Small near-Earth asteroids in the Palomar Transient Factory survey: A real-time streak-detection system

Abstract

Near-Earth asteroids (NEAs) in the 1-100 meter size range are estimated to be $\sim$1,000 times more numerous than the $\sim$15,000 currently-catalogued NEAs, most of which are in the 0.5-10 kilometer size range. Impacts from 10-100 meter size NEAs are not statistically life-threatening but may cause significant regional damage, while 1-10 meter size NEAs with low velocities relative to Earth are compelling targets for space missions. We describe the implementation and initial results of a real-time NEA-discovery system specialized for the detection of small, high angular rate (visually-streaked) NEAs in Palomar Transient Factory (PTF) images. PTF is a 1.2-m aperture, 7.3-deg${}^2$ field-of-view optical survey designed primarily for the discovery of extragalactic transients (e.g., supernovae) in 60-second exposures reaching $\sim$20.5 visual magnitude. Our real-time NEA discovery pipeline uses a machine-learned classifier to filter a large number of false-positive streak detections, permitting a human scanner to efficiently and remotely identify real asteroid streaks during the night. Upon recognition of a streaked NEA detection (typically within an hour of the discovery exposure), the scanner triggers follow-up with the same telescope and posts the observations to the Minor Planet Center for worldwide confirmation. We describe our ten initial confirmed discoveries, all small NEAs that passed 0.3-15 lunar distances from Earth. Lastly, we derive useful scaling laws for comparing streaked-NEA-detection capabilities of different surveys as a function of their hardware and survey-pattern characteristics. This work most directly informs estimates of the streak-detection capabilities of the Zwicky Transient Facility (ZTF, planned to succeed PTF in 2017), which will apply PTF's current resolution and sensitivity over a 47-deg${}^2$ field-of-view.

Accepted 11-September-2016 to Publications of the Astronomical Society of the Pacific (PASP)

References in corpus (4)

• The IPAC Image Subtraction and Discovery Pipeline for the intermediate Palomar Transient Factory
• Ultra-Low Delta-v Objects and the Human Exploration of Asteroids
• Detecting Earth's Temporarily-Captured Natural Satellites - Minimoons
• 313 new asteroid rotation periods from Palomar Transient Factory observations

Cited by in corpus (11)

• The Zwicky Transient Facility: System Overview, Performance, and First Results
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Zwicky Transient Facility: Science Objectives
• Machine Learning for the Zwicky Transient Facility
• Prediscovery Observations and Orbit of Comet C/2017 K2 (PANSTARRS)
• Optical Transient Object Classification in Wide Field Small Aperture Telescopes with Neural Networks
• Towards Efficient Detection of Small Near-Earth Asteroids Using the Zwicky Transient Facility (ZTF)
• Automated Detection of Satellite Trails in Ground-Based Observations Using U-Net and Hough Transform
• Euclid: Identification of asteroid streaks in simulated images using StreakDet software
• The Umbrella software suite for automated asteroid detection
• Near Ultraviolet Transient Explorer (NUTEx): A CubeSat-Based NUV Imaging Payload for Transient Sky Surveys