|OAS - Osservatorio Astronomico Sormano|
|OAS > MBPL - Minor Body Priority List ( Asteroids with H < = 22.0 or greater than 240 mt in diameter )|
Last update: June 26, 2016
Computations by: Francesco Manca , Piero Sicoli , Augusto Testa (email@example.com).
This list includes selected objects for which observations and/or identifications are most desirable, because hazardous close encounters with our planet could be predicted or at least (taking into account the present uncertainty of orbital elements) cannot be entirely ruled out (over a timespan of the order of one hundred years). For this reason we do not take into account here bodies having very accurate orbital parameters and a value of Earth MOID (Minimum Orbital Intersection Distance) larger than a given threshold, sufficient for excluding the possibility of very close approaches in the next future.
For all the entries, Earth MOID (software by F. Manca , G. Matarazzo , P. Sicoli , Sormano Observatory , see internal report N.50, 1996 ) and encounter parameters (software by A. Testa , Sormano Observatory) are computed again at each orbit update ( bold-type for MOID <=0.015 AU ).
A similar list for objects of smaller size (H > 22.0 or up to 240 mt in diameter) (see SAEL - Small Asteroids Encounters List) and a list of close approaches of comets to planets Mercury, Venus, Earth and Mars ( CCEL - List of Cometary Close Encounters ) are also available
In order to measure the uncertainty of the orbital elements we use the uncertainty number U adopted by the Minor Planet Center (see MPC 24597 and the related page about the U value). As a rule of thumb, we consider as potentially dangerous the bodies (<=22 or greater than 240 mt in diameter) having an Earth MOID distance lower than the following thresholds (as a function of U ):
Uncertainty Earth MOID limit number (AU) Asteroids: 7<= U 0.060 5<= U <= 6 0.045 3<= U <= 4 0.030 0<= U <= 2 0.015 Comets: see CCEL - List of Cometary Close Encounters
to planets Mercury, Venus, Earth and Mars
Predicted close encounters with the Earth are computed only for bodies having sufficiently good orbital elements ( namely, objects for which the U parameter is lower or equal to 5 ): the most interesting approaches are listed in the following table (truncation of date is applied) , anyway in presence of a small error on the nominal distance and low MOID, the run has been carried out well beyond this limit of time. Moreover, a further integration for one hundred years in the past is intended to stimulate pre-discovery searches on old plates.
For the most interesting close encounters (depending on MOID, U parameter, nominal distance, propagation of the error etc.) the future minimum (min) and maximum (max) miss distances in AU are computed using the OrbFit Software Package ( F. Manca). These values, based on a 3-sigma uncertainty confidence level, are reported at the left of the nominal result and a symbol " r " means that available radar observations have been included in the orbital solution.
In addition, for objects having low accuracy orbits (U parameter >= 6) and a MOID smaller than 0.015 AU, we report the circumstances of the encounter in italic and within
< angle brackets >
The list could be a support for observing and research plans.
Any comment and/or suggestion will be welcomed.
For related information, see also:
Close Encounters and Selected Objects lists:
The following service, courtesy of the Minor Planet
Center, is intended as support and in addition to the objects available in the MBPL list for which follow-up or recovery is needed.
The service will return all objects (NEOs and Comets) based on criteria specified by the user and
NOT filtered in relation to their MOID value or PHA status.
Astrometric observations of any of the following objects should be sent directly