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(meteorobs) Re: Meteor Activity for the Week of December 24-31, 1999

I wonder if a study has ever been attempted to verify average magnitudes
before verses after midnight?

Bob


"Kim S. Youmans" wrote:
> 
>      At the risk of stepping out of my league, I would like to add that
> observing before midnight does have one advantage over later hours...the
> meteors that ARE seen are on average brighter than post-midnight.  Chances
> of seeing fireballs diminish a bit as one goes from 6 pm to 12 am and
> beyond.   So while one may see fewer meteors, the ones seen tend to be more
> of a treat!
> Kim Youmans
> 
> Robert Lunsford wrote:
> 
> > The moon has just passed its full phase and is now waning toward last
> > quarter. This will free up the early evening hours for observing without
> > lunar interference. Typically at this time of night one would see an
> > average of 5 sporadic (random) meteors per hour from dark rural
> > observing sites. Once the moon reaches last quarter on Wednesday,
> > December 29, the entire evening will be free of moonlight. At this time
> > it is often asked if it is better to watch before midnight in dark skies
> > or to endure lunar interference during the morning hours. On most
> > occasions observers would see more activity during the morning hours
> > despite the presence of moonlight. Meteor rates are stronger after
> > midnight and the last quarter moon is much less intense than it is
> > when near full. This allows rural observers to achieve limiting
> > magnitudes of 6.0 when facing areas of the sky away from the moon.
> > Sporadic rates would be near 10 per hour under such conditions so
> > meaningful data can be obtained despite the presence of moonlight.
> >
> > For observers limited to watching during the early evening hours, the
> > only known radiant above the horizon at this time would be the Chi
> > Orionids. During this week this radiant is located in south-central
> > Gemini near the position 6:45 +20. The radiant is just below the horizon
> > at dusk rising higher into the eastern sky as evening progresses. It
> > reaches the meridian (due south) between midnight and 0100 and is best
> > situated for viewing at this time. This shower produces meteors of
> > medium-slow speed with typically 1-2 shower members per hour this time
> > of year.
> >
> > The Coma Berenicid activity continues this week with the radiant lying
> > in western Coma Berenices near the position 12:12 +22. The radiant rises
> > near midnight therefore no activity can be seen from this shower during
> > the evening hours. The best rates from this shower will occur just
> > before dawn when the radiant lies high in the south. The Coma Berenicids
> > are swift meteors with many persistent trains. The moon is located near
> > the radiant early next week so be sure to face away from this area,
> > perhaps toward the north or the southwest to avoid direct moonlight and
> > the loss of night vision.
> >
> > During my Geminid observations I happen to notice several swift meteors
> > each morning coming from an area near the Leo-Virgo border. These
> > meteors are related to the Apex radiant which lies 90 degrees west of
> > the sun and produces 1-2 meteors per hour on average. This radiant is
> > now located in western Virgo near the position 12:30 -3. This is close
> > to the famous 3rd magnitude double star Porimma or Gamma Virginis. This
> > radiant also rises near midnight and is best seen just before dawn.
> > Enhanced Coma Berenicid rates could be due to inclusion of these apex
> > meteors since the velocities are similar and the radiants are fairly
> > close in the sky. Once the moon is out of the picture it is suggested to
> > face a bit more toward these radiants to aid in shower association.
> >
> > Finally, there have been scattered reports of activity from the
> > constellation of Lynx during this period. This faint but large
> > constellation is located in the area between the Big Dipper and Gemini.
> > Any possible activity from this area would possess medium velocities.
> > Any confirmation of such activity or lack of activity would be important
> > in assisting us analyze activity for this particular time period.
> >
> > Merry Christmas Everyone!
> >
> > Bob Lunsford
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