GMT: The 7th segment is in the oven!

This past weekend, the MagAO-X team got to take part in a historic event, the casting of the 7th and final GMT segment! The Giant Magellan Telescope is made up of 7th petal-like segments, and the Mirror Lab—a facility on the University of Arizona campus—is the only place in the world that can make them. These 8.4-meter segments have been in production for decades now, and this weekend the final one has started the 6 month journey of melting glass in the 5-rpm rotating furnace, until it cools to a room-temperature parabola. On Saturday the furnace reached its peak temperature, and from there it begins to cool. Interested parties, donors, and investors gathered to celebrate this milestone for the GMT.

On Friday and Saturday, some of the MagAO-X team helped the mirror lab staff give tours. Jialin and I have been training as tour guides for the last few months, Jared’s been doing it since his grad days, and Maggie was there as a GMagAO-X expert. First stop on the tour is the main attraction, the Furnace Room!

The GMT Segment melting in the spinning furnace.

The furnace is actually two levels, with the lower level focused on controls and system monitoring. You can see the large holder where the mirror segment will be hosed out.

Second view of the spinning furnace.
Ohara glass, what goes into the furnace.

The furnace room was hot! You could feel the difference in the oven heating just between Friday and its peak on Saturday. The next room over, where mirrors are ground and polished, is noticeably cooler than the first room. It’s kept at a constant temperature so that there’s no expansion of the glass as it’s brought to nanometers of the specified shape.

Polishing a 6.5m mirror.

Past the polishing room is the integration room, where GMT mirrors are stored in between their different stages of production. One of them, covered in blue, is actually on it’s way to being stored off site! Others are upside down, as they need their actuated backs attached, and so on. This set up is affectionately called the “CD Switcher”.

CD switcher with 3 different GMT segments.
A mirror almost ready to ship!

The three of us were stationed at the end of the tour in the integration room. This isn’t usually a stop on public tours, but it was opened up for the festivities. We got the honor of explaining how excited we are to do the science that the Giant Magellan telescope is built to do!

Prepping the talks and setting up the posters.

In the marching order, I was first! I introduced what MagAO-X is (an extreme AO instrument directly imaging exoplanets on the Magellan Clay telescope) and explained some of the basics of AO.

Me showing MagAO-X in action.

Next was Jialin, talking about the exciting science we get to do with MagAO-X, and the motivation for wanting to make our pretty pictures even prettier.

Jialin explaining what exactly is so cool about H-alpha acreating proto-planets.

Maggie then got to talk about the plans for GMagAO-X! Her work on HCAT, where we’ve done phasing development in lab, is a huge step forward in the feasibility of the project. She got to show the visitors what a GMT pupil would look like.

Maggie explaining the phasing problem in the next generation of ELTs

Finally, Jared got to talk about his favorite planet. Not caught in action, but by the end of his talk, everyone in the audience was thoroughly convinced of the impact that GMagAO-X will make on the exoplanets we love.

Jared prepping his slides, finding the best fake image of Prox-Cen B.

Hanging out with giant mirrors and speaking on the projects we work on was a huge honor! We hope to get to be back when they pull the mirror out of the furnace in March, and for plenty of tours in between.

The team after all the mirror lab tour madness.

Bonus Video:

The team talking about the GMT in an interview recently! This was shown to some of the guests this weekend, and will be around Steward for a while, I’m sure.