Home of MagAO and MagAO-X.
As originally reported on the Steward Observatory website, and archived here for posterity:
On Jan 17, NBA Hall of Famer, one of “50 Greatest Players in NBA History,” and iconic Deadhead Bill Walton came to town to be the color commentator for the UA-Oregon men’s basketball game. Whenever Walton is a commentator ESPN has a 2-minute feature called “Walton’s World.” In this episode, Bill visited the MagAO-X lab at Steward!
On September 17, 2018, we got our first look at the MagAO-X vAPP (that’s “vector apodizing phase plate”) coronagraph optic. Kelsey Miller had been working with the phase pattern for a long time, but there’s something special about holding it with your own hands. Or, at any rate, watching the P.I. hold it with his own hands.
“Without phasing, there’s no real reason to build the GMT.”
-Andrew Szentgyorgyi
The biggest optical/infrared telescope in world will be the Giant Magellan Telescope, which will be built on a nearby mountain peak within sight of the Clay and Baade telescopes at Las Campanas. The telescope will have 7 primary mirror segments and 7 adaptive secondary mirrors, similar to the Magellan AO system.
If we could build any optic we wanted for the primary of the GMT, we would probably build a monolithic 30 meter diameter (or larger) mirror made of a single piece of glass, with a thin face sheet and a honeycomb lightweight structure on back. However, at the moment, the largest mirrors in the world are built in the Steward Observatory Mirror lab under the bleachers of the football stadium at the University of Arizona and are limited to a diameter of 8.4 meters. Depending on who you ask, this 8.4 meter limit comes from either the distance between the columns underneath the stadium bleachers, or the size of an underpass on the highway leading from Tucson.
Because of this limit, the GMT is designed to take 7 of the largest mirrors that can be made and combine them to form one giant 25.5 meter primary. For this to be possible, the seven 8.4 meter segments must be “phased” to a fraction of a wavelength. That is to say, they must be aligned to each other so that they act as if they are one large continuous mirror.
To achieve the phasing of the GMT segments using off-axis natural guide stars, SAO and our collaborators at GMTO and Flat Wavefronts have designed a sensor that creates dispersed interference fringes using subapertures spanning the 12 segment boundaries. Phase shifts across the segment boundaries manifest themselves as tilts in the fringes.
To test this sensor technology, SAO has built a phasing prototype that simulates 6 of the GMT segment boundaries working in conjunction with the Magellan AO system. Our three nights at the end of the MagAO run turned out to be a success.
We obtained phasing data both on-axis and off-axis, with AO on and off, and at two different wavelength bands (I and J). This data, and data that we gather during another run possibly in February, will inform the design of the GMT phasing sensor, scheduled for first light in the next decade.
Lastly, a “song of the run:” Phazing, by Dirty South:
https://www.youtube.com/watch?v=031hzipvnTY
President Michelle Bachelet addressing those celebrating the groundbreaking event for the GMT on the windy evening of November 11th.
On November 11th, I had the great pleasure of attending the Groundbreaking Ceremony for the GMT. It was a very windy, cold, but happy occasion. I’ll be posting a more complete update in the next 24 hours, including hopefully some of the photos that I was able to take during the celebrations. The event was well attended, including wise and often humorous remarks by the ambassadors to Chile from Australia, South Korea, and the United States. The President of the Republic of Chile, Michelle Bachelet, was the keynote speaker. Everyone working to build GMTO (the GMTO staff, the many people from all of the partners involved, including the talented women and men of Steward Observatory and the Richard F. Caris Mirror Lab) should be very pleased to see the project reach this milestone.
Fortunately for the MAGAO team, the more than 150 people that were visiting the mountain yesterday have now left, leaving hopefully enough room for you to work and sleep during your upcoming long observing block!