Keck Instrument Availability for Semester 2025A

Observing at WMKO

Instruments Available for Semester 2025B

For detailed information about the instruments, please check the Instruments Home Page
For information about which instruments can be used on the same night, please check Instrument Sharing
For a Resolving Power vs. Wavelength comparison of Keck instruments, please check this Instrument Comparison graph.

Keck I Instruments are:

        HIRESb (blue x-disperser)
        HIRESr (red x-disperser)
        KPF
        KPF-CC
        LRIS-ADC (red and blue, with ADC)
        LRISp-ADC (polarimeter, with ADC)
        MOSFIRE
        OSIRIS-NGS
        OSIRIS-LGS

Keck II Instruments are:

        DEIMOS - limited availability, see below
        ESI - Scheduled for hibernation at the conclusion of semester 26A
        ESIi (ESI with the Integral Field Unit) - Scheduled for hibernation at the conclusion of semester 26A
        KCWI
        KPIC - limited availability, see below
        NIRSPEC (without AO)
        NIRSPAO-NGS (NIRSPEC with Natural Guide Star AO, see restrictions below) - limited availability, see below
        NIRSPAO-LGS (NIRSPEC with Laser Guide Star AO; see restrictions below) - limited availability, see below
        NIRC2-NGS - limited availability, see below
        NIRC2-LGS - limited availability, see below
        NIRES - Scheduled for hibernation at the conclusion of semester 25B

Subaru Time Exchange Instruments are:

FOCAS, HDS, Hyper Suprime-Cam, IRCS, MOIRCS, PFS, CHARIS, SCExAO, VAMPIRES, REACH, Fast PDI, NsIR, and IRD. See below for limitations.

Telescope Limits

Please note that Keck I and Keck II have different eastern and western telescope limits. This affects the times objects will be available for observing. Objects can be acquired earlier on Keck II and followed later on Keck I.

Special Notes for Semester 2025B:

Keck I Telescope: Keck I telescope will be unavailable for use from August 31 - October 16 for a second planned shutdown to conduct repairs of the telescope pier.

KPF and KPF-CC: The 25B coversheet will contain both the KPF and KPF-CC instrument options. The KPF Community Cadence (KPF-CC) program is operating a queue observation service in 2025B. For PIs who wish to opt in, they must select the KPF-CC instrument on their coversheet. PIs also must submit all proposed observational requests to the queue prior to their TAC's proposal deadline. Much more detail on the KPF-CC program, how to opt-in, and how to submit requests can be found at this link, please read carefully: https://docs.google.com/document/d/1-TfR6lNEtHO3muw_2Sc7l9Klveb3yovMUu28Jeq21t0/edit?usp=sharing

Keck II AO: Keck II AO (Nirc2 and NIRSPAO) will be unavailable for 3 weeks beginning in mid-August.

DEIMOS: Deimos will be unavailable from October 1 through the end of January for the installation of a new science detector.

NIRSPAO/KPIC: Nirspao and KPIC will be available through the end of November. NIRSPAO and KPIC will no longer be available for use once SCALES arrives at the Observatory. PIs may apply and be scheduled for Nirspao and KPIC time in the December-January timeframe, but must be willing to switch to a backup instrument (Nirspec, Nires, Nirc2-NGS) if SCALES installation is ready to commence during these months. For more information on SCALES, see https://arxiv.org/pdf/2208.10721

KPIC: KPIC Phase I capabilities continue to be offered as a facility instrument in 25B, during the timeframe that KPIC is available. More information on KPIC Phase I can be found at KPIC Information

Instrument Hibernation: :WMKO, in consultation with the Science Steering Committee after the receipt of the findings of the Instrument Suite Evolution task force (comprised of members of the WMKO community and WMKO science staff), is undergoing a process of hibernation and eventual decommissioning of instruments in the coming years as new capabilities arrive and to be responsive to pressures on WMKO resources. A hibernated instrument is not available for community use unless there is a significant emergent scientific and strategic need. After a year's hibernation, the hibernated instrument will be completely removed from service and decommissioned. The community should begin planning for the following:

NIRES: NIRES will be hibernated at the conclusion of the 2025B semester.
ESI: ESI will be hibernated at the end of the 2026A semester. ESI will continue to be scheduled in campaign mode to limit the number of reconfigs through each semester.
HIRES: Hires is being considered for hibernation in 2027. A separate communication soliciting feedback will be sent to the community.
Additional instruments are under consideration for hibernation and eventual decommissioning in later semesters, with a focus on those instruments whose capabilities are being significantly superseded by new instrumentation.

NIRSPAO/NIRSPEC: Please note that Nirspec and Nirspao nights will be scheduled in campaign mode to limit the number of reconfigs into AO during the semester. This may impact the ability to schedule certain date critical observations.

At-Home (pajama mode) Observing: At-home observing will continue to be available to observers. Please see https://keckobservatory.atlassian.net/wiki/spaces/MOSD/overview for information about remote observing, including at-home observing.

Time Domain Astronomy: Observers will continue to have the ability to propose both cadence and ToO programs using the cover sheet. Policies related to Target of Opportunity or Cadence proposals can be found at Too Policies and Cadence Policies. These policies are not applicable to Subaru Exchange time. TAC-approved Cross-institutional ToO (TDA) projects will continue to be able to interrupt observers at any Institution, to increase the utility of the ToO process.

Twilight Cadence Observing: The twilight cadence program will continue in 2025A, with NIRC2-NGS and OSIRIS-NGS available for use. Each institution may allocate one twilight cadence program per telescope. Please note that due to ongoing AO upgrades, there will be times in the semester when AO is unavailable for cadence observations (see above). Cadence program PIs are responsible for development of instrument scripts, providing documentation, and training of staff needed to make the cadence program a turnkey operation. More details can be found in the Cadence Policy.

FOCAS, HDS, Hyper Suprime-Cam, IRCS, MOIRCS, PFS, CHARIS+SCExAO, REACH, FastPDI, VAMPIRES, NsIR and IRD will be available at Subaru. Please check the Subaru web site http://www.subarutelescope.org/Observing/index.html for detailed descriptions of these instruments. Please visit https://subarutelescope.org/Observing/Proposals/call.html for instrument restrictions, particularly for visiting (PI-type) instruments SCExAO+CHARIS, IRD, VAMPIRES, Fast PDI, REACH, NsIR and for filter availability of HSC. The SUBARU-KECK exchange will continue to have flexibility with regard to the number of nights available for exchange with the number of nights exchanged determined based on the demand from each community. Subaru ToO observers will continue to be able to interrupt Keck observers on the Subaru Telescope, and Keck ToO observers will be able to interrupt Subaru observers on the Keck Telescope. Compensation will be according to the policy of each observatory.

Subaru observations are executed in "classical" observing mode, except for HSC and PFS observations. Queue observing is the default observing mode for HSC; applicants who desire classical mode with HSC must justify their request. For all classical observations, Subaru may support half night allocations, but whole night allocations are preferred. Please check the HSC queue mode website https://subarutelescope.org/Observing/queue/index.html for more details on HSC observations.

Subaru facility/instrument related restrictions for the 2025B semester:

Telescope Downtime: There is a possibility of three(3) weeks of downtime after October for repairs to the dome's main shutter.
NsIR Downtime: All instruments except for IRD on the NsIR focus - including IRCS, SCExAO(CHARIS, VAMPIRES, FastPDI), and REACH - will be unavailable for about 2-3 months from August. After the installation, all IRCS, SCExAO, and REACH observations will be done with the NBS under shared-risk mode. Please see the IRCS and SCExAO webpage(s) for the possible impacts of the NBS.
SSP: In S25B, PFS-SSP will be assigned about ~10-20 nights over ~3-4 observing runs. IRD-SSP is expected to be completed in S25A.
LGS-AO with TBAD: The laser guide star (LGS) system for AO188 will be operated with TBAD (Transponder Based Aircraft Detector) under shared-risk mode.
AO upgrade: 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 188-element WFS + 3k-element DM), LGS-AO188 mode (uses 188-element WFS + 3k-element DM), and NIRWFS-AO3k mode (uses NIR WFS + 3k-element DM). While NIR WFS provides high-performance AO correction, NGS and LGS mode performance is unchanged because they use 188-element WFS. Please refer to the AO188 webpage(s) for more information.
Rule for queue/classical mode: HSC/PFS Queue-mode programs should consider 30% bad weather factor in order to increase the overall observation completion rate. Accordingly, the requested time for HSC/PFS Queue-mode proposals should not exceed 3.5 nights. It is possible to request up to 5.0 nights in the case of Classical requests.
Available facility instruments: Adaptive Optics (AO188-mode/AO3k-mode), FOCAS, HDS, HSC, IRCS, MOIRCS, PFS.
Available PI-type instruments/devices: CHARIS, FastPDI, IRD, REACH, SCExAO, VAMPIRES, NsIR-WPU, NIR-WFS. Proposals using the visiting instruments/devices must include the relevant PIs as Co-investigators.

LGS-AO: A detailed set of guidelines for LGS-AO nights and information on the capabilities of the systems may be found on the LGS-AO page. Backup programs for LGS proposals are essential. Backup programs for LGS on Keck II may be either NGS programs or NIRES. On Keck I, either NGS-OSIRIS and non-AO HIRES may serve as a backup.

KOA (Keck Observatory Archive): Data from all instruments will be archived in the Keck Observatory Archive (KOA). The default proprietary period for data is 18 months except for data taken with NASA as the allocating institution which has a default proprietary period of 12 months. If observers desire a different proprietary period they may request this through the Keck coversheet. Please see the KOA homepage for information on the archive. Please also see the KOA proprietary period policy.

For detailed information about the instruments, please check the Instruments Home Page

(further observing information)

This page last updated 10February 2025 ccj.
Telescope-scheduling@keck.hawaii.edu