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(meteorobs) Draconids in 1993, 1994
Hello Lew and everyone,
Lew Gramer wrote:
>Alas, the elusive Draconids are what is known as a "periodic" (as
>opposed to an "annual") shower: they seem to only appear in years
>when their parent body, Comet Giacobini-Zinner is near perihelion!
>(Although I did just hear this year that some observing groups do
>report very low ZHRs for this shower in occasional off years...)
Yes, I believe Draconids are sometimes active in an "off" year.
During most years, I would not expect any significant outburst,
but some very weak activity can still be seen as was the case
in 1993 and 1994. I would be VERY interested to know if anyone
else had success detecting activity in those years.
1993, October 9/10
Shortly after midnight, I checked the sky for weather conditions
throught a window facing north. By pure chance, within one minute,
a very slow approx magnitude -1, descended toward horizon. It lasted
a few seconds with wake. Path lenght/alignment matched with GIA
radiant. Went outside to observe 30 min. starting at 12:30 edt.
No further GIA were seen.
1994, October 7/8
Early evening, first dark hour after sunset. Casually watched the
sky in my backyard as I was preparing to observe more seriously later
on. In only 20 minutes, 2 slow and faint but trained meteors aligned
with GIA. One of these was very short and came right out of the
radiant!. 2 other meteors also aligned but were medium speed.
Regrettably, I went back in and naped until midnight. I thought
the rates would increase in the morning hours! I began visual
recording at midnight local, observed 3 hours with no GIA. Skies
gradually clouded over for the last 2 hours. Only a handful of
sporadics were seen.
>Which brings up an interesting question: how many other periodic
>meteor showers are there? In other words, showers which are not
>even perceptible as *minor* showers in their off years, but yet
>which are still known or predicted to return in the years ahead?
My guess or theory is - very few or none. I think the periodic
showers are NOT really periodic at all. In most years, the rates of
these showers are VERY weak and too difficult or impossible to identify
among the sporadic background. But in some "off" years, the very weak
rates could spurt without warning and become briefly detectable.
>The Bielids/Andromedids are long dead (we believe). The Alpha
>Monocerotids, Pi Puppids, and other "outburst showers" ARE still
>perceptible in off years, albeit they are very minor then. But
>what showers other than the GIAs do we know of that are neither
>"extinct" NOR annual?
I may be wrong, but I have always thought of the GIAs as a truly
unique shower, standing out from all the rest for its wildly
variable activity. This has fascinated me for years and prompted
me to learn more about it and to watch for them every year
regardless of predictions. So, I dont think the Draconids are
periodic, just highly variable (VERY weak to storm rates).
Perhaps, the reason why zero activity is seen almost every "off"
year is because the (weak!) activity is so short in duration,
it is usually missed! Even this year's high GIA rates were seen
by a small number of very lucky observers. One needs to be at the
right place, right time.
>Clear skies!
>Lew
Its variable skies on Oct 9/10 near Ottawa, Ontario. Not a good night
to observe I'm afraid. But if it clears enough, I'll quickly set up in
my backyard. Weather should improve for Oct 10/11. Good luck and
remember that LATE Draconid activity could still be possible!
. . . .
Pierre Martin . . * . * . .
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Ottawa, Ontario, CAN . . . . .
home: p.martin@cyberusdot ca / . . . .
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