Sunset at the LMT site.

Proposal Submission Process

The Large Millimeter Telescope Alfonso Serrano (LMT) invites members of the Mexican, U.S. and Spanish astronomy research communities to participate in the open call for scientific observing proposals (2021-S1).

The LMT has been closed for scientific operations since late March 2020 due to the COVID-19 pandemic situation. The current schedule to re-open the telescope, perform essential maintenance and prepare the telescope systems, equipment and instruments for scientific observations is unclear. However we are hopeful that the situation will improve and enable the start of a new scientific program in the spring of 2021.

In preparation for this opportunity we are opening the call to receive scientific proposals for night-time observations with the 50-meter LMT during the 6-month observing season 2021-S1 that will run from March to September 2021.

LMT Science Announcement of Opportunity

All interested applicants for LMT science observations should read the Announcement of Opportunity that contains information regarding guidelines for proposers, the affiliation requirements of eligible Principal Investigators, a summary of the proposal review process and the selection criteria for the prioritization of projects to be submitted to the flexibly-scheduled observing queue.

Schedule for Science Proposal Submission & 2021-S1 Observing Period

  • Deadline for submission of science proposals: December 21st 2020, midnight central daylight time (24:00 CDT)
  • Observing period 2021-S1 begins: March 15th 2021
  • Observing period 2021-S1 ends: September 14th 2021

Instructions for submission of LMT science proposals

The LMT proposal submission tool is based on a similar system developed for the JCMT, and provides the tools to register, submit and monitor the status of all LMT proposals. Information regarding the proposal title, abstract, principal investigator and contact details will be entered directly into the online submission form. The list of astronomical targets and selection of instruments, and the scientific and technical justifications (including figures, tables and references) can also be entered directly into the online submission form or uploaded as separate documents.

The science observing proposals must be written in English. The scientific and technical proposal, if uploaded as two separate documents (PDFs), will be formatted on Letter-sized paper with a font size not smaller than 11 points, and all page margins must be at least 2cm. A total of five pages are available to present the scientific case: a maximum of two pages to justify and describe the case, and additional two pages for figures and tables, and a fifth page for references. The technical justification should be uploaded in a separate single-page document. PDFs should not exceed 5Mb. If edited on-line, the scientific justification and references should not exceed the word limit of 2100 words. A maximum of 4 figures can be uploaded to the on-line system, each with a caption that does not exceed 250 words. If edited on-line, the technical justification should not exceed the word limit of 600 words, and a single figure (or table) may be uploaded to the on-line system with a caption not exceeding 250 words.

Instruments, Sensitivities and Integration Times

A preliminary value of 98 microns r.m.s. is calculated for the total optical error budget, derived from measured deformations in the optics of the 50-meter primary reflector and secondary reflector, plus estimates of the impact of environmental effects (wind loading and temperature gradients in the antenna support structure) on the primary surface. We expect to improve the primary surface accuracy during the 2021-S1 observing period. However this estimated error of 98 microns r.m.s. is the default value used in the current determination of the sensitivities of the scientific instruments.

The LMT primary reflector is set with an active surface control system uses a model to continuously correct the gravitational deformations of the primary reflector surface as the telescope moves in elevation. Over an elevation range of ~20 to 80 degrees the telescope has a measured constant and maximum aperture efficiency or gain.

The following instruments will be available for science observations during the next observing season (2021-S1):

  • RSR
  • B4R (see note below regarding scientific collaboration with the B4R instrument team)
  • MSIP1mm

The SEQUOIA, RSR and MSIP1mm instruments and data reduction software are fully supported by the LMT and hence no collaboration with members of their instrument teams is required. For specific questions related to the use of these scientific instruments please contact Gopal Narayanan (href=””> In contrast, the 2mm B4R instrument has been developed and funded independently with no participation from the LMT partners. The B4R team in Japan will provide the technical support and assistance during the preparation of proposals, scientific observations and the data-analysis for all scheduled projects. Therefore the use of the B4R instrument requires a scientific collaboration with the B4R team. Principal Investigators requesting to use the B4R instrument should first contact Ryohei Kawabe ( to discuss their scientific interest and collaboration before submitting a proposal.

Integration time and instrument sensitivity calculators are provided in the LMT proposal submission tool.

During the spring and summer of 2021, the LMT will program a number of necessary engineering projects that will require the temporary suspension of night-time scientific observations. Furthermore the anticipated installation and commissioning activities of new scientific instruments, as well as the more unpredictable weather conditions during the “rainy season”, will also impact the scheduling of the higher-frequency instruments during the 2021-S1 observing period (with less than 30% of the weather conditions suitable for sensitive 1mm observations).

Scientific observations will be conducted at night-time starting approximately 2 hours after sunset, to allow the telescope to thermally stabilize, and observations will continue until sunrise. It is expected that a maximum of 600 hours of observing time for on-source scientific observations will be available in the 2021-S1 observing season. The exact division of scheduled observing time between the instruments will depend on the scientific priority awarded to the individual projects, and the suitability of the weather conditions for the use of those instruments.

Atmospheric Quality Specifications

Atmospheric opacities (τ225) are measured with a sky-tipping radiometer operating at 225 GHz. The reported atmospheric opacities are measured towards the zenith. Monthly-averaged values of the expected atmospheric opacity at the LMT site can be found in the Sierra Negra Metereological Monitoring page.

Additional attention and justification should be provided in the scientific and technical case when the lowest frequency receivers (SEQUOIA and RSR) require the less frequent and better observing conditions (τ225 < 0.15) during the spring and summer months. Prioritized proposals with more relaxed weather and atmospheric quality specifications will always have a higher probability to be completed during any given observing season.