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(meteorobs) Re: NWM1998 Aug 28/29 meteors dull+more
After missing nearly a week of clear nights I finally made it out 1998 Aug
28/29 for 3:11 hours. Only 26 meteors were seen the whole time, in sky
LM6.5 the first hour, improving to LM7.0 thereafter. Time observed went
from 220 to 531 EDT (620 - 931 UT). Three full hours 226 - 526 EDT had
total rates of 7,8,11 ; not much was going on. There were one South Iota
Aquarid, two North Delta Aquarids, and one Kappa Cygnid. The latter was by
far the most interesting meteor of the night ; waiting until 440 EDT to
appear, it moved sedately for 20 degrees in 4 full seconds, 0m and yellow.
I plotted about half the meteors but found no radiants. Deduct 12 seconds
for each plot.
The previous Sunday night Joan was pulling a heavy vine out of a bush in the
back yard; it broke, she fell backwards and bent her knee sideways, chipping
a small piece off the top of her left tibia. There went a planned meteor
session. We spent half of Monday visiting doctors. I have had to help her
get around all week, doing more chores and keeping ice handy. She is
gradually improving as I write with pain diminishing. It was bad timing for
the first clear week here since the beginning of June. A couple of late
nights in town were around LM6.0 so I missed some 7.3 or 7.4 skies at my
distant site.
Comments from posts of the last two weeks follow, beginning with one from Lew:
>
>>And by the way, this leads to a question of my own! Isn't there at least
the THEORETICAL possibility that one >>particular shower, the Geminids,
might drop a meteorite, since they derive from an asteroid?
In the late 60's I read about speculation on one Taurid fireball dropping a
meteorite. I'm uncertain, but think that the Prairie Network (central U.S.)
recorded this one which led to a find.
------
From Pierre (and others) concerning:
>>....Pi Eridanids. I am trying to verify their presence, which I apparently
>>observed the last couple of years. ...active between August 20 to
September 5.
>>They reach peak on August 27. The radiant
>>at max. is at 03:28 -15. Meteors from this shower are very fast with
>>velocities of 59 kilometers/second.
I have been aware of meteors coming from the big bend of Eridanus since
1961, but never enough on one night to plot and obtain a radiant. Even in
late July I see an occasional meteor coming from deep ESE, swift and almost
always trained. They continue throughout August and are most numerous late
in the month. I have not obtained any particular max date from visual
observing alone.
------
From Cathy :
>> Reminds me of a true story out in British Columbia. A guy went
>>observing, and decided to cut back across a field to his car when he was
>>done for the night. He didn't notice a steer in the field... and got gored
>>very badly in a very tender spot.<<
Some years back, in Michigan, Joan and her first husband crossed a fenced
field with some calves to reach a lake. Six months later they went there
again, but did not think about how fast the calves had grown into bulls.
Their nimble little dog distracted the approaching bulls just long enough to
make an escape.
------
From Lew again:
>>Sometime last year, Marco mentioned that he doesn't start noticing the Milky
>>Way until he gets a star count that gives an LM around 6.0 ...
>>In my case, I begin to perceive the milky way when my LM is near 5.2.
The brightest clumps in the Milky Way are visible to me around LM5.0,
particularly the heart of Sagittarius, the tail of Scorpio, and central
Cygnus. At LM6.0 all of it is visible except at low elevations. At LM7.0
it is quite prominent across most of the sky with many stars within it, the
bright clusters have some resolution into stars, and the zodiacal band is
visible. At LM7.5 it is overflowing with stars to some distance either
side, and the zodiacal band becomes quite prominent.
------
From Maj Dave Garrison, USAF Ret :
>> ... it was Sunday night so traffic was light anyway). When I reached
>>the picnic tables and looked up, I gasped, "My God".... I've NEVER EVER seen
>>the sky so clearly before, even in Colorado.
>>..dot it looked like the "Milky" part of the
>>Milky Way became resolved to my unaided eyes.
I have the same experience upon driving out to a dark site and getting my
first look for the night. Perhaps eyes are partially dark-adapted during
night driving, enough for numerous stars to be seen but not general
background sky brightness. The Milky Way is not part of the latter. The
first look usually shows a black sky, until I get further into
dark-adaptation which causes the sky to brighten up.
------
From Gary:
>>Precession generally affects all meteor streams. For instance, we now see
>>the Perseids on the night of August 11/12, but it was around August 9/10
>>when it was first studied during the 1840s.
>>
>>Gravitational perturbations can adjust a meteor stream's orbit, with those
>>with low orbital inclinations suffering the greatest effects.
This tiny effect on the Lyrids was not successfully measured until 1982. In
Meteor News number 58 ( July, 1982 ) Mark Adams used the 1922 and 1982
times of maxima to determine that "the Lyrid orbital node is advancing at a
rate of 4.7 +/- 1.3 arcseconds per year." The Lyrid max date has not
appreciably changed since antiquity since the orbit is nearly perpendicular
to the ecliptic, hence, the planets have little effect on it.. Following
are the times of two strong maxima to considerable precision giving date,
UT, solar longitude (deg), reference, observer, location:
1922 Apr 21, 19h 45m (+15m, -30m), 31.302 deg (+.010, -.021) , Olivier
(1929), H N Russell, Greece
1982 Apr 22, 06h 50m (+/- 5m), 31.381 deg (+/- .003), Adams (1982), N W
McLeod, Florida
In the latter case I personally saw 17 Lyrids in 5 minutes centered on the
peak with LM6.5, implying a maximum ZHR of 250 from latitude 26.5N. This is
much higher than the ZHR 90 being quoted for the 1982 Lyrids in IMO literature.
------
From Marco (and discussed by others):
>>eye-vision (that is perhaps why I have a quite good nighttime vision: I
>>am partly color blind). That presumably has to do with the difference in
>>number of
>>rod and pyramid receptors on the eyes reticula.
My situation is a real mixed bag. I have excellent night vision, and
excellent color perception even at low light levels. Generally I see a
half-magnitude better than most people. There have been individuals who
couldn't pass LM6.0 when I was doing LM7.3. For acuity I wear glasses
correcting me to perhaps 20/8 vision. The 20/10 line on an eye chart is the
only one that gives me any challenge, and I can read it without error. That
certainly helps me to see faint stars. When a deep-sky observer was showing
me a faint galaxy in his 17" Dobsonian, I usually would point out a couple
of fainter galaxies in the same field. But good vision for stationary
objects doesn't necessarily carry over to meteors. My perception is right
at average.
In the 1975 Florida Keys Perseid observing with six of us, four of them were
within a range of 0.8 to 1.2 times my perception for meteors, and all were
at LM7.0 or better. The last individual was Bill Gates (not from Microsoft)
with 3.8 times ! He was completely out of line with the rest of us mortals.
Bill's stationary vision was as good as mine, but for meteors he was in a
very different league.
------
From Marco again:
>>I am color contrast blind, which means that I do see colors, but not the
>>many gradations of 'normal' people...
One day looking at sunlit trees, I found out each eye responds to green
differently. My left eye sees green-yellow, but my right eye sees green-blue.
------
From George:
>> I seldom see color except for in bright meteors or in special
>>showers...such as the leonids and taurids. Most of everything else usually
>>appears simply as white to me.
Quite a few people see no color in meteors or stars. Joan gets a little
star color but meteors have to be as bright as Jupiter for her to see any
color, and it's iffy even then. I have almost 100% of my meteors at +1m
or brighter as colored (no matter how far away from central vision), about
60% of the +2m's, and 10% of the +3m's. If I am looking at the ground when
a fireball occurs, I can still give the magnitude and color just from the
flash on the ground. For a couple of years I also recorded meteor color
intensities on the following scale : 1 - subtle, like star color ; 2 -
moderate, like the strongest star or planet color; and 3 - intense, like
airplane lights. I never tallied up the results, but a rough impression is
a breakdown of 20% subtle, 40% moderate, 40% intense.
------
From George again:
>> I doubt if I observed for another 20
>>years I would acquire little more experience than I have?
Experience ought to keep accumulating over time. There is always something
to learn out there, and I have been on meteors since 1960. Building up star
knowledge never stops while waiting for meteors to appear, which is
essential for plotting skill. Knowing the charts in The Stars : A New Way
to See Them ( H A Rey) cover to cover is the way I got my jumpstart. (Any
good bookstore should have it in paperback.) I can plot a meteor in 12
seconds, and half of that is double-checking alignment in the sky with a
ruler (keeping both eyes open makes it easily visible against the sky.) My
first observing partner quit after 3 years thinking there was nothing more
to learn. Well, I have news for him : I was barely getting started when he
quit, and I know a whole lot more 35 years later. Perhaps I can excuse him,
for his interest wouldn't hold up forever with perception only half mine.
------
Looking forward to late September followed by Orionids...
Norman