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Re: (meteorobs) Re: Cetids
I am wondering if the video data might be useful here. I know the field I
am working with (10 degrees dia in reasonable focus, 18 degrees overall) is
small by meteor observing standards, yet I see as about as many meteors in
this small field electronically as I see in the single observer sky
visually over a given duration. Many of these are 4th or 5th magnitude and
may not be as representative of shower activity (more sporadics?), but,
then again, perhaps they represent more radiants with insufficient visual
numbers to identify an associated radiant and take them out of the sporadic
catagory. The main point is that once a meteor is recorded on video tape
it is no longer a fleeting "ephemerid" (if I might coin a term), gone
before you can nail its position to the sky; it is FOREVER (or essentially
so in all practicality). I agree with an earlier comment about video
meteor observing, you can quickly become buried in video tapes. Quite
true, but Hey!!, I love it!!! I have to confess, I am not the greatest
when it comes to reducing the data. I plot some on star charts and wish I
had more time to make some real progress on data reduction software. The
programs I wrote in 1960 to compute meteor orbits from doubly photographed
meteors won't run on these new-fangled machines. I have trouble just
reading a star catalog into an MSFC VCPP program, let alone finding star
positions automatically in .BMP format images. Sure this is all available
for the downloading if you are using .FITS images, but $99 computer store
video frame grabbers don't save files in .FITS format, so I guess I have to
write my own. On the other hand, might it be useful if some of the video
data was just reduced to plots on star charts? If so, someone just needs
to say yes to get me going. The problem is that it is not really possible
for me to look at a line I have drawn on a chart and conclude that it is
from such and such a radiant or shower, because I personally would not be
sure if it was from one place or another along its back projection. In the
method of meteor trajectory determination I used (not my invention but I've
forgotten the reference) the camera and the meteor trace together defined a
plane in 3-space, referred to as the Plane of Great Circle Motion. Cameras
at two well separated stations gave two distinctly different Planes of
Great Circle Motion for the meteor. The intersection of these two planes
was of course the path (or reasonable approximation to it) of the meteor.
To find what this path was you could go to vector analysis and make use of
what we called the Vector Cross Product, which produces a vector
perpendicular to the two "input" vectors in the cross product. If the two
input vectors are defined as the POLES of the Planes of Great Circle
Motion, then the output vector is (has the direction of) the trajectory
vector of the meteor. So I am wondering if instead of looking at this
line on the star chart, suppose I compute its corresponding Pole of Plane
of Great Circle Motion. This is a sort of invariant for this particular
meteor, but it seems that it is also related to the meteor's radiant in
that it has to be perpendicular to the radiant. Suppose we had a simple
way (a little program we could run on our PC's) that would let us compute
the, let's say,PGCM (Pole of Great Circle Motion) and output it in RA
degrees and Dec degrees. We could post that data to the web and anyone who
was inclined could take those numbers and run them through a little
correlation or matching of possibilities or whatever to see what radiants
actually show up from the combining of many observers data. (or is that
what you guys and gals are already doing somewhere, but I just haven't
caught on yet?). In any case, this seems to me like a good "starter" at
least for getting some potential value out of what otherwise might be just
a bunch of "sporadics" observed by single station video observers, and
maybe for visual observers who plot their data as well, although I sort of
assume there is a clearing house where people send meteor plots to have the
data extracted, (or do we just accumulate our own individually until we
perchance recognize something interesting showing up in our own data?).
Please anyone come back and set me straight on all this. I am having so
much fun with this little video system, all the while getting hundreds of
meteor images that I am not sure how to relate to the regular visual
observer data format, mostly because the format seems to require me either
to make an educated guess as to their shower membership or call them
sporadic, neither of which seems entirely satisfactory to me. I would like
to play in the game. I sure would appreciate some direction here.
Many Thanks,
All Best Wishes and Clear Dark Skies to All
Jim Wray
----------------------------------------
At 03:58 PM 10/20/99 -0700, you wrote:
>Well Lew,
>
>Telescopic observations would certainly be more precise! One would think
>that telescopic observers would feast on this complex as the combined
>rates are better than normal.
>
>Visual plots, while less accurate, can cover a much larger portion of
>the sky. What we certainly need is more people using both of these
>methods to help us understand the complexities of
>Taurid/Arietid/Cetid/Piscid radiants.
>
>Bob
>
>
>
>Lew Gramer wrote:
>>
>> >Experienced observers who plot are able to dissect the many
>> >radiants that are active simulteanously in this part of the sky.
>>
>> Actually, Bob, are even EXPERIENCED visual plotters really able
>> to completely untangle this skein of radiants?? (Other than you!)
>>
>> Or would more attempts by amateurs to plot meteors TELESCOPICALLY
>> at this time of year actually be more helpful?
>>
>> Lew, plugging away :)
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