Ags

Looks battle-scarred from its battles with faint nebulae 🙂 It's not all bad, I would be happy to have that gunk on the corrector plate which you can wipe down with cleaning fluid, rather than on the fragile mirror behind it!

My risotto is always nice! I went out later (after the Dragon launch) and spent some time observing the Moon with various eyepieces. The view was excellent - even holding up well at 280x magnification.

I was thinking that those two astronauts must have felt good sitting in a spacecraft that looked like a real spaceship (those big blue screens, the futuristic lines) and they were dressed to kill in those stylish space suits!

It's worth thinking about: the cheapest commercial launch system in the world is also rated for human spaceflight, and it is partially reusable. Falcon 9 is really one of the most remarkable rockets in the history of the space age.

We were warming up leftover risotto for dinner when I noticed the moon in the blue sky. I thought I had 10 minutes to take a few quick pictures. I grabbed the AZ-GTi and C6 and plopped it outside, quickly screwed on a Wratten 28 onto the ASI 178 MM to cut out the sky glow, hooked up the laptop, did a one star align and was ready in 4 minutes, mostly waiting for Sharpcap to start up. I forgot gain was 310 due to my DSO photography so the view was overexposed to say the least. Quickly adjusted exposures down from 400 ms to 3 ms, and shot 3 sequences along the terminator.

I think RK stands for Reverse Kellner.

What came before the Big Bang? The Long Tick Tick Tick...

I am working on this M57 with my AZ GTi. Gathered 30 minutes of data but only stacked 50% of it so there's still a lot of noise... :

M13 is not hard to observe, it looks good in all telescopes. I enjoyed the views of it for many years with a telescope with half the light gathering power of yours and even at that aperture (4 inches) could resolve some of the stars in M13 with averted vision. At 6 inches the stars are still quite faint but I don't need to use averted vision any more. I think what John and I were trying to say is you can get a good view of M13 (and indeed many other objects) with your telescope, but you need to spend a little time observing it to see the details the telescope can reveal. Another target worth looking at right now is the Ring Nebula in Lyra, and pay a visit to the colorful double star Albireo (the head of the swan in Cygnus).

I have a C6 (same aperture as yours) and used to own a 6 inch newtonian. At low magnification you can't pick out the faint stars against the general glow of the cluster and the light pollution. As you increase the magnification, the background glow gets stretched out by the magnification and gets dimmer, but the stars remain points and don't dim much if at all. So more magnification helps resolve the stars - but too much magnification loses the fuzzy structure of the cluster, so it's a balance. I get best results at 100 to 150 magnification with my 6 inch aperture. It's also worth noting you don't just need magnification, you need good magnification to tease out these delicate stars. So get collimation right, and make sure your barlow and eyepiece are up to the task.

There is no diagonal - the back of the scope is one solid unrotatable flip-mirror unit.

Your mobile setup's battery weighs three times more than my whole setup (AA batteries included)!

Normally (unless you are doing eyepiece projection) you attach the DSLR camera directly to the telescope (with no eyepiece) so that the telescope is simply a giant camera lens. This is the normal technique for astrophotography and is called "prime focus".

Just come in from another night of looking at doubles with the C6 with reducer. Again struck by the Mak-like star images I see, notwithstanding a very teeny bit of miscollimation that I must sort out sometime. I used my Explore Scientific 24/68 and 6.7/82 for all observations. Polaris was a lovely sight with perfect diffraction rings and a faint but clear companion. The Double Double was split into all four components despite still being a bit low. Albireo was colorful and best in the 24/68 with a slight touch of artistic defocus to bring out the colors. Sadly 61 Cygni was hiding behind my grape vine. Paid another visit to M13 and it does seem better resolved at 140 magnification with the corrector than it did at 150x without corrector. All in all, I would have given the C6 six out of ten for visual use before corrector, but now I would award it eight or nine.

Firstly found that normalize stack is not available for stacks using surface stabilization. But the FITS format does solve the issue - especially as I now see GIMP can open FITS directly. I did a quick stack and stretched the data to the extremes, but at no point the the histogram turn into a comb, so my problem is solved!

It's always night in space 😃

I think maybe my problem is i am not checking "mormalize stack" so perhaps the floating point values gt collapsed back to the same integer scale. I will try repeat the above image with "normalize stack" set to 75%. BTW, there is definitely no 32-bit option or "scientific stack" option in AS!3. I assume it just uses 32 bit precision all the time?

Did I miss another setting in AS!3? I don't seem to be able to sum, I can only increase SNR.

Don't blame the eyepiece, it was made for an age of long refractors. Get a cheap F13 four inch mak for it and enjoy the views 🙂

My signal is skimming the bottom of the histogram - if a pixel has a value of 5 or 6 in individual stacks, then after combining them I am still only left with 5 or 6. But if I increase the gain so the same signal gives a pixel value of 10 or 12, then after combining all the sequences I should have 10, 11, or 12, more closely reflecting the average of the sequences?

I am not able to get down to 100 ms frames. I am looking at an F4 reducer lens suggested on another thread by @vlaiv, which would get me closer the 10 Hz frontier. https://starizona.com/store/night-owl-4x-sct-reducer-corrector I stacked this image with a low frame rejection rate (80% of frames accepted into the stack), so I wonder if I reduced that to 50% or less I would get more detail in the core and tighter stars in general. The trouble is noise would go up... Another thought is to increase gain from from 310 to 360 on my ASI 178 - the theory is this will spread the weak signal so I will end up with a richer spread of levels after stacking.

Lots of mentions of various 25 mm Plossls. My 25 mm Celestron E-Lux plossl is the one eyepiece I really regret selling.

Just to write a happy ending to this thread, I got darks working, and also found that lucky imaging / lucky tracking works much better at F6.3 than at F10!

Here is a new version reprocessed from scratch without using the AS!3 banding removal feature.

The wider fields and ability to reach larger exit pupils are useful of course, but I want to emphasize I am seeing significant benefit at high mags too. Performance on doubles has been transformed by the reducer. Another consideration is weight - I don't want to be using enormous eyepieces or mixing barrel sizes.