Integrated Flux Nebula Mini-Test Result

 Let's get right to the image:

Polaris IFN luminance trial

The total exposure was a scant 1.8 hours (72 x 90 s). NINA ran the acquisition and PixInsight handled the processing. Flat frames were used. The nonlinear stretch was the PI Screen Transfer function and no attempt was made to enhance contrast beyond what it provided.

This is so far beyond my expectations that I don't know what to write. It was a not-very-dark site, the moon was at first quarter high in the ecliptic between Cancer and Leo, and there was a thin layer of smoke aloft. I really didn't expect to get much if any nebulosity in the image. But there it is.

The night's goal was to fully test the imaging setup and perhaps answer a few questions:

• Would go-to compose the image reliably? I started it once, collected a dozen frames, shut it all down, parked the scope and did the entire startup again. Plate solving shows the center changed by 67.5 seconds in RA and 7 seconds in Dec. Translating the RA difference to arcseconds at the equator, it's actually more like 27 arc seconds. That's total shift of about 28 arcseconds. The difference in image axis rotation is also tiny, about 0.11 degrees. So the answer is Yes, go-to works very well!
• Would guiding work so close to the pole? I had made some changes in PHD2--activating multi-star guiding and predictive PEC, and using the calibration assistant to make sure that was done optimally. Through the evening it collected 72 light frames, and only one had to be rejected (when PHD2 timed out after a dither). Tracking was next to perfect. I'm nor sure the ASI 2600 benefits much from dithering, so I'll disable it.
• Some people have indicated issues with field rotation when guiding near a celestial pole. I saw no sign of that. Possibly the excellent polar alignment from PoleMaster should get credit for this.

I do like the composition of the image, with Polaris shifted off center northward and looking as if it's shining light down onto the nebulosity. It's nice to see that the offset doesn't produce any significant internal reflection.

There are issues with this image, though. Although ASTAP reports moderate tilt I don't see any evidence of it. (Maybe it's some sort of algorithmic issue?) There are a lot of vertical bands in this that snuck in during the processing. I'll have to find a way to make sure to avoid them. [EDIT 12 May: see the reprocessed image here.]

PHD2 was doing something that seemed odd. Every now and then it would make a too-large declination adjustment and then follow that with smaller corrections. This may also have been my fault as I had the wrong guide scope focal length entered. This has been corrected, so I'll see if that takes care of the issue. 

Tonight I'll be out again to test my RGB acquisition scheme. Basically, I'll try the good old 3:1:1:1 channel ratio, meaning 24 frames for each color channel. How will the colors turn out?