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My turn on distances and durations. As said before I cut these out to
save recording time. By recording both, you thus have velocity in
degrees/second. I cannot imagine recording it in d/s in the field. Do the
two components separately and do the calculation at leisure! The
uncertainty in the final figure is going to be there no matter how you do
the initial recording.
I used the AMS durations to tenths of a second. However, it took three
full years to get it down reasonably well. The initial attempts were way
overestimated, putting every meteor at 1 or 2 full seconds! Over time my
durations shrank and were stabilized after 3 years. I tuned my sense of
short durations by watching the second hand on a watch occasionally.
Visualize a meteor during one second on the watch and at shorter intervals.
A watch with .2-sec intervals is best.
Certain intervals I never used. The ones I did were: .1, .2, .3, .5,
.7, 1.0, 1.5, 2.0, whole seconds thereafter. If the percentage difference
from one to the next got below about 30%, I could not honestly notice it.
.3 second was my most common one in the late-night hours.
Distance in degrees was no problem right from the start. Knowing
certain yardsticks like Orion's belt, Aquila's head, Dipper stars, etc.,
makes this fairly easy. But here again I did not use certain distances for
the same reason as durations. The ones I used were easy fractions of one
degree, 1,2,3,5,7,10,15, multiples of 5 thereafter.
For speeds I have generally used just 3 categories: slow, medium, fast.
Since 1982 I have classed most of my sporadics thusly. I have been doing a
fabricated-radiant project, an idea Mark Adams and I came up with to get an
empirical determination of how often sporadics line up with some radiant.
Pick a star well removed from other radiants you are monitoring and note how
many meteor path projections come within 2 degrees of the star. The speeds
will give some idea of how "fast" the "meteors" from the fab radiant are.
Path length has to be considered also: discard paths too long for so close
to the radiant and those too short for so far. You can't be exactly right
on every meteor but you should get most of them right. This project stemmed
from the problems that Povenmire was causing with his little shower that no
experienced observer was seeing anything from.
If I can see the meteor as a moving point of light, odds are I will
consider it to be slow. If only a streak of light is visible, these are
fast. Medium ones are still visible as moving points.
Practice is what gets you going, eventually. By the time you have seen
most of the major showers, your sense of speed should be fairly well
established. For major showers the projection back to the radiant is the
biggest factor: I don't get to eliminate very many good projections with
wrong speed or questionable path length.
Olivier was struck by the short length of my plots. My average length
is only about 5 degrees, but with dark skies and a good percentage of faint
ones, that makes some sense. Observing with Bill Gates, who has 3.8X my
perception, revealed a few things. He said I was seeing only a portion of
the middle of long meteors that we both saw! Even though I am looking at,
or very close to, the beginning of most of the meteors I see, I still might
be seeing only part of the path. Eyes are very poor and erratic detectors.
I am absolutely amazed that Bob has never seen a meteor longer than 5
seconds. They aren't numerous, but I have a good many of these ranging up
to 10 seconds, and my longest is 15 that was definitely not a reentry.
Longest reentry for me is 22 seconds. A few memorable long ones: 1962 green
-3 Andromedid 10 sec, 1960 blue-yellow-white -8 Taurid 8 sec, 1974 orange 0
Leonid 8 sec 140 degrees (first one of night, radiant at horizon), 1981
yellow 1 Centaurid 10 sec 120 degrees, 1973 white -8 6 sec and only 5
degrees low in SE (the one Povenmire heard). The super-long ones have a
variable speed: fastest when highest in your sky, slowest if getting low in sky.
For fireball magnitudes, I think an impression of brightened sky is
needed. Differently colored fireballs could look different in magnitude.
One thing to do on moonlit nights is to study how bright the sky around the
moon looks, then if you see a fireball that lights the sky similarly, you
have a fair idea of its brightness. I have two -12's as my brightest, one a
1979 blue Leonid with 10-minute train, the other a 1993 blue Taurid with
brief train. Povenmire has numerous -12's to -18's. He always considers my
magnitudes to be underestimated, but the opposite is true dramatically. He
sees almost every meteor 2 mags brighter than I do, a real mystery of life.
I don't feel comfortable with odd magnitudes beyond -5. There are just too
few to get any practice on.
On magnitudes in general I use whole numbers only. It would be nice to
have half-mags but most people can't avoid the bias towards whole numbers.
I feel comfortable with a whole number on 90% of the meteors I see, so any
attempt at halves would be worthless for me.
An excellent deep-sky observer, Jeff Corder, was out 2 nights last week
when I wasn't. He had 2 casual fireballs in one night: one was the
brightest he ever saw, perhaps -15 he thought, the other a -6 which he had
plenty of time to watch the train in his telescope. The brighter one could
have been a Mu Virginid; I have two fireballs from there (1983 and 1995).
I am missing a few clear May nights. Joan's car was badly damaged by a
hit-and-run, in our driveway! A speeder lost control on the curve we live
on. So I need to take her to and from work; doesn't leave enough time for
observing on week nights.
On IMO fireball forms, why is the shower not asked for?? A serious
omission. It ought to be put down, if known. Inexperienced people can't do
it, but most of us should be able to.
Late winter-early spring evenings have a slightly higher incidence of
bright meteors. I did a lot of watching at those hours in 1974 and 1975,
getting one evening bright one each week. Kappa Cygnids are a mystery to
me: I seldom see much from this one, 3/hr if I'm lucky for a single hour,
and I've never seen a fireball! Why so many are seen from Europe I don't
understand: the radiant is still 60 degrees high from here. KC's are very
distinctive in their slowness, so I'm not misclassifying them.
That's all for now. Norman