[BAA-ebulletin 00985] Rare occultation of a 5th magnitude star by an asteroid visible from UK on Sept 9/10

BAA electronic bulletin

On the night of Saturday, September 9 at 23:44 UT (00:44 BST on
September 10) the asteroid (6925) Susumu (mag 17.8V) is predicted to
occult star sigma(1) Tauri (HIP 21673, mag 5.1V). A detailed account
by Alex Pratt of this very favourable event is available at:

https://www.britastro.org/node/11043

Given that the star is bright enough to be visible to the unaided eye,
and that it is a spectroscopic binary star, many observers may be
treated to a 'double' shadow cast by the star system transecting the
mid-UK region. The maximum duration of an occultation from any one
location is about 2 seconds when the star disappears from view. Be
watchful however for secondary events, either arising from the binary
nature of the star or the distinct possibility that the asteroid is a
binary system too. Although the marked uncertainty in the exact
location of the track is about 100 km, given duplicity in the
star/asteroid, observers several hundred km either side of the
centre-line should watch for a positive occultation event. Likewise,
start observing a few minutes ahead of the due time and continue a few
minutes after too in order to capture unexpected phenomena. Note that
the star is in Taurus and will be fairly low towards your eastern
horizon.

Do please make every effort, weather permitting, to observe this
especially rare event. If you are able to use a video camera hooked up
to some form of optical aid then do consider using it, as this type of
permanent record is invaluable observation-wise. Visual observers
should also attempt to time the event, both the duration of the
disappearance and the absolute time if at all possible. An easy way to
add time marks to your video record (say after the start and before
the end)is to momentarily shine a flashlight or similar near the
entrance of your optics, synchronising the flash as accurately as
possible to some reliable time signal.

Good luck everyone!

Richard Miles
Director, Asteroids and Remote Planets Section
2017 September 07 09:24 UT

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(c) 2017 British Astronomical Association http://www.britastro.org/

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Astrocomet
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Colin James Watling
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