These look really good, particularly below 4000A where i had trouble getting a perfect fit. What reference star did you use to calculate the instrument response ? Did you use the same one for all the targets?
I’ll check but I think it was HD87737 (another A class). It was a fair distance away if memory serves but roughly the same airmass. I used it for HD112413 and then (having got a good result) used that as a standard for the other two.
I have also been tinkering with a Relco bulb for better blue end calibration, mount backlash settings and PHD hysteresis to improve tracking. Most of the time it’s one step forward, two back, but I’m slowly making progress.
Not enough nights to observe and tinker at the same time.