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(meteorobs) Re: sky measuring sticks+reentry+more
The recent thread on measuring angles in the sky brought up some rather
involved mechanical methods of doing the measuring. I have used the
following natural measuring sticks throughout my life, in degrees :
Pollux - Castor 5
head of Aquila 5
belt of Orion 3
Deneb - Albireo 23
open bowl of Big Dipper 10
pointers of Big Dipper 5
Mizar - Alcaid 7
W of Cassiopeia width 14
altitude of Polaris for my location - variable
That's it. Once these are known, you don't need to rely on body parts.
Southern hemisphere observers will need something additional that they can
see from there. The short distances are far more important for meteors,
and I saw little discussion on these. Once you reach 20-degree meteor path
lengths, a length to the nearest 5 degrees is sufficient. I frankly can't
tell the difference between 39 and 40 degrees, for example, anyway.
The public is unable to judge any kind of angle. They understand "horizon"
all right. The term "overhead" sounds like a precise term but it is
actually vague. An uninformed person might say a bright meteor "passed
overhead" if it was as low as 65 degrees ! Just because your neck hurts
when you look up doesn't mean you are looking at the zenith. Try deciding
where the zenith is just by looking up. Then get a star chart with
declinations on it and find out where your zenith really is. I could be off
by 10 degrees going by feel alone.
Any elevation between "horizon" and "overhead" the public tends to call
"45 degrees." That is the best-known non-right-angle angle. Be suspicious
any time someone reports seeing something at elevation 45. That happened to
me in one astronomy class ; a student saw a fireball in the north 45 degrees
up. I went over to his place and had him point out where he saw it --
turned out it was only 15 degrees up ! It was below Polaris, which was 27
degrees. That's quite an oversight when I had discussed this in class.
To plot meteors it is essential to know stars down to at least 4th
magnitude. There aren't enough brighter stars to work with and get any
semblance of accurate plots. Learning the constellations should be done
first. I used the Rey book, The Stars : A New Way to See Them, the best
available, and had a good working knowledge of the sky in just four months.
A year of just recording some meteor data along with learning constellations
ought to be done before trying plots. Few plots occur right between two
stars. Most often I have to use a couple of stars that the meteor missed by
a degree or two to anchor the path. I use a ruler against the sky.
There was another reentry last week which Chip in Pensacola definitely saw.
It also passed over the Tampa-St. Petersburg area and caused yet another
ruckus on the Art Bell show with Peter Davenport. We lost a pastor in Tampa
to the UFO side because he saw this one, and for the first time he didn't
know what he was seeing. The radio principals lament the refusal of
scientists to return telephone calls and wonder why. They conjecture that
scientists don't know what it was either, that secrets are being withheld
from the public, and that we are being lied to. I can help them out : calls
aren't returned because Mr. Davenport won't believe scientists anyway hence
they know not to waste their time with him. I found that out for myself two
years ago with the Seattle reentry ; nothing I said was accepted. We can
reach people numbered in the hundreds with rational scientific discussion,
but Art Bell reaches millions with grossly and willfully ignorant
discussion, outnumbering us by 10000 to 1. I still haven't seen one of
these spectacular reentries and this latest one missed me by only a hundred
miles, plus it was mostly cloudy here.
On Aug 19 GWG wrote :
> In Norman's case, his glasses may allow him to see 7th
>magnitude stars, but restrict his field of view; thus making the
[perception] correction
>inaccurate for him. For most others, the correction probably works just fine.
My glasses have a field of view 140 degrees wide and 110 degrees vertical.
I see so few meteors near or beyond the frames that I don't consider them to
be any restriction. I have always gone after the largest lenses possible.
That was a bit hard in the late 60's when small lenses became fashionable,
some little more than slits. Then big lenses returned by the early 70's,
and since then plenty of very big ones have been available.
On July 11 Kim wrote :
>Meteors 14 and 13 were, for all practical purposes,
>simultaneous, with 14 occuring immediatly after the
>appearance of 13.
A strict definition of "simultaneous" needs to be observed, that is, both
meteors had to be visible together for any noticeable portion of their
appearances. If any break between them occurs, or if one starts just as the
other ends, then they are not simultaneous. I have noted all occurrences of
simultaneous meteors from my beginning. Probably the easiest way to see two
at once is to have a slow one in progress, then have a fast one flash into
view. Many times I have noted a beginner or casual Perseid observer saying
"several were visible at once," when he meant to say "several were visible
in quick succession." There have been only six times in 39 years when I saw
three simultaneous meteors, and I have never seen four.
In Chris Crawford's group setup, will meteor data be recorded? I hope
individual rates will be produced rather than an attempt to find how many
unique meteors appeared. The latter can't be used for comparison with
individuals.
We got by without any problem from Floyd. Tomorrow night I would expect to
be clear. What sky I could see yesterday was free of haze.
Norman
Norman W. McLeod III
Asst Visual Program Coordinator
American Meteor Society
Fort Myers, Florida
nmcleod@peganet.com
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