Old Business!

After catching up the other night with our last trip to Whitewater, I'm still need to catch up with old business.  It will be 2 weeks on Saturday that we had the "high fire" of the latest Giant Magellan Telescope (GMT) casting.  Along with the spinning oven with 20 tons of molten glass inside,  the Steward Observatory Mirror Lab had an open house for GMT and their partners.  Along with that we had both polishing machines going, using the stressed lap doing near-final polishing on the first GMT mirror, and also working on fine grinding of the M3 surface of the Large Synoptic Telescope (LSST). 

The "high fire" part of the casting, where the oven temperature reached 1165C, allowing the molten glass to run into the mold, went nearly flawlessly.  There were some minor electrical relay problems that will mostly be an issue during the annealing phase the next few months, if then.  And of course, the polishing operations have been making steady progress and was enjoyed by all the visitors.

For grins, I thought I'd set up a camera and tripod to catch GMT polishing with the visitors in the background.  I found a spot over our sink near the Large polishing Machine (LPM), and set it up to take a picture every 15 seconds, 240 per hour.  Between a write error and a dead battery, which each paused the sequence, I got just about 2100 pictures over 9 hours.  It covers the initial lap and mirror cleaning, pressing the lap for a short time before starting the flat removal stroke, while operators ran the machine, press arrived, then the visitors came in several waves of tours on the stairs in the background.  The picture above is the last one of the sequence, of me as I shut down the camera.

I then loaded all the frames into "Windows Live Movie Maker" and made an HD .MOV file and uploaded it onto Youtube.  Click on the link here to see it...  There are a lot of interesting effects to notice - of course the operators are moving something like 150X normal speed - I had lots of comments with the internal Steward distribution along the lines of "I wish they worked that fast all the time"!  Another thing of note is that the mirror is so aspheric (far from a spherical surface) is that you can see it's effect in the reflection as the mirror spins.

Anyway, a fun day - free t-shirts (and food!) for the staff, so about time I did a blog post!