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 m of the reflector, with 50 m becoming operational in 2017. Its angular resolution at 1.1 mm was 8.5 arcsec with the 32-m reflector and 5.5 arcsec with 50 m. The 50-m 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. As of 1/2025, LMT participation in EHT's 2025 observation is planned.