The M.A.S. Newsletter
Journal of the Mauritius Astronomical Society
October 98
Meeting:
The next meeting, weather
permitting, will be held at 6hr30 pm on Friday 31st October 1998 at the St Esprit College,
Quatre Bornes.
Open Night;
The Society is organising an
open night on Friday the 30th of this month at the St Esprit College, Quatre Bornes. All
members willing to help are kindly requested to be present. We hope to have 3 telescopes
put at the disposal of the public. These telescopes will be under the responsibility of
club members. The telescopes will be set up on the football pitch, and will be assigned to
different objects. The public will be asked to queue up to each telescope.
Occultation of Jupiter:
On the night of our meeting,
Saturday 31st, there will be an occultation of the planet Jupiter by the Moon. According
to Redshift, the start of the occultation is at 7hr13 pm and the end at 8hr37 pm.
At the ingress, Jupiter is preceeded by Callisto (at 6hr50 pm), Io (7hr07 pm) and Ganymede
(7hr10 pm), and followed by Europa (7hr17 pm). At the egress, Calisto emerges first (8hr13
pm), then Io (8hr31 pm), Ganymede (8hr35 pm), and lastly, following Jupiter, Europa (8hr41
pm). At the egress, the red spot should be visible on the central meridian of Jupiter.
Opposition of Saturn:
Saturn will be at its nearest
approach to us on the 23rd. The diameter of the ring system is then at a maximum of
45.3". A telescope of above 100mm aperture, should be able to resolve the Cassini
division under ideal seeing conditions.
The Cassini Division:
When Galileo focussed his
telescope on Saturn in the early 1600s, he noticed two puzzling lobes protruding from
opposite edges of the planet's disc. In 1655, Christian Huygens observed Saturn with a
better telescope and noted no protrusions. Having faith in Galileo's observations, Huygens
suggested that Saturn might be surrounded by a flattened ring that just happened to be
edge-on as viewed from Earth in 1655. as the quality of telescopes improved, in 1675, G.D.
Cassini discovered an apparent gap 5000km wide in the ring.
VLT v/s HST:
At the end of November, the
Hubble Deep Field South is scheduled for publication. The image will be obtained through
the use of different filters cumulating a total exposure time of 130 hours. As a
preliminary trial, at 1hr50min exposure picture has been made of a 1.3' x 1.3' field in
the constellation of the Tucan. With a time exposure of 1hr15min, the VLT achieved a
better image.
Serge Florens, Secretary