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re: (meteorobs) Time of Geminid maximum
Malcolm,
I go through this exercise with each major shower when planning my
(and advising the NJAA meteor observers) For the Gemininds, the IMO
published peak is 1600 UT, DMS it is 1830 UT.
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.
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.
In this specific case, all times are during the day for US and
twilight for Europe, so we should be observing the day before and after
anyway. I would think that the IMO and DMS times are pretty much
equivilent. I'll check Gary's page. Any idea who the 0700 source was?
Wayne
-------------
Original Text
From: Malcolm Currie <mjc@astro1.bnsc.rl.acdot uk>, on 12/3/96 9:51 PM:
To: <meteorobs@latradedot com>
A UK observer sent me an e-mail today. The gist of his message
was that he was trying to locate the time of maximum for the Geminids
and found widely differing values. He wrote:
"It's given as 16h UT 13/Dec on the IMO pages. Gary Kronk's page gives
0030 UT. Another source gives 0700."
I couldn't locate the 0030 reference in Gary's Meteor Shower pages,
only lambda_sol=261.3 (presumably B1950). It must be disconcerting to
find such diverse times.
Any comments why there might be such a wide discrepancy? I wondered
if someone was using the wrong equinox, or were using the solar
longitude from a generation ago. My WGN and BAA Journals are at home,
so I can't research this now. The lambda_sol=262.0 (J2000) certainly
sounds right. I see the DMS page reckons 0.1d later, which looks to
be the same as the IMO time within the uncertainties.
Malcolm
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