• MPC Preparation (Info)

  • Comments and Notes on the NEOCP

    The NEOCP gives access to ephemerides for newly-discovered fast-moving (or other unusual) objects in need of confirmation. Most of the objects listed here have not yet received official provisional designations from the Minor Planet Center, such objects are referenced by their observer-assigned temporary designations.

    These temporary designations and ephemerides must not be promulgated.

    In light of the recent increase in comet discoveries, many of which have appeared initially on this NEO Confirmation Page, there is a need for accurate astrometry between the time the object appears on an IAUC (and is hence removed from the Confirmation Page) and the time that the first orbit is published. The Confirmation Page has now been extended so that observers may continue to get ephemerides for newly-discovered comets without published orbits.

    • If possible, observations should be made over an arc of several hours during the course of at least one night.
    • When local circumstances are displayed, the azimuths are reckoned westwards from the south meridian.
    • Ephemerides are in Universal Time (UT).
    • Ephemerides can be generated for the geocenter, for a specific observatory code or for a user-specified site on the earth.
    • For single-nighters, uncertainty maps and/or tables of offsets can be generated.
      The uncertainty maps include an indication of objects that are close to the earth. Three colors are used to indicate objects at various distances:
      • green, for objects that are more then 0.05 AU from the earth at the time used for the uncertainty map;
        • Further classifications are made as follows:
        • dark blue, for orbits that are "main-belt"
        • magenta, for orbits that are Jupiter Trojans [this is not currently implemented, at the present time such orbits are colored dark blue]
      • orange (supposedly) for objects between 0.05 and 0.01 AU from the earth
      • red, for objects within 0.01 AU.
      On the list of offset coordinates, variant ephemeris positions that are orange on the map are flagged by "!" and positions that are red on the map are flagged by "!!".
      In addition, the NEOCP now flags those variant orbits that will be coming within 0.0027 AU (roughly one lunar distance) sometime in the next 100 hours. Such objects will be shown in black on the uncertainty maps and flagged with "***" on the lists of offset coordinates.
      Counts of the number of variant orbits in each of the four flagged categories are now displayed to the right of the uncertainty plot.
    • Potentially very small objects (with H fainter than 22.0) are indicated for the benefit of photometric observers by inclusion of an asterisk in the summary line on the main NEOCP pages and in the ephemeris header line between `U.T.' and `R.A.'.
    • When observer comments are displayed, the column marked 'ONS' indicates whether or not the object was a one-nighter at the time the comment was submitted.
    • When a removed object is flagged as `does not exist', it means that the object was retracted by the observer. If flagged as `lost', it means that either the object exists but was not confirmed, or that it does not exist. Presumably some sizeable fraction of the objects flagged as `lost' are really 'does not exist' cases.

    Removal of Objects

    • Objects are removed from the NEOCP when they meet any of the following criteria:
      1. There is sufficient astrometry to determine a well-constrained orbit and the object is believed to be new. In this scenario, the object is designated and its orbit published. If the object is either an NEO or a distant object (q > 5.6 AU), the discovery is announced in an MPEC.
        In most cases, NEOCP objects are designated and an MPEC is issued (if applicable) manually. However, an automated script also runs which is able to automatically handle the easy cases. This script runs several times per day and will only designate an NEOCP object if it meets all of the following conditions:
        1. Has at least a one day arc
        2. Has at least 10 observations
        3. Variant orbits are all either NEOs or are all non-NEOs. (i.e. straddling the boundary is not allowed)
        4. The perihelion distance is < 5.6 au (distant objects are not automated)
        5. The astrometry is from at least two different observatory codes, in at least three different submissions
        6. The object is not flagged as being a suspected artificial satellite or comet
        7. There are at least three photometric measurements
        8. There are no near-duplicate observations that are found in our database
        9. A well-constrained and non-degenerate orbit can be fit
        10. The fitted orbit has an associated H-magnitude
        11. The fraction of observations used in the orbit fit is > 85% (i.e. less than 15% are rejected from the fit)
        12. The orbit fit does not produce suspicious-looking residuals. This includes residuals > 2" that have not been excluded from the orbit fit, residuals < 1" that have been excluded from the orbit fit, as well as tracklets where half or more of the tracklet has been excluded from the orbit fit
        13. No additional observations (ITF or known object) with appropriate rates of motion are found anywhere along the predicted ephemeris track
        14. No known object is predicted to be nearby at the time of the observations
        15. The object is not a virtual impactor
        16. The Earth MOID is > 2 Earth radii and no close approaches within 5 radii of the Earth in the 21st century
        17. Creating the new designation will not exceed the packed-designation limit in a given half-month
        18. Additional minor fail-safe checks all pass
        Once designated, the automated script will generate an MPEC if the object is an NEO, or simply remove the object from the NEOCP if it is not.
      2. Objects on the PCCP are designated as a new comet if the orbit is well-constrained and there are at least 2 independent positive reports of its cometary nature. The discovery is announced in an MPEC. Objects with cometary-like orbits with negative reports are designated as minor planets.
      3. If the object on the NEOCP is identified with a known object, an MPEC is issued if the object represents the recovery of an NEO on its second apparition.
      4. If the object on the NEOCP is identified as being artificial it will be removed and flagged as 'not a minor planet'.
      5. If the object on the NEOCP can be considered to be submitted by mistake, e.g. not being real or retracted by observers, in that case the object is removed as 'does not exist'.
      6. If the object on the NEOCP is linked to another NEOCP object.
      7. If the object on the NEOCP cannot be identified with a known object nor designated as a new object (due to lack of astrometry and inability to compute a well constrained orbit) the object is removed as 'was not confirmed'. The object will be removed automatically when the following criteria are satisfied (N.B. These rules do not apply to PCCP objects):
        1. The object has been on NEOCP >= 5 days
        2. The object's observation arc is short (<0.833 day)
        3. There is no positive cometary activity report filed for the object and one of the following conditions is met:
          1. The object becomes too faint (the median V-band magnitude of its variant orbits at the current epoch is > 24.5)
          2. The object is too close to the Sun (solar elongation of the nominal orbit at the current epoch < 30 deg)
          3. The object's lifetime on the NEOCP >= 20 days
          4. The object's on-sky uncertainty becomes large according to the following criteria that are dependent on apparent magnitude (V):
            • V < 18 and 1-sigma uncertainty > 30 deg
            • V >= 18 and V < 20 and 1-sigma uncertainty > 10 deg
            • V >= 20 and V < 22 and 1-sigma uncertainty > 5 deg
            • V >= 22 and V < 24.5 and 1-sigma uncertainty > 3 deg
            • V > 24.5
        4. If B. is not satisfied (the object's arc length is > 0.833 day) but the orbit remains unconstrained (i.e. due to insufficient astrometry), then the object can reside on the NEOCP for >20 days and would be removed manually (as 'not a minor planet').
    • Dispositions of NEOCP objects at the time of removal are listed on the Previous NEO Confirmation Page. Also, reasons for removal if no designation was assigned are explained here.