This is about a stellar rather than a solar eclipse, but I
believe that some on this list live in or near the path that
extends from southern California to Alberta, and may be
interested in this event, quite rare for a star this
bright
though not as spectacular as a solar eclipse.
For the general public, I call it by the better-known
term eclipse
rather than occultation.
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The occultation of Zeta Ophiuchi
by (824) Anastasia on Monday
night/early Tuesday morning, April 5/6, is the brightest asteroidal
occultation ever
predicted for North America involving an asteroid
this large. This is a naked-eye event that could be seen by many
thousands in and near the predicted path. The International
Occultation Timing Asssociation (IOTA) encourages
as many as
possible to try to see and time this occultation, to obtain as
detailed an outline of the asteroid as
possible, to accurately
measure its size and shape. Not just amateur astronomers, but anyone
with the most rudimentary
knowledge of the sky, can find the 2.5-
mag. star with simple full-sky charts that I've prepared and that
Brad Timerson
has placed on a Web page about this event at
http://www.asteroidoccultation.com/observations/NA/Anastasia/ .
Also on that Web site is information about how the occultation can
be timed with simple techniques, ranging from
just watching and
counting to video recording the event with camcorders.
Those
in the region of possible visibility, extending from
southern California to Alberta, are encouraged to pass this
information
on to their friends, and especially to distribute it on
astronomical society list servers so that nearly everyone in
organized astronomy clubs throughout the region can learn of this
rare event. Hopefully, information about this
will be distributed
by local media, at least in the form of short messages, like the
first paragraph above pointing
to the Web site where detailed
information is available. For general consumption, I've used the
more familiar
"eclipse" rather than "occultation" in most places on
the Web site, but do explain that "occultation"
is the astronomical
term used for the phenomenon.
I give parts of the information
on the Web site below; you are
encouraged to visit it yourself to learn details of the event and
how it might be
observed. The full-sky charts were produced on the
http://www.heavens-above.com Web site and edited to emphasize the
information needed for this event. At the end of this message, I
give
a short paragraph that you might use to send to your friends
and even local media, to encourage others to visit the Web
site and
try to observe this unique event.
_________________
Some of the information from the Web site:
The eclipse of the star Zeta Ophiuchi will last up to 8 seconds in a
25-mile-wide path from the Los Angeles area
to Edmonton, Alberta
ANYONE in the path can help accurately measure the size and shape of
the asteroid by
making simple observations of the eclipse
The International Occultation Timing Association (IOTA) seeks as
many
observations of the eclipse as possible
Seeing a star suddenly vanish, then abruptly reappear several
seconds
later when a faint asteroid passes in front of it, is a
startling sight that will always be remembered. Millions
of people
will have a chance to see such an event before sunrise early Tuesday
morning, April 6th.
Anyone
who can see and count, lives in or near the eclipse path, and
is willing to get up in the middle of the night and go
outside for
about ten minutes, can help us measure the size and shape of the
asteroid 824 Anastasia, if the sky
is clear. We want as many as
possible to try to observe the eclipse since the detail of
Anastasia's shape
that we can derive is proportional to the number
of places from which the eclipse is observed. Opportunities to
see
eclipses of bright naked-eye stars by asteroids are rare; this is
the brightest star to be eclipsed by an asteroid
of this size or
larger that has ever been predicted for North America. During a
similar event in China in
1991, 3000 tried to see the eclipse, but
only 4 of them actually saw it, since the predictions then could
only predict
the eclipse path's location to about 30 path-widths,
and the actual path was a little farther from the predicted one
than
expected. Since then, thanks primarily to the European Space
Agency's star-position-measuring spacecraft
HIPPARCOS, our
predictions have greatly improved; for the Anastasia eclipse, we
expect the error to be about 5 path-widths.
You don't have to be an amateur astronomer to contribute; the charts
on this Web site will allow anyone with
only a rudimentary knowledge
of the sky to find the star, Zeta Ophiuchi. It is bright enough to
see with the
naked eye; you don't even need binoculars, although if
steadily held, such as against a fence post, they would give a
better view. The star is bright enough to record with many
camcorders, especially those with "night" modes.
Very accurate
observations can be made with such camcorders so if you have one,
you are encouraged to use it to
record the eclipse. Time accurate
enough for this event can be obtained from
http://www.time.gov .
Basically, try to time the eclipse with whatever resources you have,
even if that's just your eyes and ability
to count.
Results from observations that we receive will be posted on IOTA's
asteroidal occultation results
Web site at
http://www.asteroidoccultation.com/observations/Results/index.html .
A good example of results of another occultation, of the star HIP
13021 by the asteroid 135 Hertha that was observed
on December 11,
2008, by observers in the path from Oklahoma to southern California,
are shown at
http://www.asteroidoccultation.com/observations/Results/Data2008/HerthaProfileNEWcolor.jpg .
The figure projects the observed occultation timings onto the plane
of the sky at the asteroid, thus revealing
the dimensions and
peanut-shape of 135 Hertha. Small telescopes were needed to see HIP
13021 since it was
about 200 times fainter than Zeta Ophiuchi.
We look forward to adding your observation to the outline of
Anastasia
that we hope to obtain following the April 6th eclipse.
_____________________________
A short version suitable
for non-astronomers and the media; in the
first sentence, you might replace "a path extending from the Los
Angeles
area to Edmonton, Alberta" with "our area":
Late Monday night/early
Tuesday morning, April 5/6, anyone in
a path extending from the Los Angeles area to Edmonton, Alberta has
a chance
to see a naked-eye star suddenly vanish, then abruptly
reappear several seconds later as the asteroid 824 Anastasia passes
in front of it. The International Occultation Timing Association
(IOTA) wants as many as possible to watch this
eclipse, timing its
length simply by counting, or perhaps video recording it with a
camcorder. Anyone with
the most rudimentary knowledge of the sky,
not just amateur astronomers, can help with this project to map the
outline
of Anastasia; the detail of the shape that we can measure is
proportional to the number of locations from which it can
be
observed. Descriptions and simple full-sky charts, on a Web page
about this event at
http://www.asteroidoccultation.com/observations/NA/Anastasia/ ,
show how, starting from the rising last quarter Moon, you can easily
locate Zeta Ophiuchi, the star that will
be eclipsed.
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