There is an opportunity to see a binocular visible star being occulted
by a large asteroid: (4) Vesta.
type of event - one involving a bright star and large asteroid - is
quite an infrequent occurrence [ see Note-1].
Something like one prediction in twenty years, where the event is potentially
visible from parts of the UK. Usually a small telescope is
needed or perhaps the unaided eye if clear and dark enough. Once the
star is located, one needs to watch for about 2 min from 2201 to 2203
Hrs. The star should disappear behind Vesta and then reappear up to
28sec later. The duration is dependent on where the observer is within
the shadow path. (Could be a short duration of a few seconds if you
are near the edge of the path).
a telescope it should also be possible to watch Vesta approach and then
occult the star. [
See further on, how-to-find the star ].
This is interesting in itself,
and one should commence observation 30min or 1 hr before, to watch Vesta
move gradually towards the occulted star.
approach or "appulse" can be seen from anywhere in the UK,
but the actual occultation is predicted for N Ireland, Isle of Man,
Northern England, Scotland and Northern Europe. The information
panel (below) show the shadow limits in yellow and a schematic
outline of Vesta in white as it crosses our line
of sight. You wont see the shape of Vesta, only the disappearance and
reappearance (D-R) of the star, which if timed accurately
(+/- 0.3sec), is a useful observation.
aware, that predictions have errors, however the certainty of this event
near the centre of the the shadow is expected to be close to 100%. (Weather
the fourth member of the "asteroid belt" to be discovered.
That was in 1807 by Heinrich Olbers. Vesta has an irregular cratered
outline. Asteroids range in size from a few meters up to about 500Km.
Vesta has a diameter of 525 Km.
It was Olbers
who proposed that a belt of material existed between Mars and Jupiter
where he suggested there were the remains of a destroyed planet. The
largest "fragments" are compared in this wiki.
One slide is reproduced here:
professional astronomers use the star occultation technique to measure
the shape of asteroids with sizes 20 km and larger.
You will need to face SW.
The occultation or close appulse is at 2202Hrs, above the horizon at
Altitude +27 and Azimuth 254 (i.e. compass bearing 254). The Moon will
have risen in the East so the sky will be brightening. It's recommended
to set up at 2100Hrs and watch the event unfold. Dress for cold conditions
and put a long dew cap on your telescope lens to stop it dewing over.
There will be detailed
maps at Steve Preston's web page
the path is updated.
Here I show some maps (1
1) Horizon view SW.
The small white square is a 10 degree area, a bit larger than low magnification
An area of sky about 7 x10 deg wide.
4-Vesta is superimposed on the occulted star plotted in orange. The
star is HIP14439 (Hipparcos
The occulted star is also know as: SAO 93276, TYC 654-1754-1, and HD19270.
If you have a goto telescope with a hand set, the SAO catalogue may
be the one to use, otherwise star-hop from a recognisable star pattern.
Watch this star.
Please send us a report if you observed or timed the D-R
name / Your astro group
What you saw / type of telescope used.
you timed the event and have UT of start / end / duration, we will send
you a report form to collect these details. Contact
firstname.lastname@example.org. or the Director
of the BAA Asteroids
and Remote Planets Section.
Note-1] There is an observing program organised
by the Intenational Occultation Timeing Association (IOTA-ES).
Observers record smaller asteroids occultaing fainter stars. These predictions
are issued monthly, and there is at least one prediction per week that
can be observed. The shadow path over Europe will involve many observers,
and the results can be remarkable. See the EURASTER.NET
More observers are welcomed. Please contact the British Astronomical
About occultations and this page:
This is a personal web page to support occultation observers. There
is a discussion group: https://groups.io/g/UKoccultations
which observers are welcome to join. An observation sent to the writer
or the BAA is a preliminary analysis prior to submission to IOTA-ES
Edwin Goffin (Hoboken, Belgium) for the prediction.
Dave Herald (Murrumbatetman, Australia) for the prediction software
SkyMap pro 11 was used to present the path on the sky and the star fields.
Steve Preston for asteroidoccultation details and updates.