View Full Version : Occultation of the asteroid 4 Vesta

2012-Jan-02, 09:19 PM
On January 3th will be a rare occultation of the asteroid 4 Vesta by another asteroid for 34 seconds.


2012-Jan-03, 08:49 PM
Hi Ricci,
It was daytime here (San Francisco), so I didn't get a chance to look. Too bad since Vesta is easy to spot in binoculars.

When I run the numbers, I get a near miss rather than an occultation, although it's possible I did something wrong.

On Jan 3, 19:42:23, Vesta will be 424,281,716 km from Earth. With a diameter of about 500 km, it's disk will be about atn(diameter/distance) = 0.25 arcsecond. I'm guessing 2000 AK9 is much smaller.

According to JPL Horizons, at that moment, relative to Geocenter, the position vectors of each object is:
Vesta: 3.854671178722219E+08 -1.722267865563862E+08 -4.204771236532170E+07
2000 AK9: 3.540817447354714E+08 -1.582029088830698E+08 -3.862151229035653E+07

This gives them an angular distance of
acos(Vesta dot AK / (|Vesta| |AK|) = 1.4 arcseconds

Trying various locations on Earth's surface fails to get AK9 within an arcsecond of Vesta. Northern latitudes come the closest.