The mirror was overcooled and was ~5.5C colder than the low dome temperature at the start of the night. As a result, the DIQ was very poor for the first half of the night, and significantly worse than the seeing FWHM reported by the DIMM. The low dome temperature continued to rise through the night making it hard for the mirror to catch up. DIQ was decent (~1.1-1.3") between 0300-0500ut, but then low dome temp began to rise again. The low dome temp is not really keeping track of the ambient temperature, which raises the question of whether it is reporting the right value. Median value for the DIQ determined from all images taken was 1.4"
We had two cases of the dome occulting the beam: [1] at 04:08ut (during 678007); [2] at 08:57ut (during 678115)
| Total Times | Time Observed | Time Engineering | Time lost technical | Time lost weather | Time lost other | Total Program Time |
|---|---|---|---|---|---|---|
| 2017-09-15 | 10.0 | 0.0 | 0.0 | 0.0 | 0.0 | 10 |
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Beautiful clear night. No significant problems other than the poor DIQ, which was probably largely due to the over-cooled mirror. I realize it is hard to predict when the conditions are changing rapidly. Tomorrow night is predicted to be similar to tonight, so perhaps we can hold the mirror at its current temperature.