[Lvas] Observing Aug 1

[David Blanchette]

Well, if you weren't out last night watching Jupiter, you missed it all!

I decided to try working with the club's 24" telescope again last 
night.  My laser collimator having died (and Scope City out of 
stock), I collimated visually.  I wound up with pretty good star 
images, and could even see the diffraction spikes from the secondary spider.

Jupiter climbed above a neighbor's house by 9:30, but I had to wait a 
half hour or so for it to get high enough that the heat from the 
rooftop was not so disturbing.  At first, it appeared as a typical 
"Jupiter and its four moons" situation.  About 10:30, I noticed what 
looked like a moon shadow on the planet.  I punched up the power and 
noticed a little bump on the limb.  I began to wonder if I was 
actually seeing the four moons.  So I checked my Skymap software, to 
see what was going on, and found that the "fourth moon" was actually 
a star, and Ganymede had been hiding behind the planet.

On a whim, I checked CalSky, which listed the following events:

22:18  Europa shadow ingress
22:28  Red Spot Transit
22:32  Ganymede occultation reappearance
22:56  Europa transit begin
00:22  Europa inferior conjunction
00:28  Black Spot transit (calculated based on info from SpaceWeather.com
00:37  Io eclipse begin

Having seen the Black Spot on Thursday, I wanted to see it again, 
especially with the larger scope.  So I decided to make a night of it.

The seeing was good for the most part.  A lot of moving the telescope 
to let Jupiter drift across the field, waiting for those 10 to 15 
seconds of clarity.  I could see Europa's shadow quite easily, and 
used it as a gauge for clarity and focus.  When I would see it 
clearly, I would look for the Red Spot and for Europa.  I found a 
blue filter helped with the Red Spot.  I think I could make out 
Europa against Jupiter, but it was very difficult to see.

About 23:45, I was able to pick out the Black Spot.  I don't know 
whether it has dissipated, of it the seeing really wasn't as good as 
last Thursday, or if the telescope collimation was not what I'd 
hoped, but the spot was much harder to make out, despite having four 
times the light bucket.

All in all, a pretty good night.  And to top things off, I think I 
have the scope working to the point where I plan to bring it out to 
the Red Rocks event on the 15th.  This would be the first time this 
scope has been out to the public in how many years?

-- David