Phocaea 


On Monday evening Oct 2 at 20:51EDT (Oct 3 at 00:51 UT),  the 75 km diameter
asteroid (25) Phocaea will occult an 8.8 mag star in the constellation Pegasus
for observers along a path from Hudson Bay, across eastern Ontario,
north-eastern New York State and southward to the Maryland-Delaware region. 
In the case of an occultation, the combined light of the asteroid and the star
will drop by 1.6 mag to 10.1 mag (the magnitude of the asteroid) for at most
6.3 seconds.  We need your help to use this opportunity to learn more about
the asteroid's size, shape and orbit.

The 94 km wide path will enter our area just east of North Bay, then run
south-south-eastward to Belleville and the Quinte Peninsula (with Kingston and
Peterborough immediately to the east and west, respectively), across Lake
Ontario, making landfall again between Rochester and New Haven, NY.  Ithaca is
right on the centreline.  From there it continues on through eastern PA,
eastern MD, DE and western NJ before heading out into the Atlantic.  

Although the rank (confidence rating) is high (99/100), there is still some
chance that the path could shift, so observers outside the path are encouraged
to participate as well.

The target star is HIP 115725.  Aka: SAO 108610.  Aka: GSC 01716 00431.  It is
about 7 degrees ne of Markab (Alpha Peg) at RA: 23 26 43.8818  DE: +19 50
26.769.  

Circumstances are pretty good for this event.  It's at a civilized hour for a
change.  The Moon will be 77% sunlit, but 53 degrees distant; the star is
quite bright and easy to find in the Great Square of Pegasus; it will be high
in the sky (>45 degrees up in the east); the delta mag is ok; and the rank is
high (99).  

IMPORTANT:  Note the difference in dates between Eastern Daylight Time (Oct 2)
and Universal Time (Oct 3).  This is one of those events that happens before
midnight local time, but is listed in all the official places on the next
calendar day in Universal Time.  This is a Monday evening event!

For more information, including finder charts, coordinates, etc, visit Steve
Preston's site at
http://www.asteroidoccultation.com/2006_10/1003_25_5550.htm.

Please see the Google map for this event on Derek Breit's website at 
http://www.poyntsource.com/New/index.htm.  Click the Google Maps button and
scroll down the Asteroid Events column to "25 Phocaea on October 3".  Read the
instructions and play around with the maps, especially the hybrid version. 
Centre your site and zoom in on it as close as you can.  Re-centre it and note
your offset from the centreline (positive if west, negative if east.  Send
your Latitude, Longitude, Altitude and offset to me at
asteroids@toronto.rasc.ca and to Derek (button at the bottom of his home page)
if you plan to observe this event.  Also check Derek's station sort (on his
home page under "North American Asteroid Events").  You might be listed there
already.

IOTA will be holding its Annual General Meeting this weekend at Mt. Cuba
Observatory near Wilmington, Delaware, which is on the centreline for the
Phocaea occultation.  No coincidence, that.  I'll attend the meeting, but then
hurry back to my observatory in northern Frontenac County (offset -28) to
observe from there.  Many other attendees plan to remain in the Wilmington
area through Monday to observe and time the occultation there.  By
coordinating our ON/NY efforts with that group and possibly others in between,
we should be able to mount a good turnout and good results -- weather
permitting, of course.   

If you are new to occultation timing and would like to know more about it,
please read "How It's Done" at http://toronto.rasc.ca/content/HowItsDone.shtml
and drop me a line at asteroids@toronto.rasc.ca .  I'll be happy to help.  But
hurry.  I'm leaving for the cottage tomorrow afternoon and will head for the
IOTA meeting from there on Friday.  This means I'll be out of Internet contact
from Wednesday ~ 3:00pm until after the event ends (unless I can get online at
Mt. Cuba).  From Wednesday evening on I can be reached by (cell) phone at
(416) 524-2618.  That phone is dedicated to the cottage, but I'll take it with
me to the meeting.