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Re: PHA needs a fourth decimal point



>Another asteroid has made the Potentially Hazardous Asteroid List of  the
>MPC with a MIN. (closest approach) of 0.000 AU just like 1998 XF11 on March
>20th called 1998 FW4.  When it made the list it had a MIN. of 0.005 AU now
>it's been changed 0.000 AU.  The size of 1998FW4 is a little over 1/3 of a
>mile (approx. 600 meters). 

The 0.000 AU is a truncated value (yes the 4th decimal place is missing), but
they don't list the date for the close approach.  
According to my calculations, the asteroid made a recent close flyby of Earth on
Jan 29 at a distance of 0.201 AU.  The current orbit is calculated on only 
12 days of observations (ie: large error bars), so the orbit is still has a lot of
play in it until additional observations can nail it down.  Also, it looks
to me the 0.000+ AU encounter is sometime way into the future, at least
not within the next 100 years since 1998 FW4 is not listed in the table for 
close approaches through the end of the 21st century.

Ron Baalke