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  • This page is going to be deprecated on Monday Nov 20th, 2023.
    Please use MPChecker to prepare a list of known planets in a specified region.
    If you have any questions about this page, please open a Jira ticket.

    CMTChecker: Comet Checker

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

    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 this note on computing limits before reporting anything.

    Date : UT

    Produce list of known comets 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

    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 comet 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 in the past, but currently only for objects that are in the list of "observable" comets at the present time. The comparisons are done using elements at the nearest 40-day epoch back to 1946 and the nearest 1-day epoch for current dates.

    The determination of which epoch-element file to use is based on the date of the first observation (if specifying observations). When checking candidates, it is recommended that all observations in a single request are within +/- 20 days of the first observation 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.

    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.