2005 YU55
by Pete Peterson
Tuesday, 8 Nov 2011 The sky’s clear for the close flyby of asteroid 2005 YU55. I’m out by 17:30 turning the observatory on and preparing to take a new set of flats. But the camera driver has been corrupted and although I eventually get it operating I’m running behind schedule all evening.
Around 18:35 I did locate this potentially hazardous Apollo. With 6 second exposures it was a bright short streak as it moved from image center to image edge before I could even start saving the images. The asteroid was running about 2 minutes ahead of predicted schedule, and eventually I did capture astrometric quality images:
28 X 1 second exposures, binned 2X2, cooled -20C, unguided. No darks or flats were applied but the image was Photoshopped in an attempt to enhance the view of the asteroid as it traveled from the middle of the right hand (west) edge to the upper part of the left hand (east) edge.
C2005 YU55 is passing approximately 200,000 miles above Earth at 18:28 hrs. I started imaging at 18:56 and the frames used were taken from approximately 18:57:53 – 18:19 hrs. Movement is approximately 8°/hr. Frames 13, 25 & 38 were used for astrometry. Although the position was accurately determined it was too far from predicted for the computer to provide a variation value. Magnitude measured at 12.4.
This is it for the night. The astrometry was performed immediately and the dome was shut down by 19:19 hrs.
The data was immediately emailed to the MPC, and I received an unheard of email back within minutes. Apparently they were staffed and awaiting data. Unfortunately, the message wasn’t good news: “Your observations of K05Y55U are not hanging together with an orbit including the latest radar observations.”
My setup was triple checked, as was the astrometry. There were 140 calibration stars in the images used and the time was good to ½ second. Interestingly today, 24 hours later, no observations have yet to be posted by the MPC.
Pete Peterson
