[AZ-Observing] Re: Images of Occultation of Venus

15480 Empire Rd.
Benson, AZ 85602
hm ph: 520-586-2244
I just had a chance to view your exquisite video of the Venus occultation, Tom 
(and, I assume, Jennifer!). Interesting is the spillover (irradiance, according 
to Gene) of Venus' image onto the moon's surface in your imagery. I understand 
some people saw the effect visually though I did not, mostly, I suspect because 
I had a large enough image scale with my 13-inch f/5.5 telescope and 16mm 
eyepiece. 
One effect that occurred to me to try and see was a Venusian green flash as the 
last remnants of its disk disappeared behind the moon. Comments as to why or 
why not the phenomenon should or should not have been expected would be 
appreciated. The moon doesn't have an atmosphere, of course, while the earth 
does and is the reason why we see the green flash happen with the sun from our 
vantage point on earth. Venus does have a very thick atmosphere and even though 
it is disappearing behind the sharp edge of the atmosphereless moon I would 
have thought that some effect should have been seen. 
I was fascinated by how easy Venus was able to be seen after the sun had risen, 
especially with the moon being used as a reference, and also the clouds, when 
they were our of the way! 

Clear skies, 
Wayne (aka Mr. Galaxy)


---------- Original Message ----------
From: Tom Polakis <tpolakis@xxxxxxx>
To: AZ-Observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Images of Occultation of Venus
Date: Thu, 23 Apr 2009 0:45:46 -0400

Here are some images of the beautimous Venus occultation that occurred this 
morning.

http://www.pbase.com/polakis/venusmoon0409

I used a 70-200mm lens with a 20D, and then attached the 20D to a TV101 
refractor.  The Webcam was in the 10" at prime focus, and I recorded ingress, 
but missed egress.

Thanks to Rick Tejera for the excellent description.  I don't have much more to 
add.  All aspects of the event were pleasing views through the little Pronto, 
and the naked eye view was great as well.

Post-processing the video, I see that the entire ingress took roughly 4800 
frames, which would correspond to 80 seconds at 60 fps.

Tom
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