Monday, June 27, 2011

2011 MD - Close Approach

Today, Monday June 27 at about 17:00 UT, the asteroid designated 2011 MD will pass only 12,300 kilometers (7,600 miles) above the Earth's surface. The asteroid was discovered by Linear survey with a 1.0-m f/2.15 reflector + CCD on June 22, 2011 at magnitude 18.9.

This object is only 5-20 meters in diameter and it is in a very Earth-like orbit around the Sun. Additional observations have made it possible to exclude that this object is a piece of space junk, as was suggested early on. Calculation by Bill Gray, a well-known expert on orbital dynamics, shows that this asteroid could not have been close enough to Earth any time during the space age to have started off as a rocket booster.

Trajectory of 2011 MD from the general direction of the Sun

(credit: Nasa)

We have been able to follow-up this object few hours ago remotely from the GRAS Observatory (near Mayhill, NM) through a 0.25-m, f/3.4 reflector + CCD and from the Faulkes Telescope South through a 2.0-m f/10.0 Ritchey-Chretien + CCD.

At the moment of our images from New Mexico on June 27, 06:50UT, "2011 MD" was moving at about 132"/min and its magnitude was ~15. While the images from FTS were obtained on June 27, 09:30UT when the asteroid was moving at about 176"/min and its magnitude was ~14.5.

At the moment of its close approach later today, 2011 MD will be bright as magnitude ~11.8

Below you can see our image taken with the 0.25-m, f/3.4 reflector + CCD in New Mexico, while 2011 MD was passing nearby a bright star (click on the image for a bigger version):

Here you can see a single 20-second exposure + RGB filter image taken by 2 meters telescope at Faulkes Telescope South (click on the image for a bigger version):

While this is an animation showing the object movement in the sky. Each image was 20-second exposure with Faulkes Telescope South 2 meters telescope. Click on the thumbnail to see a bigger version:

2011 MD's Earth flyby will be a close shave, but not a record for nearby passing asteroids. The record is currently held by the asteroid 2011 CQ1, which came within 5,480 kilometers of Earth on Feb. 4 of this year. See our previous post on this object:

by Ernesto Guido, Nick Howes and Giovanni Sostero


Anonymous said...

NASA says that the minimal distant is about 18 600 km (;orb=1;cov=0;log=0;cad=1#cad) why do you say 12 000 km ? Thank you for your reply

Team said...

Near-Earth asteroid 2011 MD has passed 12,300 kilometers above the Earth's SURFACE.

If you consider that the value of the mean Earth radius is 6,371 km, you can calculate the close approach of about 18600 km from the center of our planet and NOT from the surface.


Anonymous said...

Thank you very much for your reply