(meteorobs) 2013 Perseids from Central Alberta

BRUCE MCCURDY bmccurdy at shaw.ca
Tue Aug 13 22:10:59 EDT 2013


I've had four opportunities (so far) to observe Perseids from somewhere in Central Alberta. Each session has been in the 1.4 - 2.0 hours Teff range, so just a sampling on each night, with all sessions starting well after midnight local time. 

Aug 03: 1.5 hours, 10 Perseids seen, avg. mag. = +3.4, hourly rates = ~7.
Aug 07: 1.4 hours, 16 Perseids seen, avg. mag. = +2.1, hourly rates = 11.
Aug 11: 2.0 hours, 36 Perseids seen, avg. mag. = +1.5, hourly rates = 18.
Aug 13: 1.4 hours, 36 Perseids seen, avg. mag. = +1.6, hourly rates = 26.

While these raw numbers are not translated to ZHR, observing conditions on the first three evenings were fairly consistent and the ramping up of the shower towards the peak was clearly in evidence, with both more & brighter meteors observed on each successive session. 

After two solo sessions, on the evening of evening of Aug 11 I observed with fellow members of the RASC's Edmonton chapter, Ross Sinclair and Alister Ling, at our primary observing site at the Beaver Hills Dark Sky Preserve. That night featured a very promising start, especially a clump of four negative magnitude Perseids (plus 2 others) in a 3-minute interval, however rates dropped off soon thereafter, then clouds encroached. 

Pre-peak night Aug 11/12 was a complete write-off due to severe weather in the area, including multiple T-storms, destructive hail, and tornado warnings (which thankfully did not materialize). It would have been foolhardy to even attempt to drive for a clear hole, which likely would have been impossible to find in any event. 

Post-peak night Aug 12/13 saw heavy cloud over the city but three of us RASCals (Ross Sinclair, Sherrilyn Jahrig, & myself) headed SW of the city near Pigeon Lake where the satellite seemed promising. While we did find clearing skies, we had to cope with serious ground fog which forced us to raise our stakes and move to a second location a few km closer to the city, which was itself enveloped in fog all too soon. A third attempt was a washout even before we started. 

The ground fog was problematic in that much of the time the overhead sky was relatively decent with Milky Way clearly in evidence and SQM readings (taken in my usual fashion from the zenith) suggesting a limiting magnitude in the high 5's. However, there were varying but generally increasing amounts of atmospheric extinction at lower altitudes. I attempted to account for this by introducing a fudge factor under "field obstruction correction", but this is a best estimate only. I do know I saw 2 bright meteors low in the S which I adjudged to be about mag -1, even as there were zero stars to be seen in that direction so they very likely were near-fireballs. 

Overall, I saw just one fireball, a -4 bronze flash low on the northern horizon on Aug 7 which left a 4-second smoke trail. No bolides were heard at any time, other than the standard format of outbursts from neighbouring astronomers. :) 

I had held out some hope of going out again tonight but the optimistic Clear Sky Chart forecast has turned into another washout. CSC is in a bit of a slump at the moment, at least in these parts.  

Overall, I saw 98 Perseids over 6.3 hours Teff, and spent rather more time than that driving to and from the various dark sites. My 26th year of observing Perseids was far from the best, but as always, well worth the effort. 

Observing summaries of all sessions were submitted to http://imo.net/live/perseids2013/ in my usual fashion.

Bruce
***** 

   




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