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(meteorobs) Come back alpha-Lyrids, all is forgotten
There is one notable omission from Mark's NAMN notes for July---the
alpha Lyrids---probably because it is mainly a telescopic shower.
It is something of an enigma. At its discovery in 1958 and in the
sixties this was easily the most profilic telescopic shower of the
year---some two to three times the best telescopic showers of today.
On a visual scale it would have been the equivalent of a ZHR around
150. The alpha-Lyrids are fast moving and come from a 2-degree
diameter radiant.
Strong activity was again recorded in 1969 and 1971. The shower was
seen a decade later, but it was not so prolific. That apparent
decline continued in 1989 and 1990 when IMO observers in Malta and
Belgium barely detected it. It produced at a tenth of the sporadic
background, the equivalent of a poor minor shower. In the intervening
thirty years the radiant appeared to have moved north some six degrees
to RA=281d, Dec=+44.5d. Since then few observations have been made.
Is this a permanent decline or its there some as yet undiscovered
periodicity? Will the shower return to its former glories? The only
way to tell is to keep watching. The activity period is approximately
July 12--20. At the same time it is possible to record
omicron-Draconid minor shower radiating from 276d, +62d.
Those with IMO charts are recommended to use 47, 69, and 70 for both
showers. These are centred at 18h48m, +56d; 17h40m, +48d; and 19h50m,
+46d respectively. Uranometria charts are suitable for observations
for binocular up to 50mm aperture. At present I don't have chart
making facilities, but I do have an archive of charts on paper. I'm
working on rewriting my code to work with a graphics package which
will generate GIF files so that charts will be accessible from the
Web.
An outline of the observing method is in
http://Web.InfoAvedot net/~meteorobs/guidechap4.html
and you can obtain further details from me directly.
For historical details of the alpha-Lyrids, see Gary Kronk's
description at
http://comets.amsmeteors.org/meteors/showers/alpha_lyrids.html
Malcolm Currie
tele@imodot net
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