Ok, so this turned out halfway good, IMHO, but as with any activity served to further point out the limitations in both my equipment and my technique. For your entertainment, the net of four nights' work, two of which actually contributed to the end result.
Night 1 was under a (literally) full Moon, just to see if I could actually image anything under those conditions, and to grab a "contingency image" in case the rest of the month's weather turned out to be bad. It worked, but the gradients caused by the Moon interacting with the light pollution and the atmospheric conditions were just a bit more than I could filter out. Interesting image, but I didn't end up using the data.
Night 2, two weeks later, was intended to be The Night. Ended up a total bust. This is where the issues with temperature-induced focus drift came to a head, colliding with massive (for this neck of the woods) dew. I have no dew protection other than the built-in shield, and when you're essentially looking straight up, the dew shield becomes a dew bucket... Not good. The results of several hours' images looked like you'd expect, out of focus and under water, being guided by someone with even less optical acuity. Additional mishaps included my first-ever attempt at a Meridian Flip, where the mighty AVX bashed the camera into the tripod leg as it went by, messing up the alignment. Nothing a new plate solve couldn't fix, and apparently no damage done, but annoying and a bit scary none the less. Note to self: manually move the delicate parts far out of the way with the hand controller BEFORE doing the post-meridian flip.
Night 3 was good, with acceptable image data, and I also captured some data related to the focus issue. See https://www.cloudyni...fects-on-focus/ for the focus topic.
Night 4 (last night) added more image data, along with some experimentation on PHD2's settings, none of which really helped. I tried getting a better RA balance, and switched from Predictive PEC to regular guiding, but neither tamed the scope. Either way, the excursions, primarily in RA, were sufficient to be visible in the shapes of the stars. Sorry 'bout that. Result is that I'm re-thinking the priority of a new camera (for Nebula season) vs a new mount (for better guiding). I might "cheat" and get a reducer first, making the imaging train a bit more numb to aiming errors, and increasing the FoV for the larger targets to come. It's also half the cost of a new mount... Focus was better, due to better weather and more frequent refocusing. Solution there is likely (hopefully) $13 worth of insulation. We'll see.
Weather for the rest of the week isn't going to be any better, so I'm calling it here with just over 2 hours of total integration.
Scope: Stellarvue SVA130EDT (130mm f/7), no reducer or flattener
Mount: Celestron AVX
Guider: ZWO 60mm f/4.6 guide scope with ASI174 camera.
Camera: Nikon D3200 unmodified; ISO 6400, acquisition via Intervalometer
Compute environment: Astroberry software on a 4GB Raspberry Pi-4B. CCDciel + ASTAP for plate solve, PHD2 guiding
255 x 30 seconds exposure (2hrs 8 min total)
20 darks, 20 flats, 20 dark-flats each of two nights
Stacked in DSS, processed in StarTools, cropped to 61% of original
Edited by TelescopeGreg, 26 May 2020 - 04:35 PM.