Observing Session 28-29th Dec '08

Just some notes from last night / this morning...
Last night I spent a few hours observing the main DSOs in Orion, Gemini and Ursa Major. I then went to bed and set the clock for 4am to catch Saturn. The rings of Saturn are almost edge-on to us now - approx 0.8degree angle.
www.visualastronomy.com/2008/11/saturns-...-nearly-edge-on.html
Despite the shallow angle, the rings are still easily visible as a pencil thin bright light like someone drew a bright yellow line across the planet. More detailed observations at higher magnification reveal the shadow of the rings across the disc. Because of the shallow angle, the dark line of the ring shadow is directly adjacent to the bright "line" of the rings. At moments of steadier seeing (on a not-so-good night) and high magnification I could detect the curvature of the rings at their outer extremities. Subtle cloud bands were also visible on the disc.
I took advantage of the altitude of Ursa Major and Can. V. to take a peek at M51, M97, M101, M108 and a few other DSOs.
M51 was spectacular! First time seeing it with this scope. Spiral structure was clearly visible without any need for adverted vision. M101 was also very good. I wasn't sure how good this object would be - it is a large face-on galaxy which makes it a bit harder to see the spiral arms due to the size and faintness of the object. My recent purchase of a 31mm Nagler (thanks William) helped here and it has quickly become my favourite eyepiece (due to the long focal length of the 16" SCT). I'm glad to say that the spiral arms of M101 could still be seen even from my hazy skies here. M97 showed the "monkey eyes" and takes a UHC filter very well. M108 was also a well worth a look.
Tired now (6am) so going back to bed.
Michael.

nice effort michael you stood up for saturn

31 Dec at 00h50 UT, Titan will come back from behind the planet, so I'm wondering if this shall be nicely visible...

Nice to know the seeing wasn't good strange as it might be to say it. Took my new 16in Lightbridge out into our new tiny back yard where its dark but with not much more than the zenith viewable. Really just to do a star test on the mirror than any observing. I can just about see polaris from the yard over the neighbours high wall but when I put a high power on it, it was imediatly apparent that the view was too mushy to do a star test to check for TDE under/over correction etc. Even stars at zenith were not pin sharp like I was used to in the Orion 12in. Then I realised that the CH boiler vents into the yard which doesn't help but now I know the seeing wasn't great regardless. I was starting to worry my mirror might be a lemon but at least now I can reserve judgement till conditions allow for a proper test which last night it seems wasn't.

One thing last nights short test/first light showed me is that I definately think I will need a paracorr though. Starfields in the F4.9 Orion XT12i were pleasing except the outer 20% in my 32mm. Even my 17mm in the F4.5 Lightbridge exhibited too much field curvature and too far in from the edge of the FOV.

But anyway, after your descriptions of M51 and M101 et al, I can't wait to bring this 16in scope to the next SDAS session!

He, he. Yeah, that 4 meter focal length gets you looking for a 31 Nagler pretty quick, doesn't it? Nice report. I think M51 is still my favorite target for that scope (although M13 is a real treat too).

(Have you gotten any solar observing done in the last 6 weeks or so? Even when it's reasonably clear, the horizon has been cloudy or hazy for me, and I haven't gotten a single view. Is this some micro-climatic effect of the Boyne, or is it just life at 54°N in the winter?)

Cheers,
-- Jeff.

I have actually. I got a 0.6A Daystar filter recently with a 75mm ERF. Only one prom worth noting so far from a few dyas ago. Very nice!! Must get a larger ERF and a lower power 1.25" eyepiece.

Michael.

A good session there Michael,
How much of the field of view diameter does M51 take up with the 31mm?