This page provides best estimates, at the time of the Call for Proposals, of instrument restrictions and target (RA, DEC) accessibility for 2024B.

All instruments are restricted for sky visibility as described in the Table below. In addition:

• Gemini North is expected to be closed for 12 nights engineering maintenance for the period of October 14 - 25, 2024, and is also currently expected to be closed for 1-3 nights in September (precise dates TBD) for testing and possible repair work.
• Observations using the Gemini North laser guide star (LGS) system are restricted to greater than 40 degrees elevation. How this translates into RA and DEC restrictions is indicated in the table below.
• GMOS (North) - available.  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 (North) - available for imaging, long slit and cross-dispersed spectroscopy. The GNIRS Low-Resolution (LR) IFU will be offered for semester 24B. In addition, the new GNIRS high-resolution (HR) IFU will be offered for the first time in shared-risk mode. Necessary updates to the associated IFU data reduction pipeline software are currently anticipated to be made publicly available during semester 2024B. Users interested in using a GNIRS IFU mode should consult the GNIRS web pages.
• Altair (Adaptive Optics; AO) (North) - Altair NGS modes (for GNIRS imaging and IFU observations) will be available for semester 24B. Altair LGS may also be offered, subject to diagnosis and correction of current ongoing Altair technical issues. Users interested in observations involving the Altair AO system should check the Altair Announcements page for updates on availability.
• `Alopeke (visiting instrument) - will be available during specific blocks, subject to demand, in semester 24B. In addition, ‘Alopeke may also be available outside those blocks on a best-efforts basis. Scheduling will be driven by the demand.
• MAROON-X (visiting instrument) - available during specific blocks, subject to RA demand. Note that it is now possible to check for MAROON-X prior target duplication: please see the instructions in the Phase I checklist for further details.
• TEXES (visiting instrument, North) High resolution (R ~ 4,000-100,000) mid-infrared (4.5-25 micron) spectrometer will be offered for semester 24B, subject to demand.

^**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.

The following Gemini North instrumentation will not be available for Semester 2024B:

• NIFS - no longer available. Programs involving NIR IFU observations should consider the GNIRS LR IFU instead.
• NIRI - no longer available. Near IR imaging (of smaller fields of ~16” field of view) will still be possible using the GNIRS acquisition “keyhole”.
• GRACES (visiting instrument) - no longer available.

All instruments are restricted for sky visibility as described in the Table below. In addition:

• Gemini South is expected to be closed for the first 9 nights of semester 24B (Aug 1 - 9, 2024), as part of an engineering shutdown currently anticipated to run from July 22, 2024 (semester 24A) - Aug 9, 2024 (semester 24B). This shutdown will limit the availability of 24B targets at RA 16 - 18 hours, and back up targets should be included in proposals.
• GMOS (South) - available. The R600 grating will only be available for classical observing.
• GHOST will be offered as part of the regular semester 24B Call for Proposals. The instrument will be available throughout the semester during scheduled blocks. Potential users should check for updates on the GHOST web pages for further details. A clear science target list for each GHOST proposal will also be required, in order to avoid possible conflicts with established GHOST Guaranteed Time target lists.
• FLAMINGOS-2 (0.9-2.4 micron wide-field imager and spectrometer) will be available in imaging, long-slit and MOS modes throughout the semester. The multi-object spectroscopy (MOS) mode allows the simultaneous observation of up to 150 targets per mask over an area of 6’x2’.
• Observations using GSAOI + GeMS are restricted to greater than 45 degrees elevation. How this translates into RA and DEC restrictions is indicated in the Table below. The expectation is to have two or three laser runs of 7 nights, therefore up to about 150 hours will be scheduled at ITAC (Queue only, Bands 1 & 2 with IQ70 & IQ85). However, GeMS availability and scheduling will ultimately be driven by demand.
• Zorro will be available during specific blocks, subject to demand, in semester 24B. Scheduling will be driven by the demand.

^**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.

The following Gemini South instrumentation will not be available for Semester 2024B:

• IGRINS (visiting instrument, South) - no longer available.

At each Gemini telescope, instruments are mounted at the Cassegrain focus on the instrument support structure (ISS). A science fold mirror mounted inside the ISS can be rotated to send the light from the telescope to any of four side-looking ports, or can be retracted so that the light goes to the up-looking port. At each site, the calibration unit and the Adaptive Optics system use two of the side ports, leaving two side-looking and one up-looking port for other instrumentation. As more than three instruments are offered each semester, instrument swaps are required and not all instruments will be available for the entire semester. Instrument swaps are driven by demand and scheduled to minimize impact on the queue. Certain targets or entire programs may not be feasible once the final schedule is determined, at ITAC or thereafter. If an instrument is requested for less than 6% of the Bands 1+2 time, the Observatory reserves the right to limit the RA range available to programs, or to not schedule the instrument.

Non-sidereal targets can have a broader range in RA than indicated in the Tables above due to, for example, the need to observe comets relatively close to the Sun. The ephemeris for any submitted target however must include a position that is accessible between evening and morning twilight at some point in the semester. For rapidly moving targets PIs should specify in the proposal when the target is accessible, and the coordinates of the target at that time, so that the observation can be checked for feasibility.

Gemini Observatory attempts to schedule all time-critical observations whenever possible within the constraints imposed by instrument availability, instrument configuration, weather, and science ranking band. Additionally, nights not scheduled for multi-instrument queue including classical and other observing modes, shutdowns, commissioning, etc., impose additional constraints on time-critical programs. Short observations (~1 hour) can often be accommodated during priority visitor periods. Programs with time-critical observations are asked to include detailed scheduling constraints with their proposal, such that they can be considered along with other constraints when developing the telescope schedule each semester.