Call for Proposals

Application Submission Deadline 05:00:00 UTC 22 October 2022
Expected Time Allocation Announcement 23 December 2022
Observing Period 2023-S1 2 January 2023 – 30 June 2023

Announcement of Opportunity (2023-S1)

This Announcement of Opportunity is an invitation to the user-communities of the LMT partners to submit scientific proposals requesting observing time on the 50-meter diameter LMT. The deadline to receive proposals is 05:00 UTC on 22 October 2022. The schedule for the next observing season (2023-S1) is 2 January 2023 – 30 June 2023.

The LMT has recently resumed scientific, engineering and maintenance activities following the long-term closure of the telescope in March 2020 due to the COVID-19 pandemic. The 2023-S1 Call for Proposals represents a new opportunity to submit proposals for scientific projects using the full suite of LMT instrumentation which now includes, for the first time, the availability of TolTEC, a large-format multi-band continuum camera.

It is estimated that approximately 800 hours will be committed to night-time observations of the approved and prioritized scientific targets during the full observing season. The remainder of the available night-time operational hours are expected to be accounted for by weather interruptions and standard observing overheads that include monitoring the focus and calibration of the telescope and instrumentation, amongst other necessary activities.

Given the anticipated significant demand for telescope time, the LMT user-community is encouraged to submit shorter, high-impact scientific projects that will lead to published research papers that demonstrate the unique capabilities of the telescope facility. Opportunities to submit longer-term large projects will be offered in future Calls for Proposals.

A high priority over the next 12-months is to continue to improve the optical efficiency and performance of the telescope, in particular at the shortest millimeter wavelengths, as well to test the feasibility and effectiveness of day-time observations. It is therefore anticipated that a variety of engineering projects and metrology measurements of the primary surface will interrupt the 2023-S1 scientific program when necessary. Furthermore it should be anticipated that the on-set of the “rainy season” will increasingly impact the scheduling of the highest-frequency instruments towards the end of the 2023-S1 semester (LMT-site Weather Conditions).

Further information about this proposal opportunity is presented on the LMT web site and will be summarized in a series of webinars to be announced shortly.

Eligible LMT user-communities

Principal Investigators that are affiliated with national institutions and universities within the eligible LMT user-communities (Mexico, USA and Spain) will be able to submit proposals and share LMT observing time in the following proportions:

  • 70% Mexico – all members of the Mexican national research community (of which 2.5% will be shared with the Spanish national research community);
  • 15% University of Massachusetts Amherst (UMASS), USA – all members of the UMASS and Five Colleges research community;
  • 15% USA – all members of the US national research community.

The telescope time associated with each scheduled project will be allocated (charged) to a particular observing queue of the LMT user-communities according to the affiliation of the Principal Investigator. The affiliation of co-investigators, including those external to the eligible LMT user-communities, does not impact the time allocated (charged) to each user-community. For further information on time allocation, please refer to the “Observing Procedures” information page.

Non-standard Types of Proposals

The LMT has developed new policies concerning the types of non-standard proposals that may be submitted to the proposal review. We summarize each below:

  • Policies have been developed for “Large Projects” which exceed a specific number of hours. At this time the boundary between a “Large Project” and a “Standard Project” is set to 35 hours. For the 2023-S1 semester, we will not accept proposals in the “Large Project” category requesting more than 35 hours. Please see the “Types of Proposals” page for further information.
  • Policies for submission of “Target of Opportunity” (ToO) and “Director’s Discretionary Time” (DDT) proposals are described in the “Types of Proposals” information page. As stated in the policy, ToO proposals, which involve targets requiring special scheduling, are considered as a part of our normal review process and should be submitted in response to this call for proposals. DDT proposals follow a special procedure for submission and review that falls outside the normal review process.
  • The policy for inclusion of LMT in VLBI experiments is stated on the “Types of Proposals” information page. As in past years, we require proposals for participation of LMT in VLBI networks to be submitted to the normal review process by a member of one of the LMT user communities.

Special Notice about “Carryover” Proposals from 2021-S1 Review

Those projects previously assigned carry-over status following the review of the scientific proposals submitted to the 2021-S1 Call for Proposals will not be scheduled for observations beyond the end of 2022. If desired, these same projects may be updated and resubmitted to the current 2023-S1 Call for Proposals and will be considered as new projects during the review process.

Available Scientific Instruments

In the observing period 2023-S1 the LMT will offer the opportunity to conduct observations with the following instruments: TolTEC, SEQUOIA, Redshift Search Receiver (RSR), B4R and MSIP1mm. Summaries of instrument capabilities, observing modes, and time calculators can be found on the “Instrumentation” webpage. Please refer to the LMT “Telescope Description” page for details on the telescope design and function.

The TolTEC, 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. All observations with these instruments are carried out by a trained observatory staff using a flexible queue and are processed by a dedicated data reduction pipeline. Each proposing team should read the instrument descriptions carefully and propose only the supported observing modes for each instrument. Proposals requiring a non-standard mode should first contact the LMT Helpdesk at least one week before the proposal deadline to establish its technical feasibility prior to submitting the proposal.

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 Bunyo Hatsukade ( to discuss their scientific interest and collaboration before submitting a proposal.

Shared Risk Status of TolTEC Instrument

TolTEC will operate as a “shared risk” instrument for the 2023-S1 semester. At this time, the commissioning of TolTEC has not allowed estimation of the instrument mapping speed under the best weather conditions. As a consequence, our estimates of this quantity for the coming semester are uncertain. Therefore, in order to allow TolTEC proposals to be submitted, we have estimated the mapping speed based on commissioning data and reasonable assumptions about the atmosphere and the telescope surface accuracy. Users requesting TolTEC time should make use of the observing time calculator provided with this call for proposals. It is important to consider the uncertainty in the mapping speed of TolTEC when planning projects for this proposal review.

Given the uncertainty in the required observing time to reach a specific sensitivity and our interest in offering opportunities for TolTEC observations to as many members of the LMT user-communities as possible in this initial season, TolTEC proposals should be limited to a maximum of 5 hours as determined by the sensitivity calculator.

Proposal Submission Process

The proposal submission process is identical for all members of the eligible scientific communities. LMT observing proposals will be made through a simple web-based form ( Proposals will be required to include a list of participating researchers, a description of the scientific goals and technical feasibility using the requested instruments, and a justification of any special scheduling or weather requirements.

Further details, instructions, and resources on how to prepare and submit a scientific proposal to the LMT can be found on the “Proposal Guidance” information page.

Dual Anonymous Proposal Review

Starting with the 2023-S1 proposal review, the LMT proposal review will be carried out as a “dual anonymous” review, and all proposals must be submitted in a format that preserves the anonymity of the proposal team. Please see the information page describing the dual anonymous format and procedures for preparation of dual anonymous proposals.

Proposal Review and Telescope Time Allocation

All proposals will be subject to a technical assessment prior to a scientific review conducted by a Time Allocation Committee constituted by members of the eligible user-communities, and supported by independent external expert evaluations. Each user-community will provide a unified prioritized list of proposals covering all scientific areas, based primarily on their anticipated scientific impact, that will be merged into the LMT observing schedule.

The full and proportionate allocation of observing time for the prioritized scientific projects from each user-community will be flexibly scheduled during the observing season to maximize the efficiency of the overall scientific program and the telescope operation. Further information regarding the proposal review process and Time Allocation Committee can be found on the “Proposal Review” webpage.

We anticipate the scientific and technical reviews to be completed by 23 December 2023.

Observations will be flexibly scheduled in the observing queue; successful PIs will be contacted regarding the creation of observing scripts. For more information regarding science observing, see the “Observing Procedures” webpage.

LMT Help Desk

For additional general information on the Call for Proposals, or for assistance with the proposal submission process, please contact the LMT Help Desk.