10 Sep 2002
(Source: Sky & Telescope)
Roger W. Sinnott
Sky & Telescope
Since September 5th, the Minor Planet Mailing List (MPML) has been abuzz with speculation about an unidentified 16th- magnitude object. During the next 10 days the object will be moving rapidly across Aries and then Taurus, passing between the Pleiades and Hyades star clusters.
Bill Yeung discovered the object September 3rd in CCD images taken with an 0.45-meter telescope in Benson, Arizona. The fast-mover was "auto detected" when he analyzed his images with DC-3 Dreams' PinPoint software. Yeung e-mailed the positions to the Minor Planet Center (MPC) in Cambridge, Massachusetts ( http://cfa-www.harvard.edu/iau/mpc.html ), which quickly posted the object on its Near-Earth Object Confirmation Page under the temporary designation J002E3. But within a few days the MPC removed the object from that listing; preliminary orbit calculations suggested it was traveling in a large, 50-day orbit around the Earth, not the Sun. It had all the earmarks of being a spent rocket casing or other piece of "space junk" instead of a true minor planet.
But what exactly is it? Efforts by Tony Beresford in Australia and other satellite experts have failed to match this object with any known artificial satellite. Photometric measurements by Peter Kusnirak in the Czech Republic failed to show much variation in brightness, as would be expected of a small metallic object, especially if cylindrical. But the big question is, if it is really in Earth orbit, why has it not been detected before? In Yeung's words, 16th magnitude should have made it "a piece of cake" for survey telescopes like LINEAR and NEAT, or for CCD-equipped amateur instruments, to locate long ago.
Finally, late on September 9th, Paul Chodas (Jet Propulsion Laboratory) weighed in with this posting to the MPML:
"The unusual object J002E3, formerly on the Minor Planet Center NEO confirmation page, has been loaded into our Horizons system so that interested observers can generate ephemerides.... Further observations of the object are highly desirable to help characterize the nature of the object: we will update our orbit solution as they become available.
"Telnet and email users of Horizons can access this object by typing 'J002E3'. Web users of Horizons can access the object by going to the Major Body Menu, selecting the Spacecraft list, and choosing the entry 'J002E3 Spacecraft (UNCONFIRMED)'. The available time span is currently August 1 through December 1, 2002. The telnet address of Horizons is telnet://ssd.jpl.nasa.gov:6775/, and the web address is <<http://ssd.jpl.nasa.gov/cgi-bin/eph>>."
Amateurs who are experienced in astrometry should have no trouble recording this mystery object with CCD-equipped 8-inch and larger telescopes. Measurements should be sent both to Chodas (firstname.lastname@example.org) and to the Minor Planet Center (email@example.com) using the standard reporting format.
We don't provide an ephemeris in this AstroAlert because, like 2002 NY40 a few weeks ago, J002E3 has a very large topocentric parallax. You'll need to enter your own observatory code, or a latitude and longitude, into HORIZONS to obtain accurate predictions for your location.