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2024B Call for Proposals

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Gemini Observatory invites its community to propose scientific investigations for the 2024B semester, 1 August 2024 - 31 January 2025.

The table below shows submission deadlines for all Gemini Participants, and the Subaru community under the Gemini/Subaru time exchange. Multi-participant joint proposals should be submitted by the deadline of the participant country to which the Principal Investigator is affiliated. For more on the Gemini proposal submission and time allocation process, please consult the Phase I page.

Participant Submission Deadline
United States April 01, 2024 at 23:59 (Mountain Standard Time)
Canada April 05 (extended from April 02), 2024 at 16:00 (Pacific Daylight Time)
Brazil April 03, 2024 at 23:59 (Brazilian Time)
Argentina April 03, 2024 at 17:00 (Argentina Time)
Korea April 01, 2024 at 23:59 (Korea Standard Time)
Chile April 01, 2024 at 23:59 (Civil Chile Time)
Univ. of Hawaii April 01, 2024 at 10:00 (Hawaii-Aleutian Standard Time)
Subaru Community March 31, 2024 at 23:59 (Hawaii-Aleutian Standard Time)

The Call is open to all participants and host institutions: Argentina, Brazil, Canada, Korea, the United States, Chile and the University of Hawaii. US time is open to all astronomers worldwide including those at non-US institutions, although in that case the proposal must explain why U.S. national facilities are needed. 

Time Available in 2024B

A summary of the time distribution at each telescope is shown in the Table below. More information is available at the time distribution page. At Gemini North, 153 nights are expected to be available for science. At Gemini South, 157 nights are expected to be available for science.

Participant/Type  North hours  South hours Notes Participant/Type  North hours  South hours Notes
US* 597 607 US open skies policy allows PIs from any country to apply. Director's Discretionary 67 68 Open to any astronomer.
Canada** 161 163 Fast Turnaround 130 132 Open to PIs from US, CA, AR, BR & KR. Not open to UH or CL.
Argentina 23 24 Large and Long** 111 113 Pre-allocated in A semesters. In B semesters, open to US and CA PIs.
Brazil 72 76 Guaranteed Time 38 50 For the MAROON-X & GHOST instrument teams.
Korea 83 84 Engineering 305 270
Univ. of Hawaii (host) 150
Chile (host) 152
* The US time available is an estimate that includes deductions for the Gemini Large and Long Programs, the US Long Term programs, and the US space mission support programs.
** The CA time available includes a deduction for the Gemini Large and Long Programs.

New and Notable in 2024B

The following capabilities and announcements are notable for the 2024B semester. Please see the relevant instrument pages and subsections of the call for proposals for details.


  • All proposals to use Gemini in 2024B must use the 2024B Phase 1 template. The template has been designed to enable the anonymous review process, and to make proposals requirements, such as page and figure limits, uniform across the partners.
  • Classical mode observing is offered in semester 2024B for facility instruments only. Priority Visitor mode is offered at both Gemini North and Gemini South; however if circumstances preclude having people on site, then awarded Priority Visitor time will revert to queue. PIs requesting Classical observing must state in their technical justification how the observations could be done in queue mode (with remote eavesdropping for data quality assessment and decision making). The "Bring One, Get One" Student Observer Support Program remains unavailable for semester 24B.
  • GMOS On-Sky Arcs: From 24B, GMOS baseline arcs will be taken on sky mixed with the science observations. For details on the updated GMOS arc baseline policy see this page.
  • Gemini North is expected to be closed for 12 nights engineering maintenance for October 14 - 25, 2024, and for 1-3 nights in September (precise dates TBD) for testing and possible repair work. These dates are provisional, and may be subject to change.
  • Gemini South is expected to be closed for the first 9 nights of semester 24B (Aug 1 - 9, 2024). These dates are provisional, and may be subject to change.
  • Gemini North - GNIRS HR IFU: The new GNIRS High Resolution IFU will be available for shared-risk observations during Semester 24B.
  • Gemini North - TEXES (visiting instrument): Available for Semester 24B, subject to demand.
  • Gemini North - NIFS, NIRI & GRACES: No longer offered.
  • Gemini South - IGRINS: No longer offered.
  • Gemini Observatory currently operates a Graduate Student Visitor Program. Note that all applications for this program should only be made after the conclusion of the ITAC process, and not as part of an initial submission for this Call for Proposals. Applications for the Graduate Student Visitor Program should only be made by successful 24B proposals. Details of the Graduate Student Visitor program are available here.

Summary of 2024B Gemini Capabilities

Gemini North

Targets are generally limited to 17 < RA hours < 13.5 and -37 < DEC degrees < +90. Note that the RA ranges with limited accessibility near the start and end of the semester are typically in very high demand, and so prospective PIs may wish to consider avoiding targets with these RAs, where possible.

Facility instruments offered in 2024B are:

  • Altair AO system: NGS modes. There is currently a technical issue with Altair, a resolution for which is being worked on, and this may impact the availability of  LGS+P1 (super-seeing) and LGS modes in the 2024B semester. Prospective PIs should check the instrument web page for news updates.
  • GMOS North (0.36-1.03 micron imager and spectrometer): Available throughout the semester. The GMOS-N B600 grating will not be offered because of its degraded sensitivity. The R600 grating will only be available for classical observing.
  • GNIRS (1-5 micron spectrometer): Available with or without AO capability. Available with or without AO capability. As before, the short red camera is NOT available. YJHK imaging is available via the acquisition keyhole. The GNIRS LR IFU will be available for science during semester 24B. In addition, the new GNIRS HR IFU will be available for shared-risk observations during semester 24B.

Visiting instruments offered in 2024B (subject to demand) are:

  • 'Alopeke: A dual-channel fast-readout visual-wavelength camera giving simultaneous diffraction-limited images in two filters over a 2.8 arcsec field of view; as well as a wide-field mode which provides simultaneous two-color imaging in standard SDSS filters over a 60" field of view. The scheduling and length of the 'Alopeke visiting block(s) will be subject to demand. ‘Alopeke may also be available outside those blocks on a best-efforts basis. Targets of Opportunity (Rapid or Standard) are accepted for 'Alopeke, but will only be executed during the instrument blocks.
  • MAROON-X: a high-resolution (R~80,000), optical (500 - 900nm) radial velocity (RV) spectrometer,  is open to the community for high precision RV studies as well as general purpose high-resolution spectroscopy.  Please use the Maroon-X Exposure Time Calculator to evaluate the instrument performance.  It is now also possible to check for MAROON-X target duplication: please see the instructions in the Phase I checklist.
  • TEXES: A high resolution (R ~ 4,000-100,000) mid-infrared (4.5-25 micron) spectrometer; available in semester 24B, subject to demand.

Gemini South

Targets are generally limited to 16 < RA hours < 12 and -90° < dec < +28°. There are additional constraints as described in the target accessibility and instrument restrictions page of this Call for Proposals. Note that the RA ranges with limited accessibility near the start and end of the semester are typically in very high demand, and so prospective PIs may wish to consider avoiding targets with these RAs, where possible.

Facility instruments offered in 2024B are:

Visiting instruments offered in 2024B (subject to demand) are:

  • Zorro: a dual-channel fast-readout visual-wavelength camera giving simultaneous diffraction-limited images in two filters over a 2.8 arcsec field of view; as well as a wide-field mode which provides simultaneous two-color imaging in standard SDSS filters over a 60" field of view. The scheduling and length of the Zorro visiting block(s) will be subject to community demand.  Targets of Opportunity (Rapid or Standard) are accepted for Zorro, but will only be executed during the instrument blocks.

Important Dates for 2024B

The deadline for Phase I submission varies with participant (see the submission deadline Table at the top of this CfP). For successful proposals, both queue and classical, the Phase II submission deadline is 18th July 2024. Check the 2024B schedule for key dates and events in the proposal process.

Phase I Submission Guidelines for 2024B

Proposals for time on Gemini, and for time on Subaru via the Gemini-Subaru time exchange program, must use the Gemini Phase I Tool (PIT). Latex and Word templates are available to create pdf attachments which include the science and technical cases, and investigator information. The template has been revised to enable the anonymous review process, and to make proposals requirements uniform across the partners. Two attachments are required for the proposal so that team information can be separated from the science case.

All Gemini proposals requesting time from the US, CA, BR, or AR must be anonymized. Proposals which do not meet the guidelines will be penalized. This applies to proposals requesting time only from these partners, as well as joint proposals requesting time from multiple participants which include any of these partners. This requirement applies whether it is the PI or a co-I that has the relevant partner affiliation.

Specific Timing Windows: In order to maximize the chances of completing observations with timing windows, 24B proposals should:

  • Provide a clear indication of the need for timing windows at Phase 1. If they are highly constraining (e.g. fewer than 6 observing possibilities), then PIs are strongly recommended to list them explicitly.
  • Use observing constraints appropriate to the expected conditions. For example, if the only timing window for your proposal occurs during dark time, you should make sure to choose SB20 or 50 as appropriate.

Additional options in the Time Requests module in the PIT are available for semester 2024B:

  • The Gemini 2024B Phase 1 Tool includes options to specify that the proposal is for the AEON multi-telescope-facility system. 
  • Also in the 2024B Time Requests module, there is an option to identify proposals which have synergies with James Webb Space Telescope science. The goal for providing this proposal category is to encourage development of science programs that benefit from a combination of Gemini and JWST observations.

Time for baseline partner calibrations is automatically added to the total time requested for each target in the PIT. Investigators should continue to include the time associated with overheads (acquisition time, readout time, etc). The ITC output gives overhead estimates. 'Alopeke and Zorro PIs should include program time for PSF standards if they need them. PIs with targets that can be observed from either Gemini North or South (e.g. equatorial targets to be observed with one of the GMOS instruments) can request time with both instruments, in that case the time with each instrument should be halved, and the Observatory will update the observation times when targets are scheduled.

Targets of opportunity proposals must include all instrument configurations which the team may want to use, at Phase 1. This enables automatic creation of templates, and avoids errors at Phase 2.

Subaru Exchange Time 

The exchange of time between the Gemini and Subaru communities will continue in 2024B; around 5 nights are expected to be available on Subaru for the Gemini community via the exchange program. Subaru exchange time is open to all Gemini partners, including Chile. A summary of the Subaru capabilities in 2024B is given below, PIs should also consult the Subaru Call for Proposals.

In addition, the Gemini community can propose shorter programs for Subaru's Service mode. PIs must indicate on the proposal whether regular or service time is requested. Service programs must be short programs of less than 4 hours duration including calibration and overheads, using one of IRCS, HDS, FOCAS or MOIRCS. Up to 1 night is expected to be available in this mode for the Gemini community. Prospective investigators must carefully review the Service Program web page. In particular, some additional, detailed technical information must be provided at the time of Phase-1 submission. Service proposals are reviewed by the National TACs together with the regular proposals.


  • Duplicate Subaru proposals submitted via other routes: If eligible PIs submit a proposal for Gemini Subaru exchange time and also submit the same proposal to a different TAC in parallel (e.g. researchers via the open use time offered in the Subaru Call, Gemini community PIs via the Gemini time-exchange program or Keck community PIs via the Keck time-exchange program), the proposers are asked to explicitly note the double submission in the proposal.
  • Proposal submission: Proposals for time on Subaru via the Gemini time-exchange program are submitted via the normal Gemini Phase I process.
  • HSC proposal length limits: For semester 24B, Gemini users can request no more than 3.5 nights (35 hours science time including overhead) in the case of HSC queue, and no more than 5.0 nights in the case of HSC classical requests.
  • Instrument switches during the night: Switching between IRD, REACH, CHARIS, VAMPIRES, Fast PDI, and MEC during a single or half-night observation is possible. Please check the Subaru Call for Proposals for the time required for switching instruments.
  • Subaru telescope downtime: During semester 2024B, no telescope downtime is scheduled.
  • Subaru instrument and telescope restrictions:
    • The laser guide star (LGS) system for AO188 will be operated with TBAD (Transponder Based Aircraft Detector) with a shared-risk policy.
    • The near-infrared wavefront sensor (NIR WFS) of AO188 is available in shared-risk mode, only for limited modes with IRCS and SCExAO/CHARIS. Please refer to the NIR WFS website and the IRCS webpage for more information. Users planning to submit a proposal must contact the NIR WFS PI and include him in the proposal as a Co-I.
    • The windscreen of the Subaru telescope is out of operation in 2024B, and thus tracking of target may not be possible in high winds. It is recommended that PIs have targets across a range of RAs so that different azimuth angles are available.

Facility instruments offered in 2024B:

Visiting instruments offered in 2024B, are listed below. Proposals to use visiting instruments must include the instrument PIs as Co-investigators. 

  • CHARIS: Coronagraphic High Angular Resolution Imaging Spectrograph - provides high contrast images of exoplanets, disks, brown dwarfs with SCExAO.
  • Fast PDI (in shared-risk mode): polarization differential imaging (PDI) with a high speed (>kHz) near-IR (950 - 1860 nm) low-noise camera (C-RED One), optimized for high contrast imaging of circumstellar disks with SCExAO+AO188. 
  • IRD - Infrared Doppler (in shared-risk mode): infrared high-dispersion, high resolution (up to 70,000) fiber-fed spectrometer. The IRD SSP (Subaru Stragetic Program) was started in 2019A – any IRD proposal must clarify how its scientific aim is different from SSP. The observing mode REACH (SCExAO+IRD), is available (see below).
  • MEC (in shared-risk mode): the MKID Exoplanet Camera is a near-IR (800-1400nm) photon-counting low-resolution (R~5) integral field spectrograph optimized for high contrast imaging with SCExAO+AO188.
  • REACH: REACH can be used simultaneously with CHARIS with any dispersion modes, but the wavelength coverage of CHARIS will be from 1850 nm to the longest wavelengths (please see the CHARIS website for details).
    VAMPIRES : The Visible Aperture Masking Polarimetric Imager for Resolved Exoplanetary Structures (VAMPIRES) is a visible light instrument on the SCExAO system.
  • NsIR Wave Plate Unit: a visiting device for IRCS/SCExAO polarimetry mode.
  • NIR-WFS: Near Infrared Wavefront Sensor. Located inside the AO188 instead of the visible curvature wavefront sensor of AO188 for SCExAO and IRCS.

Other Proposal Opportunities in 2024B

Other proposal opportunities are available at Gemini Observatory in 2023B. These include:

  • The Large And Long Program (LLP) 2024 Call provides an annual opportunity to submit proposals which require either significantly more time than a partner typically approves for a single program, or extends over two to six semesters, or both. Up to 20% of the available time from participating parters (US and Canada) is available for LLPs. LLP proposals are currently being accepted from PIs based at an institution of one of the participating partner countries and who have submitted a letter of intent by the appropriate deadline. The 2024B LLPs proposal submission deadline is April 1, 2024, at 23:59 (Hawaii-Aleutian Standard Time). Further information on LLPs and the LLP proposal process can be found on the Large And Long Programs page. Information on previously accepted LLPs and their science programs is available here.

  • The Fast Turnaround (FT) Program provides monthly opportunities to submit proposals, with successful programs scheduled for observation starting one month after each proposal deadline. Up to 10% of the time at Gemini North and Gemini South is available for the FT programs. PIs must be members of the Argentina, Brazil, Canada, Korea, the United States or Subaru astronomy communities. The University of Hawaii and Chile have both withdrawn from the FT program and therefore UH and Chilean PIs do not have access to FT time. 

  • Poor Weather Proposals are solicited for programs that can use poor, but usable, conditions and are executed when nothing in the regular queue is observable. Proposals can be submitted via the normal TAC process (this call) or at any time. PIs must be based in Gemini participating countries or the host institutions.
  • The Gemini community is eligible to propose HyperSuprimeCam (HSC) filler programs on Subaru. Filler programs are executed in poor observing conditions (typically seeing >1.5 arcseconds, and/or poor transparency) and up to 35 hours can be requested by a filler proposal, although the first 4 hours have priority. Execution is not guaranteed: observations are made only when there is no other program in the HSC queue. In recent semesters, typically of order 15% of HSC time has gone to filler programs. Proposals must be sent through the Subaru submission system (NOT Gemini), and are considered only by the Subaru TAC. Note that only a short text summary of the program is required, not a full detailed Science Justification.

Data Rights, Proprietary Periods and Data Distribution

All data taken with the Gemini telescopes are the property of the Gemini Observatory. Principal investigators of Gemini regular programs (Queue/Classical/Poor Weather) have exclusive access to the data for their program for a period of 12 months. Data acquired as part of a Director's Discretionary (DD) program have a standard proprietary period of 6 months, however in exceptional circumstances the Observatory may remove DD proprietary periods. See the page Data Rights and Proprietary Periods for more information.

All data, including raw and available processed data, obtained with the Gemini telescope are distributed exclusively through the Gemini Observatory Archive. More information about the data distribution is given here.

Supporting Information for the Call for Proposals

Relevant general information related to the applications for time on Gemini Telescopes is presented in the supporting information page. Consult there for the following:

  • Time Allocation Process (National and International Time Allocation Committees)
  • Submitting for time on both telescopes
  • Band 1 Persistence
  • Electronic PIT Submission
  • Joint Proposals
  • Under-utilized Instruments
  • Targets of Opportunity
  • GMOS Mask definitions
  • Poor Weather Programs
  • Exchange Time
  • Target information (guide stars, non-sidereal objects, time-specific observations)
  • Duplicate Observations

Prospective users should also refer to the target and instrument accessibility page, and the instrument pages for detailed and up to date information on instrumentation.

Questions and Answers

All questions concerning proposals, or any other subject, should be made using the Gemini HelpDesk. The system will send the request to your National Gemini Office staff in the first instance who will escalate it to Gemini staff if necessary.

Comments and suggestions on the format and content of this page and supporting pages are welcome, and should be sent to Mark Rawlings.