Asteroid 2005 JB22


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...the planet that the little prince came from was scarcely any larger than a house.
-- Antoine de Saint-Exupery

(L) Part of the Spacewatch image on which asteroid 2005 JB22 was
discovered; the asteroid is the diagonal streak near the center.
(R) The triplet of images showing the asteroid. (Spacewatch /Lunar
and Planetary Laboratory / University of Arizona. James V. Scotti,
Observer. Copyright (c) 2005 Arizona Board of Regents.)




On May 7, 2005, I found the near-Earth asteroid that has since been designated 2005 JB22 as a volunteer reviewer for the Spacewatch FMO Project. Before making this find, I had searched approximately 1,565 Spacewatch images since the previous September. Over that period, I had submitted more than 1,300 FMO candidates and resubmitted about 80 of the most promising ones, with no luck. On this particular image, though, I noticed a diffuse streak reminiscent of FMOs I'd seen on the project site, so I submitted it. When I received the triplet of images back from Spacewatch, it still looked promising, so I resubmitted it. The next morning, I received an e-mail from Spacewatch, telling me it was a real FMO, and it had been posted on the Near-Earth Object Confirmation Page (NEOCP). Spacewatch had only been able to get three positions for the asteroid, so I anxiously awaited for the NEOCP to be updated. (About a quarter of the asteroids found by the FMO Project have proven unconfirmable due to faintness and/or fast motion.) That evening, the page was updated as confirmations were received, including one from Peter Birtwhistle of Great Shefford Observatory. Great Shefford Observatory in the UK, whom I'd met last year at the International Workshop on Cometary Astronomy. Peter's composite image of the asteroid appears below. The discovery notice was released the next day; it showed that the asteroid was also confirmed by the Catalina Sky Survey and the Grassland Observatory in Arizona, Table Mountain Observatory in California, and Calar Alto Observatory in Spain.

Image of 2005 JB22 (when still known by its provisional
designation, SW40MS) from May 8, 2005 by Peter Birtwhistle,
Great Shefford Observatory, a composite of 71 30-second
exposures guided at sidereal rate taken through a 0.3-meter
SCT with Apogee AP47p CCD camera, offset in Astrometrica
by the asteroid's predicted motion so that the stars appear as
trails while the asteroid's image is built up.


The orbital period of 2005 JB22 is 400 days; Its perihelion distance is 0.678 AU, less than the distance from Venus to the Sun, and aphelion at 1.45 AU, out at the orbit of Mars—though because of the asteroid’s inclination (nearly 16 degrees to the ecliptic plane) and alignment, it doesn’t come close to either of those planets. Close approaches to Earth can occur around April 30 and October 17, with the April approaches the closer. A week before discovery, 2005 JB22 passed 0.03 AU, or 2.8 million miles (about 12 times the Earth-Moon distance) from Earth. The asteroid is estimated to be between 30 and 70 meters in diameter; the exact size depends on the asteroid’s albedo (reflectivity), which is determined by its composition. If it's an S-type asteroid (a combination of rock and metal, mostly nickel-iron with silicates of iron and magnesium), it would be more reflective and smaller, while a C-type (carbonaceous, related to carbonaceous chondrite meteorites) asteroid would be darker yet larger than an S-type. We have no way of knowing, though, to which class 2005 JB22 belongs.


Asteroid 2005 JB22

The orbit of 2005 JB22, with its position and those of the planets shown
as they appeared at discovery on May 7, 2005.



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