Yesterday I finally got the chance to climb up on the telescope, to see the mirror up close. Ostensibly I went up there to brush some snow off before we start doing observing tests, but really I just wanted to see.
Yep, that’s me in the red coat standing right in front of the 10-meter diameter SPT primary mirror. The mirror is made of many small panels, each about 3feet or so “square”. Each panel was machined from aluminum, using a very precise milling machine (ie, cut with a sharp tool). All the panel surfaces are aligned to within about 40 microns of the desired surface; that’s about the width of a human hair.
Here’s some video of the route up there, filmed by Abby standing on the roof of the “Dark Sector Lab” building right next to the SPT.
Video: climbing up onto SPT
Here’s another video, which I took while up there:
Video: Up On the Telescope