[Prev][Next][Index][Thread]
(meteorobs) Singing the Lyrids
Hi folks, it's been a long winter since the Quadrantids, but once again my
location high in the northern hemisphere led to moderately favourable
conditions to observe the Lyrids.
In his invaluable weekly meteor update, Bob Lunsford said:
> The moon reaches its last quarter phase on Wednesday April 23. For this
entire period the moon will be present in the morning sky, limiting the
activity seen during this time of night.
With the greatest of due respect to Mr. Lunsford, as a long-time lunar
observer, lunar *avoider* (aka deep sky and meteor observer), and amateur
orbital mechanic, I must point out that not all third quarter moons are
created equal. Many/most of you know this already, including Bob himself who
is after all issuing global forecasts, but the local circumstances are
always a point worth considering.
The third quarter moon is in the spring, always near the lowest part of the
ecliptic; as experienced in "extreme" latitudes such as here in Edmonton,
Canada (53.6 degrees north), this has a major delaying effect on moonrise.
(In the southern hemisphere where it is now autumn, observers will have been
observing the Harvest Moon effect of an extremely high waning gibbous moon.)
Furthermore, we are approaching that point of the 18.6 year cycle known as
the regression of the nodes (next maximum 2006) where the 5-degree tilt of
the Moon's orbit is piggybacked atop Earth's own 23.4-degree inclination,
resulting in some extreme declinations and, in the current instance, a
further delaying effect on moonrise times.
Net result was that on April 22, a gibbous moon still 26 hours before third
quarter phase was at -27 degrees DEC and did not rise here until 3:40 a.m.
MDT, more than two hours after local midnight. I therefore was able to get
in three hours of dark sky observation of the Lyrids in the morning hours,
during which time the radiant soared from 32 to 57 degrees altitude.
All that said, my "dark sky" offered a few challenges other than moonlight.
A band of aurora persisted in the northeast, blocked in places by the "dark
nebulae" of some heavier cloud. The aurora threatened at times to take over
the sky, gently rippling with potential energy which on this occasion at
least, never quite rolled up its sleeves and went to work. The brighter
portions of the aurora cut the limiting magnitude in half or more, and its
unpredictable subtle movement was quite distracting to the task of watching
for the unpredictable sudden movement of meteors. Cirrus clouds washed in on
the prevailing westerlies, which were apparently not on speaking terms with
a freshening ground breeze from the southeast. To the south was the skyglow
of greater Edmonton -- seen from the outside for the first time in quite a
while -- and, shielded by my car, an obnoxious ~1,000 W. yard light of the
type that is unavoidable on country roads around here. The zenith was mostly
clear, other than it was the evening's flight path for several jets and
featured a number of lingering contrails So despite my efforts to get out of
town, my limiting magnitude ranged from 4.0 to 5.0 for the most part.
But I did go out to observe atmospheric dynamics, so why should I complain
about the three-ring sideshow? Besides, it took the sight of a single meteor
to realize that it was worth the effort. I was in fact treated to a half
dozen very nice Lyrids within the first quarter of my three-hour session,
which resulted in high hopes but in the end turned out to be the best
portion of the evening. Indeed, I saw only another half dozen meteors,
including only four Lyrids over the remaining two hours plus, resulting in
very skewed ZHRs. I remained alert through a favourite pastime of inventing
my own constellations, but this did nothing for activity rates. Results are
tabled at bottom, with apologies for the crudeness of the method, which is
still "under development".
The meteors that I did see were of high enough quality to remind me why I do
this. 7 of the 10 Lyrids were of first magnitude or brighter. Most displayed
brief trains, blurs on the order of a fraction of a second. Several were
bluish, and one beauty was a distinct orange.
A final observation is that for the second year in a row the Lyrids were
practically radio silent. I used my tried-and-true car radio technique to
monitor the shower, and heard nothing in the way of decent hits. In the case
of the Perseids, Leonids and Geminids, to name three, I typically get two or
three radio "hits" for every visual observation, with occasional
simultaneous events. This time I got nothing whatsoever in the way of decent
radio "hits" in over an hour of direct monitoring. My home radio observatory
also recorded no activity out of the ordinary, to the extent that I'm
worried my equipment is malfunctioning. Did anybody get good radio Lyrids
this year?
Alas, that also means I have nothing to report on pi Puppids, either
visually or radio.
regards, Bruce McCurdy
*******
Summary
0640-0740; Teff 58 mins; LM 4.8; 6 Lyrids 0 Spo; ZHR = 67
0740-0840; Teff 57 mins' LM 4.9; 3 Lyrids 1 Spo; ZHR = 22
0840-0940; Teff 60 mins' LM 4.7; 1 Lyrid, 2 Spo; ZHR = 7
*******
Detailed count and magnitude distribution
Lyrids Sporadics
-2 -1 0 1 2 3 Total
0640-0650 0 0 0 0 1 0 1 0
0650-0700 1 0 0 1 0 0 2 0
0700-0710 0 0 1 0 0 0 1 0
0710-0720 0 1 0 1 0 0 2 0
0720-0730 0 0
0730-0740 0 0
0740-0750 0 0
0750-0800 0 0
0800-0810 0 0 0 0 0 1 1 0
0810-0820 0 0
0820-0830 0 1
0830-0840 0 0 0 1 1 0 2 0
0840-0850 0 0
0850-0900 0 0
0900-0910 0 1
0910-0920 0 0
0920-0930 0 0
0930-0940 0 0 1 0 0 0 1 1
Totals 1 1 2 3 2 1 10 3
*******
The archive and Web site for our list is at http://www.meteorobs.org
To stop getting all email from the 'meteorobs' lists, use our Webform:
http://www.meteorobs.org/subscribe.html
Follow-Ups: