[AZ-Observing] Good Seeing, Saturn's Colors, and the Jovian Moons
- From: Tom Polakis <polakis@xxxxxxx>
- To: az-observing@xxxxxxxxxxxxx, amastro@xxxxxxxxxxxxxxx
- Date: Sat, 25 Jan 2003 11:30:29 -0700
Frank Kraljic called late Friday afternoon to mention that the seeing
forecast recently mentioned by Jeff Hopkins
(http://www.cmc.ec.gc.ca/cmc/htmls/seeing_e.html) indicated excellent
seeing was possible. We had a chance to check for ourselves later that
evening when Frank brought his 10-inch scope to my backyard. Frank and I
have nearly identical Spooner mirrors, and set up side by side. Other than
the dust samples from various desert observing sites residing on my mirror,
the images in both telescopes were comparable: very good. I got an image
through Frank's telescope to prove it:
http://www.psiaz.com/polakis/videoastro/20030124/saturn_2a.jpg
Most of what you see in that image was apparent visually on Saturn. We
spent a lot of time working on the color balance. We find that many of the
images present Saturn in stretched colors. Since we spent as much time
observing Saturn as we did imaging it, the true colors were fresh in our
minds. Saturn's colors are mostly shades of yellow through brown. The A
ring is gray, and the B ring is a brighter yellow than the globe. And the
C ring is only slightly brighter than the surrounding sky.
We moved on to observe and image Ganymede. While Jupiter was limited to
about 500x, the small satellite just kept getting better up to 1000x. We
both saw the same detail on Ganymede, which included a dark albedo feature
north of the crater Tashmetum near 270 degrees longitude. Each of the
Galilean satellites are unique worlds at 1000x. I know better than to
claim we saw erupting volcanoes on Io. Callisto is notable for its dark
gray disc, and Io for its orange color, while Europa is just tiny.
Ganymede yielded some detail on the Webcam images, but they required
extensive processing, and I need to scrutinize them further before putting
them up.
Tom
---
Tom Polakis
Tempe, AZ
Arizona Sky Pages
http://www.psiaz.com/polakis/
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