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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