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(meteorobs) Re: Are Sporadics Constant?

John and All:

I was hoping that some radio enthusiasts would step in and answer your
questions. Since only one response has been forthcoming I will throw in
my 2 cents worth.

There is no easy way to determine exactly what your system is recording.
During major showers a majority of the activity would be from that
shower should the radiant be at a sufficient elevation above the
horizon. On all other nights a great majority of the activity would be
from sporadic sources.

Studies have shown that the annual sporadic distribution peaks in
September and is lowest during March as explained by Kim Youmans.
Analyzing data on the order of months and weeks would probably exhibit
variations beyond statistical limits. It would be quite possible that
these variations are caused by sporadics alone and are totally unrelated
to shower activity. 

The bottom line is that there is no way to precisely know if you are
recording shower members or sporadic activity. After obtaining several
years worth of data using the exact same system the data should reveal
some interesting patterns which could alert visual observers to
concentrate on these particular nights.

Hopefully others, more knowledgeable in this subject that I, can clarify
the situation in detail.

Clear Skies!

Bob Lunsford

 


"John R. Meyer" wrote:
> 
> Dear Meteorobs Net:
> 
> Our radio observatory is at the point where we are collecting solid data 95
> per cent of the time.  System specifications and data for January, 2000 were
> posted to Meteorobs Net on Fri., Feb 18, 2000 and in the Meteorobs Digest
> V3, #298.
> 
> It appears that our next step in data reduction is to determine the number
> of background sporadics and subtract this from total reflections observed.
> Presumably the residual will be attributable to meteor showers.
> 
> It may be, however, that determining background sporadics will not be
> trivial.  Unlike the situation with visual observations, we have no easy way
> to determine if a given reflection is due to a sporadic or is part of a
> stream/shower.
> This occurs because we collect no data on the radiant.    We only determine
> total activity as seen by our directional antenna.  It will respond to any
> signal which obeys the laws of specularity.  That is, it will pick
> up any signal where both the transmitting and receiving antennas can both
> "see" the meteor trail at the same time, and where our antenna is at the end
> of the path where the angle of incidence of the VHF signal upon the meteor
> trail is equal to the angle of reflection.  On average, this accounts for
> roughly 3,000 meteor events in an normal 24 hour period.
> 
> Several question arise with regard to this:
> 
> 1.  If we are able to determine sporadic activity for a given hour during
> the day, or month, are these data valid for the same hour of other days,
> months, and years?  That is,  the level of sporadic activity constant for a
> given hour, within statistical limits?  Are there monthly variations in
> sporadics that are statistically significant?  How about yearly variations?.
> We know,  of course, that there is a cyclical pattern of radio meteor
> activity over the 24 hour period due to the earth's rotation and its path
> around the sun.  Our data clearly show this 24 hour activity pattern.
> 
> 2.  How do we actually determine background activity?  Some meteor showers
> appear to be characterized by very low activity over many days.  How can we
> be sure we really are looking at sporadic activity (true background "noise")
> without contamination by weak and/or even unknown long term meteor showers ?
> 
> I would very much appreciate input on the above questions, along with any
> suggestions on literature that might deal with this.
> 
> Regards, John Meyer
> Van Andel Creation Research Center
> Chino Valley, AZ
> 
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