Many thanks to scadvice, George, Norme, Wouter, Kevin, Steve, James, Glenn, and Darryl for all the nice comments. They are certainly much appreciated. I realized that until last weekend, I hadn't even set up my C9.25 scope since before Christmas! A mix of poor weather (at least by San Diego standards!), clouds, fog, rain, and bad seeing even when clear have been responsible for this. It was good to get it back out. I haven't been in any rush to attempt planets yet, since last year I really didn't get anything worthwhile on Jupiter until May, with optimal results occurring in June and July for both Jupiter and Saturn. The problem with early morning imaging is that I often get overcast skies that roll in around 4am, so I'm just playing the waiting game with Jupiter and Saturn for a bit. The waxing gibbous Moon near First Quarter is optimally placed right now for me, although I missed it last month due to clouds and horrendous seeing. This month was a bit better.
I will respond to a few specific comments and questions below:
Hyginus is great as well. I've focused on Hyginus before, but seeing it in your wider context makes it much more obvious it is different from other lunar craters.
Indeed, George. Hyginus is different in that it was not caused by an impact event, but is rather thought to be volcanic in origin.
Those are excellent results Tom! Even with the seeing at a Pickering of 4 to 5, do you feel that the various level winds were pretty unidirectional? Was your relative quality scale fairly uniform and were you able to stack a good percentage of images? I am sure the 70 degree declination helped!
I don't image with filters, so I casually read about their use, but if I remember correctly your use of a green filter must also indicate some fairly decent seeing.
Steve, I can't say much about the winds, other than there was a fairly significant jet stream but it was moving within 90 degrees of the same direction as surface winds. Mostly this outcome was just a luck of the draw thing. I imaged on Friday, Saturday, and Sunday nights last week, and Saturday had the best seeing of the three. The moments of "5" on the Pickering scale (for whatever that's worth) improved the outcome, whereas the other nights looked more like a steady "4". Still not bad, but the scale is fairly arbitrary, not linear, and the aperture used to gauge the scale definitely affects the quality of the outcome. Very decent imaging can be done at a "4" with larger scopes (despite being listed as "poor"), and very excellent images can be obtained at level "5", despite this being listed as "fair". I've only occasionally encountered something that I would call a level "6" or "7" with my 9.25 inch scope. But once you get to levels "3" and below, that starts to turn into the garbage zone for the Moon, especially with wide field imaging on the ASI183 where you can't run fast frame rates.
I took a screen grab from AS!3 after processing a few of my files. Here's an example below. As you can see, the seeing was very consistent. This graph doesn't mean "good", but simply consistent. Although it turns out that really terrible seeing is usually also chaotic, and so you don't get a graph like this unless things are at least decent. The other takeaway here is that if you add up all the times, you see that this file took 4 hours to process in AS!3.
For the two panels spanning the terminator, I collected 4000 frames and stacked 1000. For the two panels covering the limb, I only collected 1000 frames (due to file size space limitations) and used a 500 frame stack in the final result. I've found that when imaging the Moon, you can get very nice results stacking as few as 100-250 frames on the sunlit portion of the Moon, but the advantage of stacking more frames comes in the form of SNR improvements in the shadowed regions along the terminator. Extra frames stacked don't necessarily help improve resolution or detail, but do allow you to increase the exposure in post without introducing as much noise along the terminator, which serves to increase the amount of perceptible detail. For the more evenly illuminated portions of the Moon, you can get away with fewer frames collected and stacked. If a stack of 250 frames (assuming exposure settings were good) doesn't yield good detail on an evenly illuminated portion of the Moon, then the seeing wasn't good enough to make it worthwhile.
With regards to the filter, green is usually associated with good seeing, but my Baader green filter has become my standard filter. I tend to use this by default now. I feel like the restricted bandpass helps resolution, even if seeing is only "fair", whereas a long pass filter allows many more wavelengths to pass though, potentially reducing resolution. In general, if conditions don't look like they are worth using the green filter, then I won't even image with the C9.25 and I'll just use my 6 inch Newtonian. Although even here, with the smaller aperture, I still would be inclined to use the green filter. The difference in results in likely marginal though. For an interesting comparison, take a look back at this post I made over a year ago in March 2018 using the 610nm pass filter.
That lunar phase is almost identical to the one in this post, varying by less than 2 degrees of longitude of the terminator, which amounts to less than the width of Copernicus, as you can see by comparing the images. The detail in these images is nearly identical, and in fact any differences are probably within the normal variation of processing. However, I feel like there may be slightly more fine detail in my more recent image (resolution, not contrast....my image from last year has slightly more contrast in some regions, due to processing variations), although you really have to pixel peep, and even then, it's arguable. I seem to recall the seeing from last year's image with the 610nm was better than the seeing I had last weekend, but that's also hard to say definitively. Basically, both filters produce very nice images.
This lunar phase and the following day probably have more more opportunities for good images than any other time on the moon. The last quarter moon and the waning gibbous really don't have anything to compare (in number).
James, I agree this is a great phase to image, with many of the most popular features visible. I also like the waning gibbous Moon at about 1-2 days before Last Quarter, but in that case the window is closing on many of the popular targets, whereas in this case the window is just opening. Also, waning gibbous Moons require more dedication, as often the best time to image is 4am. The other thing I like about the waxing gibbous Moon just after First Quarter is that you get several days worth of good imaging near the poles, since the terminator moves less in absolute distance the farther you get from the lunar equator. Whereas you may only have one day of optimal lighting on Ptolemaeus, you usually get several good days on Clavius to the south, and Plato to the north.
Once in a long while an image shows up here that truly astounds, and this is one of them. Celestron could not issue a better advertisement for an EdgeHD 9.25.
Thanks for the kind words, Glenn. If Celestron wants to help me fund an upgrade to a C14 Edge, I would be happy to provide them with some promotional material! In all seriousness though, I have been very happy with the C9.25 Edge. On a dozen or so occasions per year, I am able to push the limits of this scope, and it really does perform quite excellently. In better seeing, I often play around with 1.5x drizzle versions of lunar images with my ASI183mm, and I also have a Siebert 1.3x barlow to fully maximize the potential of the 2.4um pixels, but to be honest, all of those variations are just tiny (almost imperceptible) improvements over the images at f/10, such as the one posted here. To really achieve a meaningful improvement in resolution, I would need to increase my aperture. I have often said in other posts that most people vastly underestimate the resolution potential of their scopes, due to a combination of seeing limitations, coupled with user-controlled aspects such as collimation, thermal equilibrium, focus, capture and processing parameters. But on the Moon in particular, the C9.25 Edge is a tremendous performer. An image such as this one only requires four panels to cover the entire Moon, and the less panels you have to capture, the better.
Thanks Darryl. The five thumbs up rating is certainly appreciated, and I would definitely enjoy seeing a lunar image or two from you! I know you posted one a few weeks back in another thread. If you ever had an entire post dedicated to lunar images, I think some people around here would be stunned!