Despite it still being gloomy & overcast by lunch time, the sky cleared up beautifully through the afternoon & straight after dinner we came up to start aligning the primary mirror.
The bizarre weather from yesterday was safely behind us & we settled in for a long night's observing!
The Apogee camera has to be moved around a 3x3 grid to image the entire focal plane of the telescope - shown below is one of the nine images from such a set. The seeing wasn't ideal for much of the night, but encouraging images were obtained during intervals when the conditions improved.
However, our excitement was tempered by significant IQ variability on a timescale of a couple of seconds which we don't yet understand. The most likely source of this instability is the auto-collimator &/or the interferometer - two instruments mounted adjacent to the SAC on the NRS to control its attitude (tip/tilt) & focus (Z) with respect to the primary mirror. These pieces of equipment will undergo extensive testing over the next few days...