Problem(s) Encountered:

I heard a slightly disconcerting noise when slewing to a target. I quickly looked around the dome mid-slew to make sure nothing serious had happened/was about to happen, but didn't see anything. Then as I was closing up I found a bolt lying on the green platform. I am not sure what that is from. Didn't ultimately experience any issues.

Solution:

The bolt was a sheared bolt from the RA drive roller preload.  Same as we’ve experienced a few times recently.  Reseated the roller and replaced all 4 (grade 8) bolts.  Should be good to go.