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(meteorobs) Plotting: 3 Stooges Method
Kim Y wrote:
As part of my continuing education in meteor observation, I
have slowly been working my way into plotting. I must admit, never have
I found anything that seemed so deceptively simple to be so
confoundingly frustrating. A typical attempt at plotting a single
meteor may go something like this:
<snipped humerous, but all too real account of plotting for the
beginner, except for:>
"5:40 UT, a meteor appears that *may* be coming from a known
radiant. I decide to plot it. I throw my ruler up into the air to
"place" the path."
WTH>> I prefer the string method, since it's easier for me, but the ruler
is OK
5:40:30, I feel I have the path, now I need to see the time. I
grope for my recorder, finally find the pause button, while still
holding the ruler to the sky. I look down at the watch glued to the
recorder. I look back up, and I no longer have the ruler placed exactly
where it should be. I place it back where I think it should be.
WTH>>> This is one reason I use a talking watch. Since time to the second
is not crucial, except for fireballs, I can get a time to the nearest
minute with the press of a button, which BTW is actually loud enough to be
recorded on my tape. I also repeat it into the recorder since I have plenty
of time to spare :-)
while I fumble around with the rest of the process. Radio Shack sells them.
5:41:30 I stare and stare and stare at that region of the sky and
finally realize the meteor was over the peak of Ophiuchus.
WTH>> Practice will make that easier. Your 2nd time through the
constellations (a year from now) you'll remember a lot more!
I cautiously put the ruler down and reach for my red light and charts.
I turn on the red light, and in order to free up my hands for plotting,
hold the light in my mouth. I get stung on the tongue by an ant. I
spit the ant and several grains of sand out, then return to the chart.
WTH LOL>> I used the light in the mouth trick for a while. Very bad to do
that with a metal cased flashlight for the Leonids, Geminids, and
Quadrantids here in NJ. Now I currently use one of those "Snakelights"
around my neck, which allows mere contortion to point it in the right
direction, and also find the 18 pencils that I've lost scattered around me
while I am counting plot time.
5:42:30 An outburst of 15 simultaneous meteors occur while I am
staring down at my charts. By now I can't remember
which direction the meteor was traveling, or what the beginning and end
point was, if I ever had them well to begin with. I "plot" the meteor
just as the cat jumps on my lap and all my tools get scattered.
WTH>>> Well, my cats won't observe with me (afraid of bears) so I don't
have that problem. As for tools scattering, see my pencil comment above :-)
As for the 15 simultaneous meteors, ever hear of a guy named Murphy??
5:43:30 A magnitude -7 fireball appears while I am looking down to
gather up my pencil, chart, ruler and recorder.
WTH>>> See Murphy above :-)
But the most frustrating thing of
all, I think is getting home and not being able to accurately predict
the radiant drift for various minor shower radiants due to the
inadequacies of my charts. I still don't know what one grid on the
Atlas Bruno chart represents, in degrees, and my Petersons charts have
the RA and dec, but I can't translate that well into actual degrees.
WTH>>>
Trying to plot radiant drift on the Atlas BRNO charts is no good.
Suggestions:
1--Buy IMO Handbook when they are in print. Daily positions are on Atlas
BRNO Charts. ($20). It's worth the read, plus the master charts are
included.
2-- Look at NJAA Metor Page, there are charts with daily positions there,
adapted from IMO information. www.njaa.org
3 IMO Annual Calendar has charts for moon free showers for current year.
For showers wiped out by moon this year, look at the previous year's shower
calendar.
www.imodot net
4. Get a software astro program. I use Skymap, which allows me to set the
sky to any day or time, past , present, or future, and allows me to find
radiant location (interpolating IMO calendar positions, or using the excel
workbook I make every month)
Also lets me find radiant elevation, magnitudes of stars, and bunches of
useful stuff.
KY> So a few questions: If I hold my 12" ruler to the sky at arms
length, how many degrees of sky am I covering? It is approximately the
distance from Deneb to Altair. I know the rule of thumb about fist size
being 10 degrees and open hand being about twenty, but there can be a
wide variation there among individuals.
WTH>>> even this depends on how long your arm is. The problem is the Atlas
BRNO charts, since they are gnomic (in order to make a meteor path
straight) are inherently non-linear. The edges are stretched, so an inch in
the center is not the same number of degrees as an inch at the edge.
KY>> Also, do I need to join a guild or a lodge to get the secret
information contained within those plotting charts?
WTH>>Order a master set from Bob Lunsford ($4??) and you get the decoder
chart.
KY>> If I could
accurately measure distance on those charts, I wouldn't have to
aggravate Mark, Wayne, and others for current radiant positions. Or is
there some easier way that I'm missing altogether?
Try all the above. The $4 is the cheapest, the rest are a few bucks here
and there.
I'm sure Cathy, Bob, Mark, and others will also have some suggestions. hope
this helps!!
Wayne
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