Keeping Time with the Asteroids

Abstract

The Catalina Sky Survey (CSS) has discovered 5790 of 13,392 known near-Earth asteroids (as of writing), as well as tens of thousands from the main belt, and over 300 comets. Astrometric observations from the three CSS telescopes have contributed to computing the orbits of the great majority of the 700,000 known asteroids of all types. CSS remains the only NEO survey to have discovered asteroids prior to Earth impact.

The distinctive feature of CSS operations is near real-time reporting and follow-up of new discoveries. Minutes after an NEO is first detected, astrometry is submitted to the Minor Planet Center for posting on the NEO Confirmation Page providing targeting coordinates for observers around the world. Rapidly moving NEOs risk becoming lost again unless observed over a sufficient orbital arc; a good orbit solution is required for future study of any solar system object.

The engineering trade-offs are thus between tuning the observing parameters maximizing discoveries of new objects, optimizing time-tagged astrometric and photometric precision, and a workflow supporting both survey and follow-up observations. We will discuss an automated tool, AsteroidClock, which compares statistics for known asteroids in the field of view against measurements taken through the survey workflow. The ephemerides of previously discovered objects serve as ground truth to evaluate the many degrees of freedom inherent in tuning the survey’s discovery and astrometry algorithms. As the name implies, an inventory of asteroids in the field of view can also provide a unique time stamp.