ENR CTIO Blanco 4-m 2019-05-21

Near the start of the night we had difficulty acquiring a target with cosmos such that the offsets wouldn't converge on the slit. After the first few yours, the acquistion offsets began converging better. Also, small offsets (1") would require quite a bit of time (few to several minutes) to re-acquire the guide star, which seemed longer than expected for such small movements. Near the end of the night, we found that the telescope focus was about 200 units lower than the value selected near the start of the night. It's unclear to me how/why it changed. When we tried setting it at the value from the start of the night (14300), the value wouldn't go above 13900. The night assistant eventually was able to get the focus to change properly.