Observing at WMKO

Instruments Available for Semester 2021B

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
a Resolving Power vs. Wavelength comparison of Keck instruments, please check this Instrument Comparison graph.

Keck 1 Instruments are:

        HIRESb (blue x-disperser)
        HIRESr (red x-disperser)
        LRIS-ADC (red and blue, with ADC)
        LRISp-ADC (polarimeter, with ADC) unavailable in 21B, see below

Keck 2 Instruments are:

        DEIMOS please see note below
        ESIi (ESI with the Integral Field Unit)
        NIRSPEC (without AO)
        NIRSPAO-NGS (NIRSPEC with Natural Guide Star AO, see restrictions below)
        NIRSPAO-LGS (NIRSPEC with Laser Guide Star AO; see restrictions below)
        NIRC2-LGS please see restriction for NIRC2-NGS/LGS/PY use of the vector vortex coronagraph below
        NIRC2-PY (NIRC2-NGS with the Pyramid Wavefront Sensor)


Subaru Time Exchange Instruments are:

FOCAS, HDS, Hyper Suprime-Cam, IRCS, SWIMS, CHARIS+SCExAO, VAMPIRES, REACH, 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 2021B:

Due to likely continued impacts on the observatory and our observing community by COVID-19:

LRISp: LRIS with polarimeter will not be available in 2021B while the polarimeter undergoes repair.

LRIS: Replacement of the LRIS red detector is expected in April 2021. We expect that there will be no restrictions on its use in 2021B.


Please see the NIRC2 manual https://www2.keck.hawaii.edu/inst/nirc2/ObserversManual.html#Section5.2.2 for information about vortex operations.

DEIMOS: The top-left CCD on the detector mosaic is ~4 times noisier than the rest of the CCDs. Please see https://www2.keck.hawaii.edu/inst/deimos/detector_issues.html for guidelines on how to design your MOS masks with this issue in mind.

At-Home (pajama mode) Observing:

Target of Opportunity Observations: ToOs will be limited to instruments currently in use and must be triggered prior to 4:00 pm HST. All ToO observing teams should set up "at-home" observing at the beginning of the semester, well ahead of any possible ToO trigger events.

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 2021B, with NIRC2-NGS and OSIRIS-NGS available for use. Each institution may allocate one twilight cadence program per telescope. More details can be found in the Cadence Policy.

FOCAS, HDS, Hyper Suprime-Cam, IRCS, SWIMS, CHARIS+SCExAO, REACH, FastPDI, MEC, VAMPIRES, and IRD will be available. Please check the Subaru web site http://www.subarutelescope.org/Observing/index.html for detailed descriptions of these instruments. Please visit http://www.naoj.org/Observing/Proposals/Submit/call.html for instrument restrictions, particularly for visiting (PI-type) instruments SCExAO+CHARIS, IRD, VAMPIRES, SWIMS, Fast PDI, MEC, REACH, 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. In 21B, Subaru ToO observers will 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 will be executed in "classical" observing mode. Subaru may support half night allocations, but whole night allocations are preferred. For HSC programs, Subaru may support "queue" observing mode if specified in the proposal, which may allow more flexible allocation such as e.g. very short 0.25 night request. Please check the HSC queue mode website https://www.naoj.org/Observing/queue/index.html for more details.

Subaru facility/instrument related restrictions for the 2021B semester:

  1. Telescope downtime in early August for UPS replacement work.
  2. MOIRCS is hibernated S21A-S22B
  3. Another consecutive 10 weekdays downtime for PFS installation work
  4. HSC is not available for ~2.5 months due to top unit exchange work (postponed from 21A, date TBD)
  5. Only NGS mode is available for AO188 observations (no LGS+AO mode again)
  6. IRCS is not available in August and September for cold head replacement
  7. Quick instrument switching between IRD, REACH, CHARIS + VAMPIRES during the observation (in the same proposal) becomes possible see Subaru CfP for more details.
  8. No big change for HSC queue mode: 1 exchange night = 10 hours including overheads. Please use the overhead calculator to estimate the overheads https://www.naoj.org/cgi-bin/ohc.cgi
  9. NsIR Wave Plate Unit (a visiting device for IRCS/SCExAO polarimetry mode) is also available as a visiting device - proposals using this device needs to contact the relevant PI of this unit in advance

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.

NIRSPAO is scheduled in campaign mode given limited demand for this configuration. If there are insufficient requests for its use, NIRSPAO may not be scheduled in a given semester.

KOA (Keck Observatory Archive): Data from all instruments will be archived in the Keck Observatory Archive (KOA). The default proprietary period for all data is 18 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 05 February 2021 ccj.