ephem
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.4.0 |
| Published | 2015-05-16 |
| First published | 2015-04-22 |
| Weekly downloads | 0 |
| License | GPLv3 |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 2 |
| Known vulnerabilities | 0 |
| Install scripts | yes |
| GitHub stars | 5 |
| Author | Nenad Vukicevic |
| Maintainers | vukicevic |

## Links

- npm: https://www.npmjs.com/package/node-ephem
- Repository: https://github.com/vukicevic/node-ephem
- Issues: https://github.com/vukicevic/node-ephem/issues
- npm.io page: https://npm.io/package/node-ephem

## Dependencies (2)

- [nan](https://npm.io/package/nan.md) ^1.8.0
- [bindings](https://npm.io/package/bindings.md) ^1.2.1

## Recent versions

- 1.4.0 (latest) — 2015-05-16
- 1.3.0 — 2015-05-12
- 1.2.0 — 2015-04-26
- 1.1.0 — 2015-04-25
- 1.0.0 — 2015-04-22

## README

node-ephem
==========

Parse JPL DE planetary ephemerides and calculate the position of planets (and moon) at a given time.

This module is based on [Project Pluto](http://www.projectpluto.com/jpl_eph.htm)'s code for calculating planetary positions from JPL ephemerides.

Required
--------

This module uses publicly available planetery ephemeride files which can be downloaded from NASA's Jet Propulsion Laboratory [FTP server](http://tinyurl.com/qabeu3g). More information on which file to chose can be found [here](http://tinyurl.com/olea84t).

Usage
-----

Require the module.

```javascript
var ephem = require('node-ephem');
```

Load ephemerides which you downloaded, by providing a path to it:

```javascript
var e430 = ephem.load('./eph/linux_p1550p2650.430');
```

Find Mars, relative to the Sun, at this instant:

```javascript
var position = e430.find(ephem.bodies.MARS, ephem.bodies.SUN, ephem.julian(new Date));
```

Find RA/Dec of Neptune at this moment, adjusted for light-time:

```javascript
var radec = ephem.equatorial(e430.observe(ephem.bodies.MERCURY, ephem.bodies.EARTH, ephem.julian(new Date)));
```

Functions
---------

node-ephem exports:

Function | Parameters | Description
---|---|---
load | path | Load planetary ephemerides file, returns ephemeris object
julian | date | convert Date to Julian day (J2000 epoch, TT)
equatorial | position | Cartesian to Equаtorial

ephemeris object:

Function | Parameters | Description
---|---|---
find | body, observer, time | Find the position of body looking from observer at time
observe | body, observer, time | Find position of body adjusted for light-time
status | | Returns constants from loaded epehmeris file and status

Planets
-------
node-ephem provides a convenient name to code mapping via exported constants

Planet | Code
--- | ---
ephem.bodies.MERCURY | 1
ephem.bodies.VENUS | 2
ephem.bodies.EARTH | 3
ephem.bodies.MARS | 4
ephem.bodies.JUPITER | 5
ephem.bodies.SATURN | 6
ephem.bodies.URANUS | 7
ephem.bodies.NEPTUNE | 8
ephem.bodies.PLUTO | 9
ephem.bodies.MOON | 10
ephem.bodies.SUN | 11

Testrunner
----------

A testrunner is included which executes the test files available for DE files. Download the testpo file and place in the same directory as the ephemeris file, then run:

```
node testrunner.js
```

Follow the instructions.

---
_Source: https://npm.io/package/node-ephem · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._