• About DARP:
  Korea will install the DARP (Dual Anonymous Review Process) system from 25B semester. All Gemini proposals requesting time from the US, CA, BR, or AR have been following the DARP policy since 2021. For the Korean Gemini Users, 1yr (or plus) of a grace period (i.e. no penalty to proposals that do not meet the DARP policy) will be given so that they can be well trained/prepared for the DARP system. Korea will fully adopt the DARP policy in the proposal review process from 26B or 27A.

  Here is a brief summary for the DARP policy:

  Guideline for PIs

  • Enter information of the proposing team with the Phase I Tool (PIT) as usual.
  • Use the FT specific template.
  • The proposal template has been updated to be compliant with DARP starting on Feb 1, 2021
  • Avoid mentioning names and affiliations of the team in the PDF attachment that could be used to identify the proposing team.
  • Avoid claiming ownership of past work. (E.g., “my successful Gemini program in the previous semester (GS-18A-xxx)”, or “our analysis shown in Doe et al. 2020…”)
  • Including text in proposals discussing previous use of Gemini is ok, as long as that work is not referenced and program IDs are not listed.
  • Cite references in passive third person, e.g., “Analysis shown in Doe et al. 2020”, including references to data and software.
  • Do describe the proposed work, e.g., “We propose to do the following…”, or “We will measure the effects of …”
  • Unpublished work can be referred to as “obtained in private communication” or “from private consultation”.

  Guideline for Reviewers

  • Accept the assigned proposals based on abstracts whether you can provide an unbiased review or not.
  • Review proposals solely based on the scientific merit of what is proposed.
  • Do not spend any time attempting to identify the PI or the team. Even if you think you know, you can be wrong.
  • Utilize neutral pronouns (they/the PI/the team) when you write comments.
  • Flag the proposals that have not been sufficiently anonymized but DO NOT penalize them by lowering grades. (The FT support team will check the flagged proposals and send any violations to the Gemini Directorate for review.)

• All proposals to use Gemini in 2025A must use the 2025A Phase I template. When preparing PDF attachments, prospective PIs must follow the proposals template font size requirements in all cases, and avoid using smaller fonts in all sections of Gemini proposals (including in figures and tables).

• Classical mode observing is offered in semester 2025A for facility instruments only.

• Priority Visitor (PV) mode is offered at both Gemini North and Gemini South. If circumstances preclude having people on-site, programs awarded PV time will revert to queue mode. 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 25A.

• Rapid Target of Opportunity (rToO) Proposals: These can be accommodated for most instruments and their modes (and this includes non-LGS modes), subject to instrument availability on the dates upon which observations are triggered.

• GMOS On-Sky Arcs: GMOS baseline arcs are now taken on sky mixed with the science observations. For details on the updated GMOS arc baseline policy please see this page.

• Gemini North Engineering Time:
  • At some point in the semester, we anticipate taking the top end off for testing of new control computers/electronics with the tip-tilt system. The work, when it happens, is expected to last three weeks. We will avoid the period of peak RA demand (March-April) but cannot be precise at the time of this Call. If you have targets at the start or end of the semester, you should identify alternates if possible.
  • We also anticipate commencing work in June on the GNIRS camera turret and other issues, including reinstating the short-red camera mode. This requires an extended period - of three or four months - with the instrument in the Hilo lab, and you should assume that GNIRS will be unavailable for the last two months of 2025A.

• Gemini South is expected to be closed for the last 11 nights of semester 25A (July 21 - 31). These dates are provisional, and may be subject to change.

• Gemini North - IGRINS-2: The new IGRINS-2 instrument will be available for shared-risk observations during semester 25A. For further information, please see here.

• Gemini North - NIFS, NIRI & GRACES: No longer offered.

• Gemini South - GHOST PIs to receive reduced data products: The US NGO, in collaboration with Gemini, will offer reduced spectra for GHOST programs from all partner countries. The reduced files will be available through the Gemini Observatory Archive, together with the raw data.

• The Gemini Observatory Graduate Student Visitor Program is temporarily suspended for semester 25A. Details of the Graduate Student Visitor program are available here.

• 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.

• Additional options in the Time Requests module in the PIT are available for semester 2025A:
  • The Gemini 2025A Phase 1 Tool includes options to specify that the proposal is for the Aeon multi-telescope-facility system.
  • Also in the 2025A 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. More information is available here.

Gemini North:

** Due to limited sky availability during the semester, GMOS MOS programs requiring pre-imaging should not have targets in this region, and other programs with targets in this region should not require a large amount of time, or have strict timing or observing constraints.

Gemini South:

** Due to limited sky availability during the semester, GMOS and FLAMINGOS-2 MOS programs requiring pre-imaging should not have targets in this region, and other programs with targets in this region should not require a large amount of time, or have strict timing or observing constraints.

Gemini North:
Facility Instruments:

• 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 2025A 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.

• IGRINS-2: New high-resolution (R~45,000) near-infrared spectrograph covering the wavelength range of 1.49-1.80μm (H-band) and 1.96-2.46μm (K-band) in a single exposure. Offered in shared-risk mode for semester 25A during specific blocks, subject to RA demand.

• GNIRS (1-5 micron spectrometer): Currently anticipated to be available for the period of February - May in 25A (see the preceding “New and Notable” section for further details). GNIRS can be used 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- and HR-IFUs are available for science during semester 25A.

Visiting Instruments:

• 'Alopeke: A dual-channel fast-readout visual-wavelength camera giving simultaneous diffraction-limited images (via speckle reconstruction) in two filters over a 2.8 arcsec field of view; as well as a wide-field mode which provides simultaneous two-color, non-speckle 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. Available during specific blocks, subject to RA demand. 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.

Gemini South:
Facility Instruments:

• GMOS South (0.36-1.03 micron imager and spectrometer): Available throughout the semester. The R600 grating will only be available for classical observing.

• FLAMINGOS-2 (0.9-2.4 micron wide-field imager and spectrometer): Available in imaging, long-slit and MOS modes throughout the semester.

• GSAOI (0.9-2.4 micron adaptive optics imager) with the GeMS Adaptive Optics system: Due to guide star limitations, please check the availability of Guide Star constellations using the Observing Tool before submitting a proposal. Observations in IQ85 are possible for programs that can use delivered images with full-width half-maximum of ~0.2 arcseconds as opposed to the ≤ 0.1 arcseconds delivered in IQ70 or IQ20 conditions. Observations under non-photometric conditions with 0.1 mag uniform extinction are also possible under very good IQ conditions. The expectation is to have two or three laser runs of 7 nights each during the semester, the actual schedule will be based on the demand from the community.

• GHOST: Available throughout the semester during scheduled blocks. Potential users should check for updates on the GHOST web pages for further details and status updates.

Visiting Instruments:

• Zorro: A dual-channel fast-readout visual-wavelength camera giving simultaneous diffraction-limited images (via speckle reconstruction) in two filters over a 2.8 arcsec field of view; as well as a wide-field mode which provides simultaneous two-color, non-speckle 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 demand. Targets of Opportunity (Rapid or Standard) are accepted for Zorro, but will only be executed during the instrument blocks.

The exchange of time between the Gemini and Subaru communities will continue in 2025A; around 5 nights are expected to be available on Subaru for the Gemini community via the exchange program. A summary of the Subaru capabilities in 2025A 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. Around 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.

Details:

• 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.

• Queue mode weather factor: HSC/PFS queue mode proposal time requests must include an additional 30%, in order to account for the impact of poor weather on this queue.

• HSC/PFS queue proposal length limits: For semester 25A, Gemini users can request no more than 3.5 nights (35 hours science time including overheads) in the case of HSC/PFS queue, and no more than 5.0 nights in the case of HSC classical requests.

• Subaru Strategic Programs (SSP): The IRD SSP will be allocated the final 6 nights of the semester. In addition, if the PFS SSP is accepted, it will be assigned up to 36 nights in semester 25A, with the result that only a limited number of available dark nights for normal programs will be available.

• Deformable Mirror (DM) upgrade for AO188: As part of the AO3k project, the DM has been upgraded from a 188-element bimorph mirror to a 3228-actuator magnetic mirror. AO188 provides three modes:
  • NGS/AO188 mode: Uses the 188-element Wave Front Sensor (WFS) + 3k-element DM);
  • LGS/AO188 mode: Uses the 188-element WFS + 3k-element DM;
  • NIRWFS/AO3k mode: Uses the NIR WFS + 3k-element DM.

While the NIR WFS provides high-performance AO correction, NGS and LGS mode performance is unchanged because they use 188-element WFS. Please consult the AO3k web page for more information.

• Instrument switches during the night: Switching between IRD, REACH, CHARIS, VAMPIRES and Fast PDI 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 / instrument downtime:
  • Engineering Downtime: During semester 2025A, the telescope is expected to be closed for approximately 3 nights in February or early March for electrical work.
  • NsIR Downtime: Due to installation work on the Nasmyth Beam Switcher (NBS), all instruments except for IRD on the NsIR focus - including IRCS, SCExAO, CHARIS, VAMPIRES, Fast PDI and REACH - will be unavailable for approximately 2.5 months between late March and July.
• 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. Please consult the AO188 web page for the latest information.
  • The windscreen of the Subaru telescope is out of operation in 2025A, and thus tracking of targets 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.