I took this photo inside the dome of the Hale Telescope earlier today.
What is it? It is the reason why Electronicers have to wear gloves. What is an electronicer? It is the Palomar name for those who work with electronics, specifically electronic instruments that are mounted on our telescopes.
The photos above show a frosty valve that has a temperature cold enough to cause frostbite - hence the need to wear gloves.
If we take a slightly wider view you can see what it connects to:
It controls the feed from a tank of liquid nitrogen. The liquid nitrogen is used to cool instruments, such as the one on the right-hand side of the photo - the Hale Telescope's Wide-field Infrared Camera (WIRC). Unlike digital cameras used at home or in your phone, our cameras need to be cooled. Liquid nitrogen, which boils at a temperature of 321 degrees below zero °F is actually a bit too cold. So inside the camera we heat things a bit to bring the electronics to the optimal temperature for this camera, WIRC.
By the way, WIRC was the instrument used to take the image for last week's Astrophoto Friday image. and it goes back into service at prime focus on Wednesday night.