Small Near-Earth Asteroids in the Palomar Transient Factory Survey: A Real-Time Streak-detection System

March 2017 • 2017PASP..129c4402W

Authors • Waszczak, Adam • Prince, Thomas A. • Laher, Russ • Masci, Frank • Bue, Brian • Rebbapragada, Umaa • Barlow, Tom • Surace, Jason • Helou, George • Kulkarni, Shrinivas

Abstract • Near-Earth asteroids (NEAs) in the 1-100 meter size range are estimated to be ∼1,000 times more numerous than the ∼15,000 currently cataloged NEAs, most of which are in the 0.5-10 kilometer size range. Impacts from 10-100 meter size NEAs are not statistically life-threatening, but may cause significant regional damage, while 1-10 meter size NEAs with low velocities relative to Earth are compelling targets for space missions. We describe the implementation and initial results of a real-time NEA-discovery system specialized for the detection of small, high angular rate (visually streaked) NEAs in Palomar Transient Factory (PTF) images. PTF is a 1.2-m aperture, 7.3 deg² field of view (FOV) optical survey designed primarily for the discovery of extragalactic transients (e.g., supernovae) in 60-second exposures reaching ∼20.5 visual magnitude. Our real-time NEA discovery pipeline uses a machine-learned classifier to filter a large number of false-positive streak detections, permitting a human scanner to efficiently and remotely identify real asteroid streaks during the night. Upon recognition of a streaked NEA detection (typically within an hour of the discovery exposure), the scanner triggers follow-up with the same telescope and posts the observations to the Minor Planet Center for worldwide confirmation. We describe our 11 initial confirmed discoveries, all small NEAs that passed 0.3-15 lunar distances from Earth. Lastly, we derive useful scaling laws for comparing streaked-NEA-detection capabilities of different surveys as a function of their hardware and survey-pattern characteristics. This work most directly informs estimates of the streak-detection capabilities of the Zwicky Transient Facility (ZTF, planned to succeed PTF in 2017), which will apply PTF’s current resolution and sensitivity over a 47-deg² FOV.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2017PASP..129c4402W
• PDF https://iopscience.iop.org/article/10.1088/1538-3873/129/973/034402/pdf
• PDF https://iopscience.iop.org/article/http://iopscience.iop.org/article/10.1088/1538-3873/129/973/034402/pdf
• PREPRINT http://arxiv.org/abs/1609.08018
• ELECTR http://iopscience.iop.org/article/10.1088/1538-3873/129/973/034402
• ELECTR https://iopscience.iop.org/article/10.1088/1538-3873/129/973/034402