All instruments are restricted for sky visibility as described in the Table below. In addition:
| Accessible | Restricted** | Inaccessible | |
| Declination (non-LGS) | -30° to +73° | -37° to -30°, +73° to +90° |
< -37° |
| Declination, LGS |
-22° to +65° | -27° to -22°, +65° to +68° |
< -27° and > +68° |
| Right Ascension (non-LGS) | 06h to 23h | 04h to 06h, 23h to 01h |
01h to 04h |
| Right Ascension, LGS |
07h to 22h | 05h to 07h, 22h to 00h |
00h to 05h |
**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 2024A:
All instruments are restricted for sky visibility as described in the Table below. In addition:
Gemini South is expected to be closed for the last 10 nights of semester 24A. An engineering shutdown is currently anticipated to run from July 22, 2024 (semester 24A) - Aug 9, 2024 (semester 24B). The 24A shutdown will limit the availability of targets at RA 23 - 02 hours, and back up targets should be prepared.
A FLAMINGOS-2 maintenance intervention is expected to take place during the April 29 - May 17, 2024 period. Time available may be reduced by approximately 20% for targets at RA 10-11 h and 19-20h, and target monitoring or time critical observations with FLAMINGOS-2 may be impacted. Prospective FLAMINGOS-2 PIs should plan their target lists accordingly.
GHOST will be available in limited modes for semester 24A. Potential users should check for updates on the GHOST web pages and/or contact the GHOST instrument team for further details.
SPECIAL NOTE: In addition, GHOST will be offered in limited modes in shared-risk in 23B, via a totally separate Special FT Call for Proposals. Prospective GHOST users for semester 23B and 24A should take special care to ensure that proposals are submitted to their intended semester with the appropriate version of the PIT.
GMOS (South): Following the recent detector upgrades, the associated GMOS-S data reduction pipeline software is currently anticipated to be publicly available during the early part of semester 2024A.
Observations using GeMS are restricted to greater than 45 degrees elevation. How this translates into RA and DEC restrictions is indicated in the Table. 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.
Due to greater-than-average, repeatable, weather loss in May, June and July at Gemini South, the availability of time in the RA 16h - 20h range has been reduced by 10%, RA 20h - 22h by 18%, and RA 23h - 2h by 25%.
Zorro will be available, subject to demand, in the 24A semester. Scheduling will be driven by the demand.
In anticipation of the commissioning of IGRINS-2 at Gemini North, Semester 24A will be the final time in which IGRINS will be offered on Gemini South. In addition, IGRINS will only be available on Gemini South for the months of February, March and April, so IGRINS proposals for semester 24A should only include targets within the RA 05h - 19h range, and time critical observations are limited to this window.
| Accessible | Restricted** | Inaccessible | |
| Declination (non-LGS) | -87° to +22° | -90° to -87°, +22° to +28° |
> +28° |
| Declination, GeMS + GSAOI |
-70° to +10° | -75° to -70°, +10° to +15° |
< -75° and > +15° |
| Right Ascension (non-LGS) | 07h to 18h | 05h to 07h, 23h to 01h |
01h to 05h |
| Right Ascension, GeMS +GSAOI |
07h to 18h | 06h to 07h, 18h to 20h |
20h to 06h |
**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.
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.