If I understand correctly, the name 2003 UB313 means: 2003 - year of discovery U - 2nd half of October (A=first half of January, B=2nd half of January, C=first half of February...) B - the 2nd day in of this half-month interval. U begins on Oct. 16, so UB should be Oct. 17. 3 - The 3rd group of 25 objects discovered in the period U. 13 - The 13th object discovered in the 3rd group of 25 objects in the period U. But... The journal paper announcing the discovery says it was discovered in an image taken on October 21, 2003. Anybody know why the 4 day discrepency? Sorry for so many questions lately. I'm in my curious mood.