tle
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Two-line element set (TLE) data format parser
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# Two-line element set (TLE)
[](https://npmjs.com/package/tle)
[](https://npmjs.com/package/tle)
[](https://npmjs.com/package/tle)
Two-line element set (TLE) data format parser
A two-line element set ([TLE]) is a data format used to convey sets of orbital elements that describe the orbits of Earth-orbiting satellites. A computer program called a model can use the TLE to compute the position of a satellite at a particular time. The TLE is a format specified by NORAD and used by [NORAD] and [NASA]. The TLE can be used directly by the [SGP4] model (or one of the SGP8, [SDP4], SDP8 models). Orbital elements are determined for many thousands of space objects by NORAD and are freely distributed on the Internet in the form of TLEs. A TLE consists of a title line followed by two lines of formatted text.
— From [Wikipedia](https://en.wikipedia.org/wiki/Two-line_element_set)
[TLE]: https://en.wikipedia.org/wiki/Two-line_element_set
[NORAD]: https://en.wikipedia.org/wiki/NORAD
[NASA]: https://en.wikipedia.org/wiki/NASA
[SGP4]: https://en.wikipedia.org/wiki/SGP4
[SDP4]: https://en.wikipedia.org/wiki/SDP4
## Install via [npm](https://npmjs.com/package/tle)
```sh
$ npm install --save tle
```
## Format
**More, detailed information is available at [NASA Human Space Flight](https://web.archive.org/web/20200609193115/https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/SSOP_Help/tle_def.html):**
<h3 align="center">
<a href="https://web.archive.org/web/20200609193115/https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/SSOP_Help/tle_def.html">
<img alt="Definition of Two-line Element Set Coordinate System" src="./doc/2line.gif">
</a>
</h3>
Some data to play around with can be found at [Celestrak](https://celestrak.org/NORAD/elements/).
## Usage
```js
var TLE = require( 'tle' )
```
### Parsing a single set
```js
var set = 'ISS (ZARYA)\n' +
'1 25544U 98067A 08264.51782528 -.00002182 00000-0 -11606-4 0 2927\n' +
'2 25544 51.6416 247.4627 0006703 130.5360 325.0288 15.72125391563537'
```
```js
var tle = TLE.parse( set )
```
```js
TLE {
name: 'ISS (ZARYA)',
number: 25544,
class: 'U',
id: '98067A',
date: Date<'2008-09-20T12:25:40.104Z'>,
fdmm: -0.00002182,
sdmm: 0,
drag: -0.000011606,
ephemeris: 0,
esn: 292,
inclination: 51.6416,
ascension: 247.4627,
eccentricity: 0.0006703,
perigee: 130.536,
anomaly: 325.0288,
motion: 15.72125391,
revolution: 56353,
}
```
### Parsing a stream
```js
var parser = new TLE.Parser( options ) // OR
var parser = TLE.createParser( options )
````
```js
fs.createReadStream( FILEPATH )
.pipe( new TLE.Parser() )
.on( 'data', function( tle ) {
// ...
})
```
### Creating a TLE instance from existing data
```js
// From a JSON string
var tle = TLE.fromJSON( '{"name":"ISS (ZARYA)","number":25544,"class":"U","id":"98067A","date":"2008-09-20T12:25:40.104Z","fdmm":-0.00002182,"sdmm":0,"drag":-0.000011606,"ephemeris":0,"esn":292,"inclination":51.6416,"ascension":247.4627,"eccentricity":0.0006703,"perigee":130.536,"anomaly":325.0288,"motion":15.72125391,"revolution":56353}' )
```
```js
// From an object
var tle = TLE.fromJSON({
name: 'FENGYUN 1C DEB',
class: 'U',
id: '29740',
})
```
## Speed
It can read, stream & parse ~2500 TLEs from the file system in about 100ms.
```
node example/fs-stream.js
Parser: 2517 TLEs, 108ms, 23306 op/s
Parser: 23 op/ms
```
## Examples
See `examples` folder for runnable examples:
```
node examples/fs-stream.js
node examples/http-stream.js
```