(meteorobs) First dark sky hour after Full Moon

[Bill Godley]

Bruce and Wayne - thats the spirit!


----- Original Message ----
From: Bruce McCurdy <bmccurdy at telusplanet.net>
To: Global Meteor Observing Forum <meteorobs at meteorobs.org>
Sent: Wednesday, April 16, 2008 5:46:21 PM
Subject: Re: (meteorobs) First dark sky hour after Full Moon

    Thanks Wayne for the observing report under similar title. Your post 
reminded me to check the circumstances following the Full Moon. While at 
first blush the Lyrids peak happens in harsh moonlight with the waning 
gibbous Moon some 97% illuminated, the circumstances are slightly less bad 
than they appear due to the rapid southward progress of the post-full Moon 
at this time of year and the near-circumpolar nature of the radiant.

    Here in Edmonton for example (54 deg N.), Full Moon occurs in the 
morning hours of the 20th, while the Lyrids peak nominally occurs around 
22:00 MDT the very next night. The Sun sets at 20:47, and nautical twilight 
begins around 22:15 local time. The Moon, which is diving both down and 
below the ecliptic, will be at -24 deg. declination, and won't rise until 
23:06. So that should afford about an hour right at the Lyrids peak, with 
reasonable darkness, no moonlight, and the radiant rising through 20 degrees 
altitude.

    Circumstances further south will be less "favourable", but still might 
be better than hopeless.

    The following night the still-southbound Moon doesn't rise until 00:19 
MDT (on the 23rd), fully three and a half hours after sunset, leaving about 
a two-hour observing window ~24 hours after the peak. And by the 24th, the 
Moon reaches its lowest declination of the month (-28 deg.), opening a 
usable dark-sky window in the northern hemisphere even as Luna remains more 
than 80% illuminated.

    I hope to make it out one or both evenings of the 21st or 22nd. Once I'm 
there, I won't let a silly thing like a big fat moon stop me for at least 
another hour, although it'll be interesting to see what happens to my meteor 
rates as it ascends.

    Bruce
    ***** 

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