Looking down at the open RA motor housing. The motor drive gear is the left one; the little gray circles on it are the set screws.
After this 5-minute pause, I was back to alignment. I re-aligned, and also re-calibrated the autoguiding software PHD2, since I forgot to do that last week when I re-polar-aligned it. By 8:45 PM, I was off and imaging! Time to go hang out inside, have some wine, pet my cats, and watch some TV.
On the imaging docket was, with my ZWO ASI1600MM Pro and hydrogen alpha filter:
- Pacman Nebula
- Heart Nebula
- California Nebula
- NGC 2174 "Monkey Head" Nebula
- M31 Andromeda Galaxy
- M42 Orion Nebula
- Rosette Nebula
In the morning, I looked out a back window as I usually do to check that it had indeed returned to the home position -- and it had not! It was pointing down at the ground!
I was a little perplexed at how this could happen. However, it didn't take me long to figure it out -- the clutch had some loose. Over time, tightening the clutch advanced the position of the knob, and when the mount rotated, it was dragged across the dec motor housing, which loosened it back up.
Luckily, this was also easy to fix: you simply take out the Philips-head screw that holds the knob to the bolt, rotate it upward, and screw it back in. Done!
I looked through my data, and unfortunately it had only gotten through the Heart Nebula before it slipped. Dang. Oh well...