June 14, 2026.
It was a long wait but finally everything aligned: personal availability, cloudless sky, hardware readiness. The location was the M.A.S.'s Eagle Lake facility. The goal was to see if everything worked well. I think it mostly did, but there were several distinct glitches.
First was PoleMaster. Normally PM delivers amazingly accurate polar alignment quickly and easily. When I compare first and last frames of a full imaging session it's almost always difficult to see any field rotation due to misalignment. This night, at least for a while, it misbehaved.
Because of my laptop's problems (see previous post) I had to reinstall PM, and I used the current version, an update from what I had been using. This new version seemed not to want to run for me. Four times it failed to generate the celestial pole marker needed for adjusting the mount's polar axis. I finally got it working by using very large calibration rotations. This never happened with the older version, so I've stepped back to that.
Once the mount was polar aligned, it was time to calibrate PHD2. I used the Calibration Wizard; it slewed the scope to its preferred orientation and did its thing. At calibration conclusion it reported the quality of the calibration was poor and that it should be repeated after changing some of the settings. This is something I'll have to research for next time.
As it turned out, the stars in all 53 light frames were nice and round, so PHD2 seemed to be working fine. PHD2 reported sub-pixel guiding error. Maybe with the focal length I was using (about 387 mm) it's not a discernable problem. It's worth noting that during the 2+ hours of imaging there should have been approximately 8 dithers and 5 autofocuses. PHD2 behaved perfectly across all of those.
The next problem was an odd behavior of NINA's manual rotator. It was giving wildly varying recommended rotations, as if it were making random guesses. Plate solving was giving correct results and the mount had slewed and centered the target without any issues. After a few tries I simply did manual rotations until it looked about right and finished with a final slew and center. This was fine for a simple single-session image, but won't do for collecting multi-session data or data for a mosaic. I have no idea what might have caused this problem.
All those things were eventually overcome, but I still managed to mess up the image!
At about 1:20 AM a band of high clouds came through and I decided that rather than wait for it to clear again, I would call it a night. Then in my impatience I decided to defer shooting the flats until the next day. Big Mistake! There was a largish dust mote on the flats that ended up being misaligned when I finally shot the flats. My finished image has a nice dark crescent on one side of that mote, and a light crescent on the other.
It's not much of a loss: I knew going into the evening that the image was not going to be a "keeper." I was imaging into the sky glow over Minneapolis and 106 minutes of total exposure was inadequate for the object (Sharpless 129).
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| A so-so image ruined by awful flatting; note the lovely donut just below center |
On the plus side, I did learn how to process one shot color data in PixInsight. And now I have a NINA sequence for shooting flats so I won't have an excuse to skip that.
The July new moon less than a month away!
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