NGC 281

Continuing to explore technical nuances, it turns out the 585 is very finicky about calibration temperature, unlike the 533. A five-degree difference is no problem for the 533, but here it directly causes haze. Measured the backlash in the focuser and autofocuser connection; the backlash was 0.3 mm, which I compensated for programmatically in ASIAir, resulting in 88 EAF steps. It turns out that with enough skill, you can roughly gauge the backlash from the graph without needing cross measurements. Pulled out the 662 and IR Pass 685 filter prepared for the moon, installed the 200mm guide scope, and reduced the error to 0.6–1, even under humid conditions—infrared guiding really works. Checked all filters in the wheel by shooting flats; everything is sterile, not a speck of dust. I think I've now addressed all the technical aspects, and the small pixel of the 585 is finally performing as it should.