(meteorobs) Obs: 12/13 August 2007

[pmartsching at mchsi.com]

13 August 2007 02:00-10:00 UT (CDST 12/13 Aug 9:00pm - 5:00am)

Paul Martsching
Long: 92 deg 08 15 W  Lat: 36 deg 50 00 N  Elevation: 1,024 feet
SE Douglas County, Missouri (ESE of Ava, Missouri)

(Late because of computer problems - the hard drive died.)

Meteors by hour:
UT           ANT   KCG   PER   UPE   Spor   Total  Lim.Mag.             
02:00-03:00   -     2     8     -      4      14     5.7
03:00-04:00   -     -     8     -      3      11     6.2
04:00-05:00   -     2    10     -      1      13     6.2
05:00-06:00   -     -    15     -      2      17     6.2
06:00-07:00   -     -    30     -      4      34     6.2
07:00-08:00   -     1    33     1      4      39     6.1
08:00-09:00   2     -    27     -      2      31     6.0 
09:00-10:00   -     1    36     -      5      42     5.9
--------------------------------------------------------
8 hours       2     6   167     1     25     201

Magnitude distribution:
Antihelion: 0, +2
Kappa Cygnids: 0, +1(4), +2
Persieds: -6,-5,-4(2),-3(6),-2(7),-1(10),0(21),+1(28),+2(34),+3(41),+4(12),+5(4)
Sporadics: -2, +1(3), +2(4), +3(14), +4, +5(2)

The Upsilon Pegasid was 07:08 UT, mag. -2, fat, yellow and of moderate velocity.
It travelled 4 degrees; 3 degrees were inside the Square and one degree beyond
Alpha Andromadae (corner star) which it passed by less than one degree.  Both
Dave Oesper and I thought UPE the instant we saw it - remembering the 1980's
when this shower was fairly active.  The typical UPE was fat/broad, yellow, of
moderate velocity and often traveled a short path.  This shower seems to be
nearly dead for some years now - I see only one or two possible UPE's a year
now, even if observing many hours around the date of maximum.  (Of course one
can never completely rule out a sporadic meteor having the characteristics of a
shower just happening to be lined up with the radiant.)  

Conditions each hour:
UT           direction alt     sky     wind   temp      aver lim mag
02:00-03:00  NE        45 deg  clear   calm   85 deg F     5.7
03:00-04:00  NE        45      clear   calm   82 deg F     6.2
04:00-05:00  NE        45      clear   calm   78 deg F     6.2
05:00-06:00  NE        45      clear   calm   74 deg F     6.2
06:00-07:00  NE        45      clear   lt&var 73 deg F     6.2
07:00-08:00  NE        45      clear   lt&var 73 deg F     6.1
08:00-09:00  NE        45      hor.hazelt&var 73 deg F     6.0
09:00-10:00  E1/2;W1/2 45      "clear" lt&var 72 deg F     5.9

No more than one minute per hour not observing (watering the grass, etc)

Note: I can no longer perceive a sky being better than 6.2 no matter how good
the observing site.  I guess it just comes with age.

50% of the Perseids had at least very brief trains.  The longest duration train
was 7 seconds from a -6 fireball; but this meteor dived down to the Northern
horizon, so its train duration was greatly shortened by atmospheric extinction.

The Perseids showed no colors other than yellow and orange:
White: 64%  Yellow 23%  Orange 13% 
  
My best Perseid hour regardless of beginning or ending time was 06:45 - 07:45 UT
(01:45-02:45am CDST) when I saw 43 Perseids.  I don't know if this was the time
of the peak or just statistical happenstance.  

The past few years whenever the Moon has not been a major problem, Dave Oesper
and I have been traveling to see the peak night of the Perseids under good sky.
 We have had to travel several hundred miles each year and it doesn't always
work out.  In spite of the best weather forecasts, we sometimes get fogged out
around 3:00 am CDST.  If I'd stayed in Iowa, my record of seeing the Perseid
peak under good conditions about once in fifteen years would continue. 

The weather this year in Iowa has been exceptionally bad for meteor observing.
Even when forecasts say "clear" it often means very hazy, very cirrusy, somewhat
foggy or even partly cloudy. I have missed a few nights because I thought it
best not to risk firing up my cold/allergy related sinus headaches (especially
in Winter and early Spring) and because of hernia surgery in July.