[BAA-ebulletin 00986] Rare occultation of a 5th magnitude star by an asteroid visible from UK on Sept 9/10

[BAA electronic bulletins service]

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

P.S. Apologies if you happen to receive two copies of this message
RM