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(meteorobs) Locating Constellations
Over time there have been various request by novice amateur astronomers
for assistance in locating constellations. The replies have been very
good because they were given by people who had shared in these
difficulties. However one aid that was never mentioned which is useful
to the novice as well as an old hand. That device goes by various
names; Planet and star locator, Planisphere, Astro Disk, Star and
planet finder, etc. It consists of a plastic or cardboard disk
constellation star map of the whole sky sandwiched between two layers
with windows that open to the visible night sky at any given time. This
star disk is indexed on its periphery so that it may be rotated to
current date and time of the night to display just the visible sky for
that moment in time. They come in various sizes from about 5" to 11".
I would suggest you buy the largest size available. The Sky Publishing
Company offers a good variety of choices( www.skypub.com ). These
devices are useful not only in showing you what constellations are
visible and they indicate objects of interest but they also serve as
sort of a circular slide rule to calculate painlessly positions that
would involve a lot of calculation relating UT, Sidereal Time and Local
time. For example given the coordinates of the radiant of a meteor
shower, simply rotate the disk till the radiant is on the meridian and
(Oh-Lah!) read the times and dates off of the rim of the wheel when this
condition will occur. Absolutely painless 8-).
Clear skies and good seeing. Robert
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