Abstract
Abstract Accurate astrometry is crucial for determining orbits of near-Earth-asteroids (NEAs) and therefore better tracking them. This paper reports on a demonstration of 10 mas level astrometric precision on a dozen NEAs using the Pomona College 40 inch telescope, at the JPL’s Table Mountain Facility. We used the technique of synthetic tracking (ST), in which many short-exposure (1 s) images are acquired and then combined in post-processing to track both target asteroid and reference stars across the field of view. This technique avoids the trailing loss and keeps the jitter effects from atmosphere and telescope pointing common between the asteroid and reference stars, resulting in higher astrometric precision than the 100 mas level astrometry from traditional approach of using long exposure images. Treating our ST of near-Earth asteroids as a proxy for observations of future spacecraft while they are downlinking data via their high rate optical communication laser beams, our approach shows precision plane-of-sky measurements can be obtained by the optical ground terminals for navigation. We also discuss how future data releases from the Gaia mission can improve our results.
Highlights
Near-Earth-Asteroid (NEA) observations and characterization is crucial for protecting our planet
The location and velocity (vx, vy) are solved simultaneously using a least-squares fitting together with parameters α and I0, which give photometry and background intensity. We note that this approach to integrate a data cube avoids streaked images and keeps the jitter effect from atmosphere and telescope pointing common between target and reference objects, achieves accuracy comparable with stellar astrometry, which we shall present in subsection 4.1
Synthetic tracking avoids streaked images by having exposures short enough so that the moving object does not streak in individual images,4 allowing us to achieve astrometry similar to stellar astrometry for NEAs
Summary
Near-Earth-Asteroid (NEA) observations and characterization is crucial for protecting our planet. We can achieve astrometry accuracy for NEAs comparable to stellar astrometry because we can track both the NEAs and reference stars in post-processing; the target and reference objects can be treated the same way. This is significant in view of that ground-based stellar astrometry was able to reach 1 mas accuracy more than a decade ago(Pravdo and Shaklan 2004; Henry et al 2009). This paper reports our method and results from our instrument using synthetic tracking and Gaia DR1 catalog to demonstrate the potential of achieving accuracy for NEA astrometry much higher than the current state-of-the-art of 120 mas from Pan-STARRS survey telescope (Veres et al 2017)
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