Note the slight blue marks at the top of the frame. These are artifacts from calibration of improper amp glow removal. Means that there's something not quite matching in the dark vs light. Probably a real temperature difference vs the EXIF temperature. Will try calibrating with a range.
This was calibrated with Maxim using a library of darks that have been recently captured -- within the beginning of the month. Pix Insight was used to color calibrate, histogram stretch, and curves applied to drive the background a little darker. No other processing used since this was a single image.