logo On-line Find_Orb

Overview of tools for asteroid observers on this site

Updated 2020 May 06

Special note about interstellar objects such as C/2019 Q4 = 2I/Borisov and A/2017 U1 = 1I = ʻOumuamua

Use the form below to get orbital elements and ephemerides from astrometric observations.

Suggested quick start: Don't panic! Copy/paste your observations in the large text window below, and/or click on "Browse" to pick a file containing the astrometry, and/or enter an object name.

Click here if you're wondering how to get your observations into the correct format.

Feed it all of your observations. There is almost never any benefit in giving the program a subset.

Then click the "compute orbit and ephemerides" button. Usually, that'll be all you need to do. If it isn't, hit the back arrow and look a little more closely at your options (options documented here.) If you're still not getting things to work, contact me.

Click here if you just want orbital elements and/or ephemerides for an object, and don't have astrometry for it.

Here are a few hints that may be useful.

Note that the orbit will be computed from all observations, from all three possible sources (cut/pasted, uploaded, or from MPC data), whether their designations match or not. So you can mix-and-match the three input sources, if you have (for example) some new observations of an object already known to MPC.

This is a modified, simplified, non-interactive version of the Find_Orb program.

There are several other tools for asteroid observers on this site.

Cut/paste observations in the 80-column MPC format, PSV or XML ADES, or the AstDyS/NEODys .rwo format below. Don't worry about it if some other text is copied in as well; extra text will simply be disregarded.

And/or, you can upload a file containing the astrometry (to be combined with anything in the above text box.)

And/or, you can enter an object name, and Find_Orb will get the astrometry for it from the MPC (and combine it with anything from the file or text box) : (examples: 1997 XF11, 141P, Icarus, NEOCP designations)

Ephemeris starting date : UTC (Universal Time)

Number of steps : Step size :

MPC observatory code or lat/lon:

Faint limit on ephemeris output:

Ephemeris type:

State vectors
Cartesian coördinates
MPCORB elements
8-line elements
Close approaches

Observable ephemeris options (only used if 'Observables' is checked above):

Alt/az Radial velocity
Phase angle Phase angle bisector Heliocentric ecliptic coörds
Ground track Visibility indicator Topocentric ecliptic coörds
Suppress unobservables Show ephemeris uncertainties Computer-friendly ephems
Lunar elongation Lunar altitude Lunar azimuth
Sky brightness Sun altitude Sun azimuth
PsAng PsAMV PlAng
Galactic lat/lon Galactic confusion Constellation
Motions in RA and dec Total motion & position angle
SNR Exposure time

Element center:

Epoch of orbital elements : TT

Residual format :
0.01" precision
0.001" precision
Show time/cross-path residuals

Redact NEOCP astrometry: (check this box if you're going to redistribute the pseudo-MPEC)


JSON elements, observations, and residuals
JSON ephemerides
JSON combining both of the above