Tracking non-sidereal objects

Stars are cool, but they don't move much. At least they don't move much as viewed from here on earth (once you deal with the nasty business of the earth's rotation).

Other sorts of objects can provide a new level of excitement. These are typically solar system objects (planets, asteroids and such), and earth orbiting objects such as earth launched satellites and earth orbiting debris. (There is always the moon, but it is mostly just a nuisance being so big and bright)

General references

Objects with heliocentric orbits (things that go 'round the sun)

For planets, you can use planets.edb at the MMT to access "built in" code in the mmt mount to calculate planetary positions. Alternately, use the JPL Horizons system to obtain accurate and up to date ephemerides.

Asteroids, in particular, require up to date ephemerides. The edb files mentioned above have static information (Keplerian elements), that can only expected to be accurate for a few weeks. All bets are off if the asteroid in question passes close to a large body.

Good places to go for up to date coordinates are:

The Lowell Database (43082 orbits) (a 31 megabyte download) is 115 megabytes when downloaded and uncompressed. It is based on information from the Harvard Minor Planet Center, but orbital calculations are performed at Lowell. They update their data daily. Usually by 10:00 UT (3 AM MST), but on the date of the full moon, expect this to be about 4 hours later! Using the URL is the most straightforward scheme here to get this data. The Minor Planet Center at Harvard CFA offers the MPC Orbit database for free download by anonymous ftp via the link: (MPCORB.ZIP is 22.1 megabytes and expands to 74 megabytes - as of late 2008).

The Jet Propulsion Laboratory (JPL) at the California Institute of Technology has an extensive database of solar system objects. At the time of this writing they claim 430660 asteroids, 2966 comets, 168 planetary satellites, and more. They do not provide a database for download, but rather an interface to query their database and obtain information via several interfaces.

Satellites and Satellite tracking.

Just for fun, the following site has lots of information about informal visual observation of satellites: The Visual Satellite Observer's Home Page. Also, the
  • Heavens Above site has lots of up to date information about satellites, iridium flares, and other "current events" in the skys above. In this vein, don't neglect the
  • Sky and Telescope "week at a glance"

    Earth orbiting satellites have orbits that are typically described by "two line element" TLE data files.

    Celestrak is public. Space Track is restricted to approved and registered users (and holds 68,570,045 objects as of this writing in late 2008).


    The following is a short set of links to relevant software: