Another close encounter of a rocky kind....: 2005 YU55

Half a year after the close approach of asteroid 2011 MD (see my images here and here), another one whizzed by the Earth last night. It was 2005 YU55, a 400-meter wide asteroid discovered in 2005 by Spacewatch. It came to within 0.85 lunar distances at 23:28 UT (Nov 8, 2011), with a maximum brightness near +11.

click image to enlarge

Four hours after closest approach, I made the image above, using a "remote" 61-cm F/10 Cassegrain telescope at Sierra Stars Observatory (MPC G68). It is a 30 second exposure starting at 03:21:41 UT (9 Nov 2011), during which the asteroid (moving from right to left) has trailed considerably.

Astrometry from my images has been included in MPEC 2011-V34 (the G68 observations at

09.11922, 09.14006 and 09.32778).