Unconfirmed Near-Earth Objects

Abstract

We studied the Near-Earth Asteroid (NEA) candidates posted on the Minor Planet Center's Near-Earth Object Confirmation Page (NEOCP) between years 2013 and 2016. Out of more than 17,000 NEA candidates, while the majority became either new discoveries or were associated with previously known objects, about 11% were unable to be followed-up or confirmed. We further demonstrate that of the unconfirmed candidates, 926 ± 50 are likely to be NEAs, representing 18% of discovered NEAs in that period. Only 11% (∼ 93) of the unconfirmed NEA candidates were large (having absolute magnitude H < 22). To identify the reasons why these NEAs were not recovered, we analyzed those from the most prolific asteroid surveys: Pan-STARRS, the Catalina Sky Survey, the Dark Energy Survey, and the Space Surveillance Telescope. We examined the influence of plane-of-sky positions and rates of motion, brightnesses, submission delays, and computed absolute magnitudes, as well as correlations with the phase of the moon and seasonal effects. We find that delayed submission of newly discovered NEA candidate to the NEOCP drove a large fraction of the unconfirmed NEA candidates. A high rate of motion was another significant contributing factor. We suggest that prompt submission of suspected NEA discoveries and rapid response to fast moving targets and targets with fast growing ephemeris uncertainty would allow better coordination among dedicated 2 Vereš et al.follow-up observers, decrease the number of unconfirmed NEA candidates, and increase the discovery rate of NEAs.

High-fidelity Simulations of the Near-Earth Object Search Performance of the Large Synoptic Survey Telescope

“…We find that C H<22 55 ± 5% for the baseline minion_1016 survey operating alone and with the linking working at 93.6% efficiency (Vereš & Chesley 2017). This result assumes 12-day, 3-night tracks, and accounts for all of the foregoing modeling features and sources of error, including linking losses.…”

“…Accounting for the linking losses and bright source masking assumed by Vereš & Chesley (2017), we lose another 4.4%, arriving at a final C H<22 estimate of 54.6%.…”

“…• Linking efficiency is discussed at length by Vereš & Chesley (2017). Here we assume a value of 93.6 +6 −1 %.…”

“…In particular, two-night orbits are generally uncertain enough that MBAs and NEOs cannot be distinguished in general. As discussed by Vereš & Chesley (2017), this is already an issue for some three-night orbits, but for two-night orbits it is the norm. Table 9 indicates the level of NEO completeness that would be obtained for the four-visit enigma_1266 survey, assuming that a minimum of either three or four detections are available for each tracklet.…”

“…Thus, our work assumes that the linking to orbits will work on the available collection of tracks. In a separate paper (Vereš & Chesley 2017), we consider the linking efficiency problem for LSST with MOPS.…”