International Space Station Current Location

The International Space Station is moving at close to 28,000 km/h so its location changes really fast! Where is it right now?

Overview

This is a simple api to return the current location of the ISS. It returns the current latitude and longitude of the space station with a unix timestamp for the time the location was valid. This API takes no inputs.

Output

JSON

http://api.open-notify.org/iss-now.json

{
  "message": "success", 
  "timestamp": UNIX_TIME_STAMP, 
  "iss_position": {
    "latitude": CURRENT_LATITUDE, 
    "longitude": CURRENT_LONGITUDE
  }
}

The data payload has a timestamp and an iss_position object with the latitude and longitude.

JSONP

Appending a callback request to the query string will return JSONP:

http://api.open-notify.org/iss-now.json?callback=CALLBACK

CALLBACK({
  "message": "success", 
  "timestamp": UNIX_TIME_STAMP,
  "iss_position": {
    "latitude": CURRENT_LATITUDE, 
    "longitude": CURRENT_LONGITUDE
  }
})

Poll Rate

Please note that there is an inherent uncertainty in the ISS position models that is usually larger than one second. In addition the position is only calculated once per second (the maximum resolution of an integer unix time stamp). So polling more than 1 Hz would be useless except to add unnessisary strain to the servers.

A single client should try and keep polling to about once every 5 seconds.

Examples

Here is an example reading the API in python:

import urllib2
import json

req = urllib2.Request("http://api.open-notify.org/iss-now.json")
response = urllib2.urlopen(req)

obj = json.loads(response.read())

print obj['timestamp']
print obj['iss_position']['latitude'], obj['data']['iss_position']['latitude']

# Example prints:
#   1364795862
#   -47.36999493 151.738540034

Data Source

The ISS is tracked by several agencys. Both NORAD and NASA periodically publish data about the station. I scrape this page for this API:

http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html

Another popular site for tacking data is celstrak which published NORAD TLE’s:

http://www.celestrak.com/NORAD/elements/stations.txt

In both cases a “Two Line Element” is used, which contains enough infomation about an orbit to calculate an objects postition at any time within a useful window of accuracy centered around the TLE’s publish date. I try to update the TLE at least once a day.

Open Notify