5 April, 2025

 

Crater Thaetetus

The sky was mostly clear, but very bright and transparency was low. The Moon was at about 60% full waxing. Bright enough to cast visible shadows. There was also a lot of moisture in the air. The lights on the side of the truss company, about 1/2 mile away, had halos around them. Luckily no dew formed while I was out. Seeing was probably Antoniadi 3, possibly 3.5. I wasn't able to push magnification past 156x without turning Jupiter into a fuzzball of light. I was hoping it was better because I wanted to check collimation after the 'scope fell last time I was out. 

With the sky so bright, I made Jupiter my initial target. I was only able to resolve the North and South  Equatorial Bands. Seeing was unsteady enough that at times they disappeared. The Galilean moons were easily visible. I had read that using the Moon filter on Jupiter can sometimes help bring out more detail, so I gave that a try. The only effect for me was a dimmer view. I spent quite a while on Jupiter, trying different eyepieces but not really getting a better view.

 I moved on to the Moon, hoping to do some sketching. I just started looking along the terminator from south to north. A small crater SE of Cassini caught my eye. It's stark simplicity compared to the bordering regions made it seem like a good place to practice sketching. The two smaller craters in the floor and the one smaller one immediately outside the rim were also interesting. I sketched it using the 13 mm Plossl eyepiece. The sketch doesn't do justice to how bright the illuminated sides of the smaller craters were. 

Using the S&T Mirror Image Field Map, I identified the crater as Thaetetus.  Using the 17mm eyepiece the view included Aristoteles, Autolycus, and Archimedes. The Caucasus was also in the field of view. The image did waver some, making me sketch as it settled. At some point a breeze came up. I didn't think it was that much, but it caused a lot of vibration.