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EURONEAR - recovery, follow-up and discovery of NEAs and MBAs using large field 1-2 m telescopes O. Vaduvescu et al.
Planet. Space Sci., 59, 1632-1646 (2011)
Abstract:
We report on the follow-up and recovery of 100 program NEAs, PHAs and VIs
using the ESO/MPG 2.2 m, Swope 1 m and INT 2.5 m telescopes equipped with
large field cameras. The 127 fields observed during 11 nights covered 29
square degrees. Using these data, we present the incidental survey work
which includes 558 known MBAs and 628 unknown moving objects mostly
consistent with MBAs from which 58 objects became official discoveries. We
planned the runs using six criteria and four servers which focus mostly on
faint and poorly observed objects in need of confirmation, follow-up and
recovery. We followed 62 faint NEAs within one month after discovery and we
recovered 10 faint NEAs having big uncertainties at their second or later
opposition. Using the INT we eliminated four PHA candidates and VIs. We
observed in total 1286 moving objects and we reported more than 10,000
positions. All data were reduced by the members of our network in a team
effort, and reported promptly to the MPC. The positions of the program NEAs
were published in 27 MPC and MPEC references and used to improve their
orbits. The O-C residuals for known MBAs and program NEAs are smallest for
the ESO/MPG and Swope and about four times larger for the INT whose field is
more distorted. For the astrometric reduction, the UCAC-2 catalog is
recommended instead of USNO-B1. The incidental survey allowed us to study
statistics of the MBA and NEA populations observable today with 1-2 m
facilities. We calculate preliminary orbits for all unknown objects,
classifying them as official discoveries, later identifications and unknown
outstanding objects. The orbital elements a, e, i calculated by FIND_ORB
software for the official discoveries and later identified objects are very
similar with the published elements which take into account longer
observational arcs; thus preliminary orbits were used in statistics for the
whole unknown dataset. We present a basic model which can be used to
distinguish between MBAs and potential NEAs in any sky survey. Based on
three evaluation methods, most of our unknown objects are consistent with
MBAs, while up to 16 unknown objects could represent NEO candidates and four
represent our best NEO candidates. We assessed the observability of the
unknown MBA and NEA populations using 1 and 2 m surveys. Employing a 1 m
facility, one can observe today fewer unknown objects than known MBAs and
very few new NEOs. Using a 2 m facility, a slightly larger number of unknown
than known asteroids could be detected in the main belt. Between 0.1 and 0.8
new NEO candidates per square degree could be discovered using a 2 m
telescope.