PS1 Telescope Establishes Near-Earth Asteroid Discovery Record
Richard Wainscoat (left) and Marco Micheli study a near-Earth asteroid found on January 29. The asteroid is the roundish dot near Wainscoat’s finger. Photo by Karen Teramura.
The Pan-STARRS PS1 telescope on Haleakala, Maui, discovered 19 near-Earth asteroids on the night of January 29, the most asteroids discovered by one telescope on a single night. "This record number of discoveries shows that PS1 is the world’s most powerful telescope for this kind of study," said Nick Kaiser, head of the Pan-STARRS project. "NASA and the U.S. Air Force Research Laboratory’s support of this project illustrates how seriously they are taking the threat from near-Earth asteroids."
Because of recent improvements to software and in observational techniques, Kaiser suggested a time close to the February 1 new moon would be an opportune time to dedicate an entire night to assessing PS1’s ability to discover near-Earth objects (NEOs), especially those possibly hazardous to Earth. A plan called "NEO Demo Night" was formulated, and the night of January 29 was selected. Pan-STARRS software engineer Larry Denneau spent that Saturday night in his UH Manoa office in Honolulu processing the PS1 data as it was transmitted from the telescope over the Internet. During the night and into the next afternoon, he and others came up with 30 possible new near-Earth asteroids.
Asteroids are discovered because they appear to move against the background of stars. To confirm asteroid discoveries, scientists must carefully reobserve them several times within 12–72 hours to define their orbits, otherwise they are likely to be "lost." Denneau and colleagues quickly sent their discoveries to the Minor Planet Center in Cambridge, Mass., which collects and disseminates data about asteroids and comets, so that other astronomers can reobserve the objects. "Usually there are several mainland observatories that would help us confirm our discoveries, but widespread snowstorms there closed down many of them, so we had to scramble to confirm many of the discoveries ourselves," noted IfA astronomer Richard Wainscoat.
Wainscoat, astronomer David Tholen, and graduate student Marco Micheli spent the next three nights searching for the asteroids using telescopes at Mauna Kea Observatories. On Sunday night, they confirmed that two of the asteroids were near-Earth asteroids before snow on Mauna Kea forced the telescopes to close. On Monday night, they confirmed nine more before fog set in. On Tuesday night, they searched for four, but found only one. After Tuesday, the remaining unconfirmed near-Earth asteroids had moved too far to be found again. Telescopes in Arizona, Illinois, Italy, Japan, Kansas, New Mexico, and the United Kingdom, and the Faulkes Telescope on Haleakala also helped to confirm seven of the discoveries.
Two of the asteroids, it turns out, have orbits that come extremely close to Earth’s. There is no immediate danger, but a collision in the next century or so, while unlikely, cannot yet be ruled out. Astronomers will be paying close attention to these objects.
The PS1 telescope is equipped with the world’s largest digital camera (1.4 gigapixels) and an advanced data system that enables it to take pictures of a wider area of the sky than any other large telescope. The U.S. Air Force Research Laboratory funded the design and construction of PS1.