Triesnecker rilles

[davidc135]

Beautiful seeing although still very light outside. Hopefully the Triesnecker rille system will show well in the 81/2'' Dob later on, and Plato and the Alpine valley too. Imight be a bit early for Plato, though.

David

Edited April 28, 2023 by davidc135

[Stu]

Thanks for the heads up David.

I had no intention of observing tonight, but having seen your post, the clear skies and the beautiful Moon, I put my 8” f8 out for a look.

As you predicted, Treisnecker Rilles looking very clear, and additionally Hadley Rille and parts of the Alpine Rille too. Wonderful views using my MaxBright IIs, once I got them to focus 🤪

[davidc135]

Some nice views this evening with seeing very good at times. Triesnecker J and H were easy whilst the rilles showed well extending to the higher ground to the south at best moments. Now and then I caught all of the Hadley rille but the Alpine rille is tough. I repeatedly saw a sliver next to the square and a little above it but I think that was probably some craters.

Interesting pale albedo effects in Plato with sunlight only reaching the base of the Western wall. I suppose it's well known but there were great jagged strips of pale floor extending eastwards from the wall halfway across the crater floor. Hmm, I don't think it was direct sunlight but the jagged outline suggests mountain shadows.

Hopefully the clouds will clear again but that's likely it for tonight. Cant forget Birt rille which was difficult when viewing through some tree twigs, maybe not surprisingly. It really picked up when the Dob was moved to a clearer spot.

Maybe I should invest in a couple of really good eyepieces.

Ancient but well made Plossl plus Barlow giving x280 throughout.

David

 

Edited April 28, 2023 by davidc135

[Mr Spock]

Seeing not so good here so I had to back off the magnification, settling on x217 with the 12". I could see the rilles plus a row of three small craters to the west of Hyginus A. Not bad for the wobbly conditions.

Those rilles gave me a chance to test some of my eyepieces - 7mm Nirvana, 7mm Ortho, 18mm ortho + x2.5 Powermate. Not much in it at all, I could see the same features in all of them.

[davidc135]

Hi Stu, I wonder when you were out yesterday whether you noticed the light stripes on the still in shadow floor of Plato. Here's a sketch done from flawed memory. The two lozenges were very directional and well defined and easy to see. As time went on and dawn in the crater approached, the stripes grew larger until they united at their western end. But it wasn't direct sunshine. Then the clouds came.

Because they seemed connected with the sun's position I don't think they are topographic albedo features but I can't think how the sun could be illuminating parts of the floor indirectly. Any ideas?

I'm not too sure of the terminator's position but the crater floor is reasonably faithful. It was obvious.

David

Edited April 29, 2023 by davidc135

[davidc135]

The pale lozenges on Plato's floor perhaps have an ordinary explanation but they seemed extraordinary.  David

Edited April 29, 2023 by davidc135

[Stu]

6 hours ago, davidc135 said:

The pale lozenges on Plato's floor perhaps have an ordinary explanation butthey seemed extraordinary.  David

Hi David,

I believe I was observing around that time, and checked on the NASA lunar simulator. Do these images look familiar, and how do they relate to what you were seeing? I just observed the jagged shadows of the crater wall cast on the floor. Let me know.

This is the link to the simulator in case you are not familiar with it. It seems very accurate on even quite subtle illumination effects.

https://svs.gsfc.nasa.gov/5048

[davidc135]

If the seeing on the 28th was good, this evenings was even better. I should think the views were the most detailed I'd ever seen; from the Plato craterlets all the way up to Clavius. Everywhere there was that extra level of fineness.

A friend had sent me an Astro tech 4mm wide angle ep which I hadn't had a chance to use until now. Images were crisp and clear at x400, in fact clearer than at x280. I don't know that I could see more detail but certainly just as much and more comfortably.

David

[davidc135]

Hi Stu

Yes, they are very close. The clouds came over between images 2 and 3. Thanks for the images and clearing that up.  David

[Stu]

8 hours ago, davidc135 said:

Hi Stu

Yes, they are very close. The clouds came over between images 2 and 3. Thanks for the images and clearing that up.  David

Good to resolve the puzzle 👍.

This is a crop from a smartphone image taken at 21.55 which shows the effect.

[Roy Challen]

On 28/04/2023 at 22:30, Mr Spock said:

back off the magnification, settling on x217

Backing off to x217! I wish...!

[Roy Challen]

4 hours ago, Stu said:

Good to resolve the puzzle 👍.

This is a crop from a smartphone image taken at 21.55 which shows the effect.

Smartphone image? Wowsers!