Statistical analysis of the astrometric errors for the most productive asteroid surveys
Abstract
Accurate orbits of minor planets allow reliable predictions of an object's location in time and space. High fidelity ephemerides are crucial for the space missions targeting asteroids and comets, mitigation of Earth impact hazard, study of non-gravitational effects on small bodies and mass determination of encountering objects through mutual perturbations. The length of the observation arc as well as high quality astrometry play an essential role in achieving accurate orbits. In particular, accurate astrometry can allow the recovery of small near-Earth objects that could otherwise be lost. The vast majority of the 715,000 known asteroids have been discovered and observed by major dedicated optical CCD surveys. However, uncertainties of individual astrometric positions are not directly provided by observers yet and so orbit determination traditionally relies on conservative estimates of astrometric errors. We present a statistical study of astrometric residuals of optical CCD astrometry for the nine most prolific past and current asteroid surveys: Pan-STARRS1 (F51), Mt. Lemmon (G96), Catalina (703), LINEAR (704), Spacewatch (691), LONEOS (699), NEAT (644), NEOWISE (C51) and SST (G45). The study was limited to multiple apparition asteroids, which have well-constrained orbits, after correcting for the star catalog position and proper motion biases (Farnocchia et al., 2015). Therefore, the resulting astrometric residuals can be largely attributed to astrometric and timing errors in the reported astrometry. We analyze the behavior of residuals in right ascension, declination, along-track and cross-track, as well as timing errors. Astrometric residuals generally depend on reported magnitude by a quadratic function with astrometric quality degradation near the limiting magnitude and the saturation limit for bright objects. We found no systematic timing errors exceeding one second for the tested surveys. The presented analysis provides useful information to improve the data-weighting schemes and, more in general, the statistical treatment of astrometric observations and to compute more accurate asteroid orbits.Copyright 2016 California Institute of Technology. U.S. Government sponsorship acknowledged.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #48
- Pub Date:
- October 2016
- Bibcode:
- 2016DPS....4832713V