2011 MD close approach

2011 MD was discovered by the LINEAR survey on Jun. 22.26 and just from its first orbital parameters it was clear that it would pass very close to the Earth five days later.
We imaged it on Jun 24- 25, 26 and 28.
Here is an animation made of five 24×10 seconds images (each stacked on the motion of the asteroid) when it was around 550.000 km from Earth and approaching, from Jun. 24.938 to 24.954, moving in constellation Hercules (less than 2 degrees from globular cluster M13) at mag. 17.8 with a speed of 11.4″/min:

On Jun. 26.06 its speed almost doubled (20.1″/min) and its distance reached 359.000 km, just inside the Moon’s orbit:

Then it reached its perigee around Jun. 27.7 at about 12.000 km from the Earth surface (transit upon South Africa and Antarctic). After 8.5 hours I was able to make some astrometry. The session lasted from 01.27 to 01.45 UT, and in this time the asteroid quickly decelerates from 168 to 162″/min, so I had to keep the exposure time at 1 second! (and of course stack many images)! In the middle of the session I expose for one minute, and the result is visible below:

Farewell 2011 MD!

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5 Responses to 2011 MD close approach

  1. manne says:

    why are you so surprised of the increase in speed .?

  2. manne says:

    speed almost doubled , in the sequence show only ?

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