Large Millimeter Telescope

The Large Millimeter Telescope (LMT, aka Gran Telescopio Milimétrico, GTM) is a 50-meter diameter telescope at Volcan Sierra Negra, Mexico, aimed at wavelengths on the order of 1 mm, i.e., short microwave and long infrared wavelengths. It is situated at 4,640 metres (15,200 feet) and detects 0.85 to 4 mm (75-350 GHz) signal. At its location, only part of the year provides ideal observation. It does not approach the angular resolution of Atacama Large Millimeter Array (ALMA) but features a much larger field of view. Its first light was in 2011, and went into operation in 2013 using the inner 32 meters of the reflector, with 50 meters becoming operational in 2017. Its angular resolution at 1.1 mm was 8.5 arcsec with the 32-meter reflector and 5.5 arcsec with 50 meters. The 50-meter size gives it the ability to detect a star formation of 10 solar masses per year in galaxies at high redshift. Instruments include:

• SEQUOIA - 32 pixel, 3 mm camera.
• RSR - Redshift Search Receiver - 4 pixel camera covering the 90 GHz atmospheric window to detect redshift of carbon monoxide spectrum features.
• B4R - 2 mm receiver and spectrometer.
• MSIP1mm - single-pixel 1 mm receiver.
• TolTEC - a camera imaging simultaneously in three bands, for rapid surveying.
• MSIP1mm - Event Horizon Telescope (EHT) receiver.

Past:

• AzTEC - 144 pixel 1.1 mm camera, replaced by TolTEC.

Future:

• OMAyA "One Millimeter Array for Astronomy".

LMT suffered a power from August 2023 to March 2024. A later, shorter 2024 outage was due to closure of the access road. (I've also read of outages due to funding.) As of 2/2026, I cannot find information about LMT's current status, but it was said to have participated in the spring 2025 EHT effort.