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Re: Scintillation



Lew,

I live in S. Calif. about 20 miles North of the mexican border...East of San
Diego.  I observe in the local mountains about 35 miles East of San diego.
 Usually above the fog pattern and with fairly dark skies...unless you look
directly west.  I usually observe facing north, south, or East and any
combinations of those three directions.  Actually, I have a very good
location. I usually get an LM on dark nites near 6.0...but that's a function
of my eyesight.  Bob frequently observes with me and usually has an LM in the
neighborhood of 6.5 to about 6.8...sometimes better.  About IMO and NAMN not
providing a format to Report Seeing Conditions.  If it's in reference to moon
effects, this kind of info is automatically determined by the date when
entered into the computer.  It knows when the moon rises and where it's at
etc.  Also it knows where it is at in relation to where you are viewing...via
your center of view (RA and Dec) entry.  As to other seeing conditions, that
becomes obvious with your star count for LM's...especially if you make counts
from more than one star count area. 

In reference to Scintillations.  Well, to tell the truth, I don't think I
ever seen any scintillations in the center of my view from anything other
than very very dim stars. On occasions I may see something near the center
that may momentary fool me, but these are usually from watery eyes or
something of that nature. To tell the difference between a scintillated star
and a dim meteor should be no problem either.  If the scintillation appears
stationary..dot it's probably a star.  If it moves, you have a meteor candidate.
If you are able to see a very dim star because of scintillation, I doubt
there's enough photons to sustain a meteorlike streak. Now I do see the
twinkling of stars which is atmosphere caused and I seldom make a mistake
here due to lack of linear movement. Sometimes the head will turn and out of
the periphory(Sp) of my vision I may note a streak, but this is usually
easily discounted because there is an air of doubt coupled with usually a
fairly bright star in the very same vicinity of the suspected motion. Again,
if in doubt, don't count it. Keep to this pattern and you will be okay in the
long run.  You will probably miss a few meteors, but most likely you will not
be counting a lot more eroneous sightings. 

As to about when to begin observations for any given radiant.  Well,
personally this is no problem for me. Work or no work the next day...if the
moon is out of the way or not too bright,  I begin my observations near 10 pm
local. The exceptions are for various major showers that has the radiant up
earlier...such as the Perseids, Geminids and Ursids.  But I observe on any
night that I'm able...particularly if the sky is dark and clear. I'll give a
meteor shower consideration if it occurred within an hour before the radiant
actually rises. Then these meteors have to be following a path that would
bring it back to  within about 10 degrees of the radiant.  If you know the
sky well enough, this is not too difficult of a task.  But any meteor from a
radiant that is within an hour  below the horizon or pretty much at the
radiant, will display some distinguishing characteristics.  Namely, they will
be very long.  If its a short meteor properly aligned with a radiant, I won't
consider it as a shower member.  I don't and I doubt IMO gives any serious
consideration to any of my results at the early risings of a radiant.  This
kind of data may be more valuable in seeing how a shower progresses or viewed
to progress...perhaps someday used to refined various ZHR formulas. To refine
ZHR formulas to much above "ballpark" figures, Perception coefficients need
to be figured and  Very few people has had  their individual perception
coefficients figured out.  This is a quite involved process...namely
segregating one's sporadics from various showers that are active during the
month of August for the Northern Hemisphere observers and I believe it's
during the month of February for the Southern Hemisphere observers?  Anyhow,
I'm not too sharp on that, but I know Peter Jenniskens is up to snuff on that
area.

George