March 19th – Day 80 on Ice

Weather: Coldest day I’ve ever experienced, but beautiful weather. Slight breeze of a few mph, partly cloudy so that the Sun has something to cast it’s warm pink and yellow glow on. Temperature -80F, windchill -110F. The sun is now touching the horizon, elevation < .5deg.

Unfortunately the EHT observations have been canceled due to the COVID pandemic currently effecting the rest of the world. This means that we’ll be going right into SPT3G winter observing after sunset. It’s a shame, as I was really looking forward to doing something a little different than usual, but at least we don’t have to spend an hour putting up the optics, then 4 days testing the system, then 5 days running observations in a stressful sequence of observing-calibration-observing-calibration, etc. where we can’t even take 30s breaks in between.

I did however, spend a few hours this morning helping BICEP and BICEP Array take down their mirror and their calibrator source (the big pie-dish looking thing on top of DSL). It turns out that even in full ECW, -80F is pretty cold, and will sap all the heat out of your body in less than an hour.

Sunset is only 2 days away, and the sun is just now touching the horizon. The colors in the sky are similar to sunsets back home, with pinks and blues and yellows and oranges. It seems like a brisk early morning sunrise, more so than a sunset, but soon enough we will have 6 months of darkness. Excitement is mounting for stars, and auroras. Fingers crossed that the weather holds up and the sunset isn’t obscured by overcast grey, and blowing snow!

Here is a short ~1hr timelapse of the low sun, partially obscured by clouds, from last night.