Quote:
Originally Posted by ngcles
Hi All,
Just a quick note to say that the seeing in Sydney tonight is very good. 
I've just seen Sirius B near zenith for the 3rd or 4th time in my life using a 12" f/5 dobsonian newtonian at x428 -- seen with little difficulty.  Splitting Nu Orionis was a doddle at only x140 and Saturn looks superb, despite its fairly low altitude at 8.20pm.
Get amongst it while you can, moonlight or no! Imagers take note!
Best,
Les D
Contributing Editor
AS&T |
Hi Les,
Seeing here last night was pretty reasonable. I spent my time on the Moon and Saturn with some great views. Never thought to try the PUP last night, although I tried unsuccessfully once recently at Coonabarabran under marginal seeing conditions.
Living right on the Southern side of Tuggerah Lakes (50 metres) I usually get very good seeing at Zenith and to the North looking across the lake with over 10km of water underneath my line of sight.
Tonight the seeing was better than last night (9/10) so I figured to give the PUP a try. It was pretty easy in the 18"/F4.5 at 420X (5mm Pentax XW), notwithstanding it was right beside the diffraction spike. I then swung to the moon and got some excellent views at 525X (10mm Pentax XW in 2.5X Powermate). I was able to see 8 Craterlets in the floor of Plato with another that I know of just North of the East Wall Pit hidden in shadow and not visible at this moon phase. The Rille down the middle of the Alpine Valley was also very prominent. I then went to Gamma Centauri and was able to split it at 525X. I then went to Saturn and got one of the best views I have ever had of it. I was still at 525X as the scope powered over to it and I expected the view to be pretty mushy, it was sharp as. I spent quite a bit of time on it at 525X. What is observable of Cassini Division due to the ring plane inclination, was easily visible like it had been sliced through with a router. Clear black space. The crepe ring was easily visible as was the Encke Minima. Surface banding and detail on the planets' disk was stunning. I figured, "this might cop a bit more". I removed the 10mm Pentax XW and stuck the 8.5mm Pentax XF into the powermate for 620X. The view held up beautifully, this time with Encke Division popping in and out just where the rings appear most face on. I then decided to try more power. I put the 7mm Pentax XW into the focuser for 750X. The view was still very nice in moments of steadiness but just starting to fade in and out a bit. Still an outstanding view. All the detail that was visible at 620X was still there when the air was still. I then decided to go all out. I stuck the 5mm Pentax XW into the Powermate for 1050X. It held up pretty well but just dropped out a little too frequently and servocat was struggling to keep the target in the FOV. However it was still a very nice view and in no way "mushy".
One of the best nights of high power observations I have ever had and ever likely to have. Easily the best views I have ever had of Saturn. It is good when everything comes together and all falls into place at the same time. Excellent seeing, good optics, and last but not least a well cooled and collimated telescope. Unfortunately I have to work tomorrow otherwise I would have stayed out longer, much longer
.
Cheers,
John B