On the night of Oct 11/12, 2022, I attempted to observe an occultation of a background star by the asteroid (817) Annika. Our observatory lay inside the predicted shadow path, which was good; but the star and asteroid were both faint, which was bad. Worst of all, the event was predicted to take place when the target was just 6 degrees above the south-western horizon.
Even though this seemed like a longshot, I decided to try. I arrived more than two hours early so that I would have time to set up the equipment. There were no problems: I was able to acquire a GPS lock and focus the camera. I pointed to the location of the asteroid -- very low in the southwest, but still above the trees. Still an hour to go. I took some test images, just to check that all was working. Yes, it was. Good.
So, I waited. And waited. The field drifted lower and lower in the sky. With 20 minutes to go before the occultation, the field slipped behind some trees. Arrgh!
Better luck next time.
Addendum: When I reviewed the "practice" images I'd taken, and tried to match them up to the region of the sky in which the event was to take place, I discovered a problem: my images were NOT in the correct location! Instead, my images were some tens of arcminutes to the west of the proper location. What happened?
The problem was two-fold:
In the future, I should always make finding charts in advance, using Aladin. There are several built-in checks that will catch an error of this sort if I follow that method. But I should also modify Stellarium on the dome computer so that it is set to show the grid of coordinates for J2000 as well.