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re: (meteorobs) Time of Geminid maximum
Wayne wrote:
> Don't forget, Gary's book was not written for a specific year...due to the
> calendar induced drift of date vs Solar Long (leap year and the extra 1/4
> day each year) any thing there would be implied to have a +/- half day
> jitter. I do not recall him giving times that precisely.
> I'll check Gary's page. Any idea who the 0700 source was?
Yes I'm aware of that. The guy quoted a time. All I could find was a
solar longitude (which I interpreted at B1950). I've asked him where
he found a time for 1996 in Gary's pages, and what his other source
was.
> My final point would be...especially with major showers is that these
> are predicted times. What we need is a group of dedicated observers on
> either side of it to watch and report their data to further refine this
> time :-> THat's why we're here.
Absolutely. I've told the chap the same thing. The maximum is broad,
the time of maximum is uncertain by +/-3 hours say, and looking at the
IMO Visual Handbook appears to extend from about 261.9 to 262.4, with
possibly a plateau around 261.9 to 262.2, and a main peak around
261.3. (It may even be a double peak, though this is highly
speculative based on the data presented in the Handbook.) So I said
he'll see good activity on all the nights from Dec. 12 to 14, and
encouraged him to look on other nights too. We need better statistics
on the changing average brightness through the shower, for instance.
My post on meteorobs was really to highlight such discrepancies in
general, and to ponder what if anything we should do about it. So
many publications just duplicate some old text book without allowing
for modern global data, orbit evolution, and new showers. For them
meteor showers are static, unchanging from year to year (wouldn't that
be boring), when we know that the skies are ever changing, and ever
fascinating because of the unpredictability. There is one olde table
of the major showers which includes the Andromedids and appears in so
many general astronomy texts written by non-meteor people I cringe
every time I see it. I spotted in again in a new book only last week.
There's another Patrick Moore used a lot based upon an old BAA
Handbook. So should we be writing to the publishers/authors?
Malcolm
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