Tuesday, October 25, 2011
Friday, October 21, 2011
I was surprised to see a very dark spot a little bit east of center on the north equatorial belt at JD 2455856.5754. It looked a little fuzzier than a moon shadow, and possibly slightly elliptical. It moved in the same direction as Jupiter was rotating. Experimenting with my collection of gel filters showed that the spot got much harder to see through a magenta filter. Vivid pink, red and orange also decreased contrast. Green may have enhanced contrast slightly. I hypothesize that the spot was dark red in color.
I also saw the Great "Red" Spot--in the words of a colleague, it looked like an empty area.
Both the dark spot and the Great Red Spot looked very good in my colleague's 8" F/6 with a binoviewer.
Update: I looked on Cloudy Nights. The dark spot is nicely seen here. I am pleased to note that I got the color and shape right with my filter swapping technique: it's definitely dark red and oval in the photo. These spots are apparently known as "barges". More information and links here.
Tuesday, October 4, 2011
For various reasons, I haven't been doing that much observing for the past half year or so. But I've been out twice this week looking at the moon with my 8" Coulter. I can't really do deep space viewing given the lights that have cropped up in a nearby grassy area, but the moon is all the better for it. I've been observing in and not far from Mare Serenitatis: Posidonius and Cassini were particularly striking, as was Ryma Hyginus together with its central crater. I am finally getting good use of my 5mm ortho eyepiece--it's really nice for the moon, giving a sharp 160X image.