• MPC Preparation (Info)

  • MPChecker: Minor Planet Checker

    Use the form below to prepare a list of known minor planets in a specified region. Notes on using this form are given at the bottom of this page.

    The data behind MPChecker is updated daily. Objects observed within the past day may have ephemerides that are out-of-date.

    If you wish to report the non-functioning of (or errors in) this service, please use this feedback form. But ensure that you have seen the note on computing limits at the bottom of this page before reporting anything.

    Date : UT

    Produce list of known minor planets around:

    this J2000.0 position: R.A. = Decl. =

    or around these observations:

    Radius of search = arc-minutes

    Limiting magnitude, V =   Observatory code =

    Output matches in order of:

    increasing distance from specified position    increasing Right Ascension

    Display motions in arcseconds per minute or hour
    or degrees per day
    Display total or separate motions

    Output designations in unpacked or packed form

    all objects
    just those flagged as needing observations
    just numbered objects
    just unnumbered objects
    just those nearly-numberable unnumbered objects

    Return: plain HTML page or MPES-aware HTML page

    Useful Tips

    We hope that the information given below will be useful in helping you to use the minor-planet checker form properly.
    The date to be entered is the UT date of your observation (given to 0.1 or 0.01 of a day). The default is now.

    This form is now useable for dates back to 1800, with the following restrictions: for dates before 1900, only the first 500 numbered minor planets are included and comparisons are done using elements at the nearest 200-day epoch; for dates between 1900 and 2009, the comparisons are done using elements at the nearest 200-day epoch, but all numbered and perturbed unnumbered objects are included (these files are updated monthly); and for more recent dates, all objects are included (including comets) and comparisons are done using elements at the nearest 40-day epoch (or the nearest 1-day epoch for very recent dates).

    The determination of which epoch-element file to use is based on the date of the first observation (if specifying observations). When checking NEO candidates (for speed, use one of the other MPChecker forms geared towards NEOs) it is recommended that all observations in a single request are within +/- 0.5 days of a 0h UTC date. The form will work if the observations cover a greater range of dates, but positional accuracy will degrade as observation dates move away from the first observation date.

    Absolute Position
    The J2000.0 right ascension should be entered in one of the following forms: HH MM; HH MM.d; HH MM.dd; HH MM SS; HH MM SS.d; or HH MM SS.dd. HH represents the hours, MM the minutes, SS the seconds and d/dd any decimal part of the minutes or seconds. Leading zeroes are to be given when any quantity is less than 10.

    The J2000.0 declination should be entered in one of the following forms: sDD MM; sDD MM.d; sDD MM.dd; sDD MM SS; or sDD MM SS.d. s represents the sign (`+' or `-', must be given), DD the degrees, MM the minutes, SS the seconds and d/dd any decimal part of the minutes or seconds. Leading zeroes are to be given when any quantity is less than 10.

    Some examples of valid input follow.

    • If the position you wish to search around is 7h13.7m, -14°2', you would enter `07 13.7' and `-14 02' in the relevant boxes
    • If the position is 14h3m8s, +1°48'.3, you would enter `14 03 08' and `+01 48.3'.

    One or more 80-column observation records can be typed or pasted into the writable icon. The date of the search, central position and observatory code will be taken from the observation record. Multiple observations of the same object will be reduced to a single observation. If you are entering search fields, rather than observations, ensure that each search field has a unique "designation".

    Radius of search
    The default setting of 15 arcminutes is thought to be appropriate for the standard amateur setup, considering the motion of main-belt asteroids. It may be lowered (down to 5 arcminutes) or raised (up to 300 arcminutes) as desired. If your specified radius exceeds the maximum allowable radius, the maximum value will be used.

    Limiting magnitude for search
    The default setting of V = 20.0 may be changed as necessary. Note that you should set this value to be at least 1.0 magnitude fainter than your telescope's limiting magnitude to allow for poorly-known minor-planet magnitudes.

    Observatory code
    By default, the calculation is performed for the geocenter (code 500). If you wish to do the calculations for a specific site, enter the appropriate observatory code in the writable icon.

    By default all types of objects are searched for. By selecting other options you can restrict the search to just numbered or unnumbered minor planets or nearly-numberable minor planets. If this latter option is chosen, the maximum search radius is 900 arcminutes. It is important to remember when using the nearly-numberable option that the vast majority of the nearly-numberable objects are in fact numbered in the next batch of MPCs. This means that in the period immediately after MPC preparation there may be very few objects selected.

    Computing Limits
    Note that this form is not intended for checking large number of fields. There is a maximum limit for CPU time associated with this script. It this limit is exceeded, the job will be aborted. This prevents a handful of users running long lists of checks from clogging up the web server for other users. It is far more efficient to submit large batches of unidentified observations to the MPC for automatic processing than it is to try and id the objects through this service.