JPL (and NEODys) have removed this potential hazardous asteroid (PHA) from their risk tables due to new observations by the Spacewatch 1.8-meter telescope yesterday.
The asteroid, 2006 HZ51, is the biggest object currently on NASA-JPL's list of objects that might strike the Earth someday, with an estimated diameter of 782 meters . It is the object that has the nearest-term possible Earth-impact date of anything on the list: just over two years away, on the first day of summer (June 21) 2008. An object that big would be capable of devastating a continent, and wreaking havoc with the Earth's climate for years.
The odds of impact currently stand at just one in six million, with these odds predicted to diminish with additional observations. 2006 HZ51 was discovered on 27 April 2006, and has an estimated Mass of 6.5^11 kg.
Currently, analysis based on 13 observations spanning 1.1145 days, over the period of 2006-Apr-27.16042 to 2006-Apr-28.27491, has given the asteroid a Torino Scale (maximum) of 0. Orbital elements:
2006 HZ51 Earth MOID = 0.0608 AU Epoch 2006 Apr. 15.0 TT = JDT 2453840.5 MPC M 349.15852 (2000.0) P Q n 0.13724195 Peri. 182.13937 -0.20976829 +0.95496724 a 3.7223007 Node 75.80213 -0.89382428 -0.10029871 e 0.7111243 Incl. 12.50099 -0.39632740 -0.27924495 P 7.18 H 18.6 G 0.15