Near-Earth asteroid 2015 TB145

2015 TB145

This latest rock was discovered by Pan-STARRS on 2015 October 10. It is an Apollo-type object which means its orbit crosses Earth’s orbit. They reckon it is c.500 metres across and is in a short-period (3 year) highly elliptical comet-like orbit tilted 40 deg to the ecliptic.  Maybe it is a gassed-out comet nucleus. It passes us within 1.27 lunar-distances today, October 31 at 17:00 UT. The best chance to see it was last night, Friday October 30/31. I found it quite easily half an hour before midnight, in Orion at its predicted 12th magnitude, and followed it for half an hour. I got the orbital parameters from and plugged them into my Megastar software (2002 vintage). The picture is of the Megastar chart with the track of the asteroid marked, using the JPL data.  I have written on the chart what I actually saw. You can see the track is shifted slightly north and the asteroid was running a few minutes behind schedule.  I don’t know for sure why there is the small discrepancy between calculated and actual positions. I guess it is due to some parallax effect due to the asteroid’s proximity.