It was looking grim. It snowed on Wednesday night and into Thursday. Bill Danchi and Rafael Millan-Gabet joined the observing team Thursday as Vanessa Bailey and Mickael headed down the mountain. The forecast for the weekend called for continued snow, with maybe a pause in the action Friday night.
Worried that we would be caught on the mountain due to the snow accumulation, we headed back to Tucson on Friday, with the option to carry out remote observing from Tucson. Surprisingly, it cleared down in the valley around sunset. Geno, (the telescope operator) kept the roof heaters going and cleared the snow off. Around 9 pm it started clearing on the mountain top, and we gathered in Tucson to begin the night.
The first step was to debug the stability of phasecam. The system appeared to be losing lock every time we tried to adjust which "fringe" the system locked on. It appeared to be due to some interaction between the tip feedback and the fringe hopping routine. We also found out that an attempt to limit the tip-tilt errors added in December seemed to be making the instability worse. We took additional data and refined gain parameters to have a reasonably stable phase loop. It would still break every other nod or so (every ~five minutes) but was usable. The data gathered should allow us to develop improved filtering of the phase-tip-tilt errors.
Surprisingly, as we completed this, the sky had cleared enough that we could gather decent quality 10 micron images. It was high humidity but clear. We set up on beta Leo and a calibrator and went to work. We gathered one SCI-CAL-SCI sequence before the rising humidity forced us to close around 5 am. The nulling sequences were taken at both 30 and 60 ms DIT (detector integration time). This will be compared to November's use of 15 ms for sensitivity and systematic errors to settle on an optimum DIT for HOSTS nulling sequences.
The remote observing worked surprisingly well, and may become more routine, if we can solve some network congestion issues.
The group's feeling by the end of the night: