A LIVERPOOL ASTRONOMICAL SOCIETY PERSPECTIVE. |  |
A LIVERPOOL ASTRONOMICAL SOCIETY PERSPECTIVE. | |
This year a dozen members went to sites in Venezuela and Curacao
to observe the eclipse of February 26th. The great majority went
to a beach at Knipbaai in the far North-West of Curacao. At this
location, apart from photography, the two main experiments were
timing the duration of totality and attempting to video shadow
bands if they occurred.
Shadow bands are notoriously difficult to photograph or film. In
1976 Graham Broadbent of the LAS obtained photographs of them at
an eclipse in Zanzibar as displayed on a standard 1 metre
diameter shadow band disc. The disc follows the practice of Edgar
M.Paulton and Richard L.Feldman. The latter studied shadow bands
for over 40 years (see Sky & Telescope, Vol 39, No2 February 1970
pg 132-133). In recent years Eric Strach (or rather Mrs
M.Strach!) took on the onerous task of hauling shadow band discs
across the globe to eclipse sites usually without success. A
faint video image was recorded in 1991 but this year marked a
crowning achievement as distinct shadow bands were recorded both
before and after totality. Video frames and a report have
appeared on the LAS web site through the courtesy of LAS member Mr Gerard Gilligan who
arranged processing of the video at Liverpool University.
Unfortunately Eric Strach's vocal signals at 2nd and 3rd contacts
were drowned on his tape by shouts of excitement of the
surrounding observers. However another timing experiment was
performed by LAS member Eric Jones at a different location.
Because of this very fact of background noise, Eric Jones
accepted an invitation from Professor John Parkinson (Sheffield
Hallam University) to view the eclipse from a quiet site at the
Knip Landhuis ( a rather elegant Plantation house roughly 2km
from Knipbaai) Another possible location was next to the official
public viewing site at Watamula in the very north of the island
where under Professor Parkinson's direction a gigantic wall of
cargo containers, stacked two high, had been positioned to
protect observers from the constant trade winds which sculpt the
local low thorn bushes into fantastic shapes.
Fortunately as the morning proceeded the sky cleared and by the
time of the eclipse the sky was perfectly clear. We were
confident that the sky would be clear, as a ship (The Holland-
America Line Statendam) anchored near us just a few hundred
metres offshore. They presumably had weather satellite systems
and so the fact they had selected our location meant we were in
a good spot.
We viewed the usual pre-eclipse phenomena. The BBC filmed
crescents on the balcony floor underneath a plastic plant held
high in the air by Colin. Shortly before totality a parrot-like
bird crashed into the balcony next to Colin and the video camera.
The bird was obviously disoriented by the eclipse and so Colin
tried to soothe it. About 30 seconds before totality the cry
"shadow bands" went up and a quick glance revealed a magnificent
display of shadow bands visible not only on a small shadow band
screen next to me but also on the white-washed walls of the
villa.
In addition to the timing experiments a programme of still
photography was carried out. In fact it proceeded so well that
an extra bulb exposure was added. It is easy to lose track of
time during totality so a series of electronic alarms had been
set up as a reminder. This allowed a full 50 seconds of spare
time to look around to enjoy the near-minimum style of corona,
the nearby planets and the environment which was enlivened by the
explosions of fireworks.
Three different timing methods were used:
We also received further data from other locations. At Knipbaai
the President of the British Astronomical Association, Martin
Mobberley took a video which provided an extra timing. Also at
the same location Mr.Shelley Fey who is an experienced eclipse
observer and whose timings have been a valuable supplement to our
own data at previous eclipses provided a further measurement of
the duration of totality.
In fact we also received a video with associated GPS measurement
from yet a third location on the island of Curacao.
There was one final bonus after all the excitement of the eclipse
itself. After most people had returned home, Colin Davies and
Eric Jones lingered on in Bonaire. At approximately 9.17pm local
time on the 14th March they were treated to an occultation of
Aldebaran close to the southern limb of the Moon which was
recorded on video. This brought a very successful eclipse
expedition to a close.
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