Detection of a Faint Fast-Moving Near-Earth Asteroid Using the Synthetic Tracking Technique

Abstract

We report a detection of a faint near-Earth asteroid (NEA), which was done using our synthetic tracking technique and the CHIMERA instrument on the Palomar 200-inch telescope. This asteroid, with apparent magnitude of 23, was moving at 5.97 degrees per day and was detected at a signal-to-noise ratio (SNR) of 15 using 30 sec of data taken at a 16.7 Hz frame rate. The detection was confirmed by a second observation one hour later at the same SNR. The asteroid moved 7 arcseconds in sky over the 30 sec of integration time because of its high proper motion. The synthetic tracking using 16.7 Hz frames avoided the trailing loss suffered by conventional techniques relying on 30-sec exposure, which would degrade the surface brightness of image on CCD to an approximate magnitude of 25. This detection was a result of our 12-hour blind search conducted on the Palomar 200-inch telescope over two nights on September 11 and 12, 2013 scanning twice over six 5.0 • ×0.043 • fields. The fact that we detected only one NEA, is consistent with Harris's estimation of the asteroid populationdistribution, which was used to predict the detection of 1-2 asteroids of absolute magnitude H=28-31 per night. The design of experiment, data analysis method, and algorithms for estimating astrometry are presented. We also demonstrate a milli-arcsecond astrometry using observations of two bright asteroids with the same system on Apr 3, 2013. Strategies of scheduling observations to detect small and fast-moving NEAs with the synthetic tracking technique are discussed.

CHIMERA: a wide-field, multi-colour, high-speed photometer at the prime focus of the Hale telescope

“…The limiting magnitude for CHIMERA is ∼27 mag (see Section 6), and thus the expected yield for NEA observations with CHIMERA is predicted to be 8 NEAs (<10 m, H = 28 mag) and 20 (H>25 mag) per night, with sizes down to 7 m, which dwarfs the total global yield of 30 NEAs yr −1 for H>28 mag. This prediction has already been demonstrated with the detection of one new low mass NEA with a diameter of 8 m and H = 29 mag with an early prototype version of the CHIMERA instrument Zhai et al 2014).…”

Space Object Detection in Images Using Matched Filter Bank and Bayesian Update

“…The desired partitioning will, however, be occurring on orbits which exist as elements in R 6 . The MDM can also be defined over a set of orbits because of the onto mapping from orbits to measurement arcs, Equation (18). This can also be shown by acknowledging thatρ a (t) is a function of x(t).…”

“…While this paper focuses on matched filters as an SNR optimal technique, there are a multitude of methods for detecting and tracking low SNR space objects. Examples include multi-object filtering [15], multiple hypothesis testing [16], multi-frame matched filters [9], Track-Before-Detect, [17], Shift and add methods [18], and more. All of these methods, when applied to SSA images, rely on determining how an object moves through the sky around a certain observer.…”

Accurate Ground-based Near-Earth-Asteroid Astrometry Using Synthetic Tracking

“…While the impact of a big asteroid could have catastrophic consequences, in view of the damage caused by the incident of the Chelyabinsk meteor (Brumfiel 2013) and the fact that the frequency for smaller asteroids to impact Earth is much higher than that of larger asteroids (NRC 2010), it is important to watch for any potential threats from asteroids larger than 10 m. Larger asteroids are brighter and thus easier to detect. To efficiently detect small asteroids, we have developed the synthetic tracking (ST) technique that replaces long exposure images with multiple short-exposure images and integrates the images in postprocessing to detect faint asteroids Zhai et al 2014). ST is enabled by the modern sCMOS cameras that can take megapixel frames at rate faster than 10 Hz yet only introduce low read noise at 1-2e − per read.…”