My objectives were to possibly shoot Jupiter early with the ASI178/Meade/G11, work on polar alignment with the ASI6200/TV/GM8 and possibly shoot a stars-only target, and finish up by shooting the Moon with the ASI178/Meade/G11.

The weather was warm (at first) to chilly (later). I put on a sweatshirt as it got cooler. Dew was not present at all and there as an occasional very light breeze. Seeing was about 5 of 10. It was an enjoyable evening to be out.

I went out to set up at about 1810 and was up and running with the Meade by 1845. I would have taken a look at Venus, but it was in the trees. I decided instead to try Jupiter with the new camera. I had to wait a few minutes for Jupiter to clear the trees, but was ready to get to work as soon as it did. As a result of working at prime and having accumulated experience with the flip mirror, I found Jupiter on the display as soon as I flipped the mirror up.

I shot it in first in full color with a tight ROI at normal exposure settings. I then shot a set with an ROI that covered Jupiter and the four Galilean moons that was highly over exposed, hoping to pick up some of the smaller moons for the first time. As I think about it this morning, I wish I had captured another run with even more exposure.

After coming in for dinner, I went out to work with polar alignment and tracking on TV/GM8. I was able to get up and running with no issues. I first polar aligned with PoleMaster, and found it to be about 15’ off (about 1/4 the distance between Polaris and NCP). After two adjustments (put Polaris in the circle, and put the red and green boxes on top of one another), I repeated the process two times, and at the end of each try Polaris was perfectly centered in the circle, and the boxes were one on top of the other. I accepted that result and moved on to PHD.

In PHD I slewed to meridian-equator and calibrated. My result about a 15 degree orthogonality error and I got a fairy decent graph. This was much better than last time, and I attribute the this to the backlash adjustment that I made a few days ago. I then let it guide for a few minutes and found about 3-4’ total RMS error. I then stepped into Guiding Assistant tool. It reported my polar alignment error at about 10’ (yes, definitely minutes), and I accepted the recommended parameter changes. I did not attempt to adjust polar alignment.

This might have been a moment of brilliance. It occurred to me that if calibration were done with guiding parameters worse than I have now, would the calibration be better with better parameters. I did another calibration and found the orthogonality error to be about 8 degrees. I let the guiding run for a few minutes and found total RMS error to be about 2.3”. I then went back to the Guiding Assistant tool and found the polar alignment error be reduced to 3’ even though I had not adjusted the alignment. It seems that doing a calibration with better guiding parameters made a difference. Thinking about it this morning, I am not sure that this makes sense.

So why not another round, I thought. I went back through the sequence again. Orthogonality was about 7 degrees, total RMS a little less than 2”, and the reported polar alignment error was less than 1”.

My conclusions from this exercise are that having better guiding parameters improves a lot of things, and a couple of iterations to get dialed in might not be a bad idea. Since the guiding parameters are saved, I would not need to iterate any further to get the same result that I did last night. One calibration would be enough. But maybe I could do a couple more iterations to get an even better result? Here’s a startling conclusion. The polar alignment error reported in the Guiding Assistant is dependent upon the calibration result, so I do not think that this is a reliable metric. I do not know if the PHD drift alignment is dependent upon the calibration result.

After three iterations, I decided to move on and see if I could image something. I was able to get NINA up and running without too much fuss. Still banging off rust here. Discipline, it turns out, was among the rust that didn’t get banged off. Much earlier in the evening I had decided that I would shoot a stars only target if I got this far, because anything with nebulosity doesn’t hold up well under a full moon. I saw that Triangulum Galaxy was well positioned for a couple of hours of imaging, so I went for it. That was a poor decision. I doubt that I will process this data.

After I had the TV/GM8 clicking away at M33, I powered up the Meade again to shoot the nearly full moon. Working at prime focus, I tried to cover the whole disk. We’ll see how that works out in processing.

The Moon - 2021-10-20 03:26 UTC - Crater Thales
Crater Thales

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