The Asteroid/Comet Connection's
daily news journal about
asteroids, comets, and meteors

Today's issue status: done

• News briefs – distant occultations & meteor news

Cover: Rosetta destination, 67P/Churyumov-Gerasimenko [link|alt] imaged February 26th by Olivier Hainaut and Mauricio Martinez with the ESO 3.5m New Technology Telescope (NTT) at La Silla, Chile with SuSI-2 camera with a 45-min. B-filter exposure and 35-min. exposures each with V and R filters, shown both stacked on the comet (stars streaked) and on the stars (inset, comet as streak). The images, ©Copyright ESO, are shown with north up and east left, unlike the PR originals. ESO's caption notes that, "The fact that the image of the comet's 'dirty snowball' nucleus is almost star-like indicates that it is surrounded by a very small amount of gas or dust."

Distant occultations:  While preparing the Saturday occultation cover and news item, David Dunham's event list was noticed to include comet/Centaur Chiron and two Edgeworth-Kuiper Belt objects (EKBOs, aka TNOs). Mike Kretlow's 2004 predictions also include "Centaurs and TNOs." This is cutting-edge science with little precedent. EKBO occultation observation could reveal not just size but also companion objects, a coma, or, for the largest objects, even an atmosphere (Pluto's atmosphere is only known this way).

Occultations should reveal EKBOs smaller than can be seen by reflected sunlight with today's telescopes, and the Taiwan-America Occultation Survey (TAOS) is preparing to study the EKBO population by sampling unpredicted occultations. Capable of catching events lasting only 0.2 second, it will rule out error by cross-checking results from four 0.5m telescopes in pairs at two locations tracking the same patch of sky. They will use a novel shutterless CCD "zipper mode" that trades one physical dimension for time. Their 2048x2048 CCDs produce 2048x64 fields, with

the second 2048-pixel dimension shifted into 64 pixels of CCD memory. The pictures aren't pretty, but the point is to simultaneously and continuously watch many stars to catch one blinking out for a fraction of a second. A TAOS news item of February 23rd shows a successful practice run with a predicted occultation by Main Belt asteroid 51 Nemausa two days earlier.

For more info, see a 770Kb PDF project overview by Chyng-Lan Liang et al. at UCB Statistics.

Meteor news:  An article at PhysicsWeb today, telling about magnetized carbon nanotubes, explains that the question of whether carbon has an intrinsic magnetic property was answered by a meteorite:

“ In 2002 [Michael] Coey's group measured the magnetic properties of a meteorite sample and found that only two-thirds of the magnetization could be accounted for by magnetic minerals present in the sample. The rest, they argued, must come from the carbon. ”

A 13 November 2002 PhysicsWeb article tells more about that research involving a Diablo Canyon meteorite sample from the small iron-nickel asteroid that created Arizona's Barringer Crater about 50,000 years ago.