FreeLists / az-observing / [AZ-Observing] Dec 3 asteroid occultation

["Randy Peterson" <rgpeterson@xxxxxxx>]

An asteroid occultation is when an asteroid passes between us and a star, and 
the light from the star is temporarily blocked.  They typically occur in the 
wee hours with semi-dim stars, but there is a good one coming up that is early 
on a Saturday morning.  If you are interested, the rest of this email gives 
more details.  If not, please delete.

>          One of the best asteroidal occultations of 2005 will occur at
> 13:07 UT (6:07 am MST) Saturday morning,
> Dec. 3, when the very large asteroid (52) Europa will occult 8.9-mag.
> 139639 in Virgo visible from a wide path
> that includes most of southern and central California (north end of San
> Francisco Bay to Los Angeles), southern
> Nevada, Arizona, southern & central New Mexico, and western & central
> Texas. 

If you want an excellent chance to chalk-up an 
occultation event from the metro Phoenix area, this is the one to try for.  
Details at:
http://digitalmagic.i8.com/Astronomy/Occultations/051203_Europa.html
and
http://www.asteroidoccultation.com/2005_12/1203_52_3769.htm

The good: The star is magnitude 8.9.  The asteroid is large, at 
302 km.  The altitude from metro Phoenix is OK at 27 d, Az 118.  The duration 
potential is over 7 seconds, 
magnitude drop is over 3.  Time is 6:07 am MST on a Saturday morning.  We 
are well within the primary path in all of metro Phoenix.  There are two 
more 8th magnitude stars in the field of view to form a triangle to help 
identify the target star (you'll need to know how your optics flip the fov 
obviously).  
The not-so-good:  Sunrise will be progressing, but I don't 
think that will affect the event, as sunrise is 7:12 MST.  "Astronomical" 
darkness ends at 5:48, but it will still be astronomical twilight until 
6:18.

Randy Peterson
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