Risk monitoring 25 Dec.

One of the biggest gaps in watching for objects potentially hazardous to Earth is in the southern hemisphere, where there are far fewer telescopes and observers dedicated to the search than in the north, and no full-time sky surveys. So 2003 XB22 is an interesting case, discovered by Gordon Garradd and Rob McNaught with the 1m telescope at Siding Spring Observatory in Australia on December 15th. They picked up XB22 again yesterday and it was confirmed last night by KLENOT in the Czech Republic and announced in MPEC 2003-Y63 with a 2224 UT time stamp. JPL posted this half-kilometer object yesterday evening in Pasadena, and NEODyS listed it this morning. It isn't unusual for newly posted objects to have large numbers of impact solutions, even in the hundreds, but this object was announced with a nine-day observing arc, and both JPL and NEODyS concur in putting the first solution less than six years away, with more soon after. The good news is that JPL shows very low probabilities for all of its solutions.

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For those new to the process of detecting impact hazards, please note that, as interesting as today's "Risk monitoring" report is, there is nothing alarming here. It is all normal activity in the night-and-day cycle of observation and analysis that identifies and usually soon removes risk possibilities. An "impact solution" (also known as a "virtual impactor," or VI) is not a prediction but rather a zone of possibility that hasn't been eliminated yet. To learn more about risk monitoring, see "Understanding Risk Pages" by Jon Giorgini of JPL, and many other links related to this subject.

Further 2003 XB22 observations weren't reported in the Thursday Daily Orbit Update MPEC (DOU), but there is new data for the other four objects with impact solutions and currently in view. JPL had already updated its 2003 YD45 assessment with observations from Powell Observatory from yesterday received ahead of today's DOU, and has now updated again with a position reported from Siding Spring yesterday. The new NEODyS YD45 assessment is down to a single impact solution.

The DOU carries observations of 2003 YE45 from Powell early yesterday and from Begues Observatory this morning. Both NEODyS and JPL have updated their assessments, lowering their impact solution counts while slightly raising their overall risk ratings for this kilometer-size object.

2003 YS70 was reported from LINEAR early Tuesday, from Powell and Kingsnake observatories yesterday morning, and from KLENOT last night. Today JPL lowered its risk assessment for this tiny object.

Finally, the DOU reports observations of 2003 YT1 from Linhaceira Observarory Tuesday night, and from King Snake and Siding Spring observatories and KLENOT yesterday. Today JPL slightly lowered its risk ratings for this two-kilometer object, which goes out of view in four days.

Updated 1915 UTC:  NEODyS has now issued new risk assessments for all of its listed objects under active observation. In the last of these, it slightly raised its overall risk ratings for 2003 YS70 and 2003 YT1.

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