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(meteorobs) Re: early Perseids



My two cents worth on the early Perseid observations.

From a radiant ephemeris I determined about a decade ago, the Perseids are 
typically at a radiant of about RA=44 degrees, DEC=+57 degrees on August 10, 
and RA=47 degrees, DEC=+57.3 degrees on August 12. The earliest I had computed 
the radiant's position, which could be confirmed by several photographic 
meteors, was for July 27, when the position was RA=27 degrees, DEC=+53.2 
degrees. My earliest computations of the radiant position went back to July 17, 
but no precise photographic data was available for a confirmation. The 
resulting position was RA=17 degrees, DEC=+50 degrees, which is a short 
distance from Phi Andromedae, amost right on the Cassiopeia border. For dates 
earlier than July 17, the radiant would continue backing up in the direction of 
Lacerta, while staying fairly close to the Andromeda-Cassiopeia border. 

Because of the high inclination of the comet Swift-Tuttle, which is the parent 
of the Perseids, planetary perturbations would not be exceedingly great. The 
same would hold true for the Perseid stream, although Earth could play a role 
in affecting the orbits of near-miss neteors. Although I cringe when I hear 
talk of early Perseids because of the relative stability of the orbit of 
Swift-Tuttle over several millennia, as long as the observer is confident the 
meteors are coming from the Andromeda-Cassiopeia region and not Perseus, and as 
long as observed rates remain extremely low, I think I can mentally handle 
this.  :-)

Gary W. Kronk