MMT Observatory
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mmtobservatory.bsky.social
MMT Observatory
@mmtobservatory.bsky.social
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The MMT Observatory is a 6.5-meter telescope at the summit of Mt. Hopkins, Arizona. The MMT is operated by U. of Arizona and Smithsonian Observatory under a permit from the US Forest Service. Any questions about what we do, just ask! https://www.mmto.org/
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mmtobservatory.bsky.social
The three week long “summer shutdown” at the MMT began last week. We spend the time working on annual preventive maintenance and engineering activities that can’t be done during normal operations. This year, that includes listening to the natural vibrations of the telescope (so we can suppress them)
Engineers stand next to the telescope with headphones. They are listening to a recording of the telescope’s natural vibrations and the motors.
July 29, 2025 at 6:08 PM
mmtobservatory.bsky.social
We see a lot of wildlife on Mount Hopkins, including snakes. But they're not usually hanging out on the door handles. This is a harmless mountain kingsnake.

Photo by J. Di Miceli
July 19, 2025 at 2:16 AM
mmtobservatory.bsky.social
On Sunday, May 18th, the sun set directly behind Kitt Peak as seen from the summit of Mount Hopkins. 🔭

Photo by Dallan Porter
The sun setting behind Kitt Peak. A number of observatory buildings can be seen in the foreground, silhouetted by the sun.
May 23, 2025 at 7:10 PM
mmtobservatory.bsky.social
Sometimes our staff take photos from a slightly different perspective. 🔭

Photo by K. Salmas
Looking through the chamber over the MMT telescope towards the south.
May 21, 2025 at 3:34 AM
mmtobservatory.bsky.social
Our 6.5m primary mirror got a much-needed contact wash a few weeks ago! This process is done twice a year, and helps maintain the reflectivity of the aluminum coating. #astronomy 🔭
The primary mirror is sprayed with water to start dislodging dust and foreign particles while the day crew prepares the mops. Cotton mops are dabbed on the surface of the mirror to wash it. The mirror is covered in soap and water. The mirror is dried with long air wands to prevent streaking. Someone stands in the central hole to soak up excess water with non-scratch material.
May 9, 2025 at 12:22 PM
mmtobservatory.bsky.social
Exciting night! The MMT, with the infrared MMIRS instrument, observed Uranus occult a star tonight! It was cool to see the rings and then the planet make the star (mostly) disappear. 🔭 #astronomy
Scientists watch one of Uranus’ rings occult a star Scientists observe Uranus starting to occult a star Scientists observe as Uranus moves past a star and the star’s light reappears
April 8, 2025 at 4:58 AM
mmtobservatory.bsky.social
A peaceful morning on Mt Hopkins 🔭 #astronomy
Grey-blue sky behind the summit of Mt Hopkins. The telescope and another building can be seen on top of the mountain.
March 20, 2025 at 1:22 AM
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We spent today at the #tucsonfestivalofbooks sharing our passion for science and demonstrating how we use masks to take spectra of multiple targets at once. We will be back again tomorrow!
Booth at the Tucson Festival of Book. There are a variety of posters and books on display
March 16, 2025 at 12:24 AM
mmtobservatory.bsky.social
Weather brings mountains down! A rockslide on Mount Hopkins road on Sunday, March 9th. There was a snowstorm on Friday, March 7th. Some of the snow melted during the day on Saturday and seeped into cracks in the rocks.That water froze on Saturday night and literally broke the rocks apart!
A rock slide is blocking the road up Mt Hopkins.
March 15, 2025 at 1:52 AM
mmtobservatory.bsky.social
Looking south from the fourth floor at sunset

Photo by K. Salmas

#astronomy 🔭
The MMT telescope as seen from the fourth floor of the chamber. Parts of the secondary support structure and the chamber wall can been seen reflected in the mirror. Mountains and a yellow/orange sky can be seen through the open chamber doors.
January 11, 2025 at 10:34 AM
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It’s not just astronomers who live on Mt Hopkins! A family of coatimundis were caught on camera crossing the road earlier this year.
Photos by A. Gerl
A family of coatimundis cross the road. A baby can be seen out in front Big step for a baby coatimundi. Its front leg is straight out and its tail is in the air.
December 19, 2024 at 9:35 AM
mmtobservatory.bsky.social
Getting ready for another night of observing. With 12 hours of useable dark time, these are some of the longest shifts for our night staff

#astronomy 🔭
The MMT telescope is open and pointed at a dark blue sky Orange sunset over distant mountains
December 2, 2024 at 12:58 AM
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A few weeks ago one of our operators captured comet C/2023 A3 (Tsuchinshan–ATLAS) from the summit 🔭

Photo by B. Pinault
Comet C/2023 A3 (Tsuchinshan–ATLAS) is seen against a dark blue background with a slight orange sunset glow below. The MMT Telescope building can be seen in the foreground.
November 25, 2024 at 8:26 PM
mmtobservatory.bsky.social
MMT Observatory staff gather in the chamber in front of the telescope for the annual staff meeting and picture.
Observatory staff people below the structure of the MMT telescope An MMT scientist looking at the reflections in the 6.5 meter telescope mirror
November 22, 2024 at 3:36 AM
mmtobservatory.bsky.social
Welcome to the official MMT Observatory Bluesky account! We are a 6.5-meter telescope located on Mt Hopkins, just south of Tucson, AZ.

Photo by R. Howie
November 22, 2024 at 1:03 AM