Last night we had nice, clear skies for the first time in a long while. I didn’t have a lot of time, but couldn’t pass up the opportunity, so I took out my Oracle for an hour or so of touring the galaxy. My 6” reflector stayed inside.
Seeing turned out to be excellent (rare for my location), and transparency was quite good. The air was absolutely still, and I quickly realized that this was one of those magical nights when I could go all the way to the 3mm setting on my Nagler zoom! I had no real observing plan, since I had not expected to have this chance at all. With these skies, though, I quickly came up with some ideas:
Saturn: With the zoom at 6mm (93x), Saturn was crisp and sharp, with the Cassini division clearly visible. There was only a hint of banding on the planet, although it seemed more evident in my 6mm Radian. One thing I have learned, though, is that very high magnification is required to get the most detail out with Saturn. I gradually stepped up the magnification with the zoom: Around 4.5mm (125x), the difference in brightness between the A & B rings became evident. This ring contrast was very apparent in my 4mm Radian. By the time I reached the 3mm setting in the zoom (186x), the image was just starting to soften. (Best views were at about 3.25 mm.) However, at this magnification, the view was large enough to make out subtle shading differences in the rings, and the C-ring became apparent at the ansae! The C-ring (or Crepe, if you prefer) was visible for just less than 1/3 of the rings’ circumference on each side of the planet. It popped in and out with seeing, and remained sharp for perhaps 2 out of every 20 seconds, on average. It was a definite, though difficult, sighting. This is only the second time I’ve seen it in the Oracle.
Jupiter: Suprisingly, Jupiter also took high magnification well last night. The best views were in the zoom at 3.5mm, and in the 4mm Radian. Unfortunately, the GRS was hiding on the back side of the planet, and there were no moon events scheduled while I was out, so it was mostly just an exercise in looking for detail in the equatorial bands. I didn’t spend a lot of time on it, although it was quite a nice view. (Why can’t the sky cooperate like this when there’s a transit?)
Castor: Encouraged by the sharp seeing, I got to thinking about the discussions in this [Televue] group about splitting Castor, and thought I’d give it a try. I’ve never bothered much with double stars (except a few of the well-known colorful ones), so I was actually rather surprised at the sight when I put Castor in the crosshairs with the zoom pre-set to 3mm. A quick tweak of the focus and--wow!--there they were, twin pinpoints of bright white light! Two stars where there used to be one! I backed the zoom down in increments of 1mm and found a clean split all the way to 6mm. I also tried my 7mm Nagler (80x), which maintained a clean split whenever the sky settled (about 1 second out of 5). I didn’t have a lower-power eyepiece handy to try any lower, but I don’t think it would have gone much lower without a lot of patience.
The Eskimo Nebula: While in the neighborhood, I decided to go looking for NGC2392, the Eskimo Nebula. This little planetary has eluded me for quite some time. It looks like a trivial starhop to find it, but despite several attempts, I had never managed to find it with any certainty. Last night I realized why--I never used enough magnification while searching. This thing is tiny!! I used the 7mm Nagler to find the “fuzzy star,” and then switched to higher-power eyepieces. The best views were in the 4mm Radian and the zoom at 3 to 3.5mm. The nebula itself showed up as a tiny bit of fuzz, like a little gray cotton ball. It had a mottled appearance, but a larger scope would be required to find any hint of an “eskimo” in the view.
Overall, it was another great night under the stars!
Clear skies to all,
Neil