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(meteorobs) Re: Andromedids
Lew Gramer wrote:
>
> The Andromedids or "Bielids" were a shower known to produce incredible
> "storms" of meteors several times during the last Century. I read over
> Gary Kronk's excellent write-up of them on his Meteor Calendar at:
> http://medicine.wustldot edu/~kronkg/
>
> But I still have a couple of questions:
>
> 1) Gary mentions that the Andromedids are still observed(!), and even
> cites rates for them of up to 5 per hour in recent observations. This
> was a major surprise to me, as I've always heard they were completely
> dormant (or extinct?) over the past 50 years or so... Are there in
> fact well-documented observations of Andromedids in recent years.
>
There have been reports of the Andromedids submitted to the IMO as
recently as 1993. The rates have been much lower than 5 per hour.
> 2) What was the geocentric velocity of the Andromedids during their
> Halcyon days? Were their orbits well enough determined to give an
> exact figure for this speed?
>
The geocentric velocity for the 19th century Andromedids was 16
kilometers per second. Their orbit and their relationship to comet Biela
was well established after the 1872 display.
The velocity for the current Andromedids would be near 20 kilometers per
second from a radiant located at 01:45 +25. The date of maximum would be
near November 17th (yes, the same as the Leonids!).
This would be a good project for observers who cannot watch during the
early morning hours as the early activity period is free of moonlight
this year.
I saw one member of this shower back in the late 60's and it was the
most intensely colored orange meteor I have ever seen. It almost
bordered on being reddish.
Bob Lunsford
References: