Call for Proposals: UC time on the Keck telescopes

Semester 2021B (Aug 1, 2021 through Jan 31, 2022)

Deadline: Proposals are due on Thursday, Mar 18th, 2021 by 5:00 pm PDT*

* Note this deadline is close to the Chandra proposal deadline so please plan accordingly
Please read these guidelines carefully, as several things have changed since last semester.

1.1 Due Date
Proposals for UC observing time on the Keck Telescopes for Semester 2021B are due by 5:00 pm PDT on Thursday, Mar 18th, 2021. There will be 62.5 nights available on K1 and 57 nights available on K2 spread evenly across the semester and lunar phase. There are 7 one-hour Partnership ToO interrupts available.

1.2 Proposal Process
NOTE: There is a new requirement based on the changes to the LMAP proposal changes made by the UCOAC. In normal (non-LMAP) proposals PIs will now have to report if they are a key LMAP member and included in the LMAP management plan.

Due to the likely continued impacts on the observatory and our observing community by COVID-19:
  • We are advising proposers that there may be currently unforeseen impacts on our ability to execute the allocated 21B schedule. In particular, specialty modes (e.g. PyWFS, ESI IFU, VV coronagraphs) may be unavailable for operation.
  • Some instruments and modes of instruments like NIRSPAO and ESI may be scheduled in limited blocks or campaigns to minimize load on support crews.
  • In order to reduce the support load on observatory staff, partial night allocations in 21B may be limited. Proposers should consider whether full night allocations can meet their science goals.
  • See restrictions on ToO observing below.

The principal consideration in evaluating proposals will be the scientific merit of the proposed project. Projects that take maximum advantage of the unique capabilities of the Keck Telescopes will be given high weight. A brief description should be given of backup programs that will be carried out if conditions are not suitable for the primary program. Please see which describes the UC online proposal submission process, and which describes the required sections and their page limits. The Time Allocation Committees take page limits very seriously, so please pay close attention as you draft your proposal.

Keck is continuing the login-password system to allow you to retrieve and modify your coversheets. Returning observers should use the same account information as last semester. New observers may request an account from the page

The coversheet form is available through the login page link above. Once you have created a coversheet and you are logged in, please go to the instructions for submitting Keck proposals at: to create the rest of your proposal as a PDF file to upload to the UC proposal server. Note that the coversheet has been modified again this semester, so please pay close attention when filling it out.

1.3 Be Kind to your TAC Members
Please read the page limits carefully on the keck-guidelines web page ( and adhere to them. TAC members will be instructed to stop reading any text beyond the stated page limits. Note that the text format is 12 point font; single-spaced; one-inch margins.

Although there is not a formal limit on the number of Keck proposals that one PI can submit, experience has shown that TAC members view one PI submitting numerous proposals as a real burden on the reviewing process; it generally does not increase the odds of a PI getting Keck time. Please use moderation.

1.4 Time Domain Astronomy (TDA)
Observers will continue to have the ability to propose both Target of Opportunity (ToO) and Cadence programs using the Keck Cover Sheet. Keck policies related to Target of Opportunity (ToO) and Cadence proposals can be found at and

If your project involves both Classical and TDA observing, you MUST put in two separate cover sheets so that the Keck TDA software can clearly distinguish between the two. Instead of submitting the same text twice, please submit the actual proposal text under the Classical cover sheet; the text submitted under the TDA (ToO or Cadence) cover sheet should merely include the proposal title, PI, and proposal number, together with a sentence stating that the main text can be found under the proposal number of the Classical cover sheet. The Cover Sheet form will not let you submit one proposal requesting both Classical and TDA observing time.

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.

For Semester 2021B, two types of ToO requests can be made. TAC- approved ToO projects which are able to interrupt observers at any of the four institutions, to increase the utility of the ToO process. These are called Partnership ToO proposals. There is a limit to the number of Partnership ToO interrupts. The second kind of TAC approved ToO program (Institutional) can only interrupt UC programs. Note that there is not a limit to the number of “Institutional” ToO interrupts of fellow UC observers. But because UC nights are only a fraction of the total available Keck nights, the probability of a successful ToO interrupt using UC time alone is smaller than for Partnership ToOs. Also note that UC Institutional ToO time can be interrupted by a Partnership ToO, so think through your strategy carefully. Both Partnership and Institutional ToO interrupts are counted in full 1 hour increments even if less than 1 hour of time is used. All ToO proposal requests should be made in units of 1 hour interrupts.

In 2021B, partial-night observations can be interrupted. The Keck guidelines state that “Individual TACs may designate a few nights (partial or whole) as exempt from ToO interrupts. This designation must be scientifically motivated, namely that such interruptions would seriously compromise the scientific return of the entire observing time. Proposers should make any such requests to their individual TACs as part of their observing proposal. Use of these exemptions is expected to be rare.” So if you think your project deserves, for scientific reasons, to have one of these rare exemptions from interruptions, please state so in your proposal and give a very strong justification for your request.

1.5 Cadence Observations
Keck's policies for Cadence observing ( are reasonably complicated. These include a new category called "Partnership Snapshot" observatories. If you are contemplating applying for Cadence time, please read the guidelines carefully.

Keck continues to reconcile cross-institutional cadence and ToO allocations. Scheduled cadence time is returned to the institution at a one to one rate, and ToO time is returned at a rate of two hours for every one hour interruption because the ToO PI will not choose to call for a trigger if the weather is unacceptable.

1.6 Twilight Cadence Observations
In 2021B, institutions will continue to be able to allocate one twilight observing program per telescope, for a total of up to two programs. On Keck I, OSIRIS-NGS (imager only) will be available, and on Keck II NIRC2-NGS will be available. See the Keck Cadence guidelines for details linked on the Instruments Available webpage:

1.7 Large Multi-Year Projects
The Large Multi-Year Project (LMAP) program policy was updated by the UCOAC on 11/18/2020. Please read the new policy for project updates and new proposals.
Large Multi-Year Project (LMAP) programs are UC observing projects with well-defined scientific objectives that require a large number of nights to bring to completion (normally 10 or more nights per semester). The UC LMAP program allows projects extending for more than one semester to be carried out with multi-year approval from the beginning. LMAPs should generally be directed toward obtaining a high quality, coherent, homogeneous data set that will allow scientific questions of major importance to be addressed in a thorough, systematic manner. Please consult for current policies regarding LMAPs.

1.8 At-Home (pajama mode) Observing
  • Keck will support up to two observers for at home observing: one primary and one secondary observer.  Those two individuals may help other team members get set up, but Keck support will be limited for additional observers.
  • At home observing requires the installation of software which only runs on linux and macOS operating systems.
  • Observers using at home observing should plan to work with Keck staff to install and test the software several days ahead of their run to allow time for troubleshooting.

2.0 Notes on Instruments and Availability
See the following web page for detailed notes on the availability of instruments for 2021B: There are quite a few notes for individual instrument availability, so please read quite carefully. Instrument descriptions are at Because 2021B instrument availability is fairly complex, we have not tried to summarize it here.

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, as well as for information on the KOA proprietary period policy.

2.1 Subaru Exchange

The SUBARU-KECK exchange will continue as previous semesters with flexibility as to the number of nights available for exchange. The number of exchanged nights will be determined based on the demand from each community. Keck will offer LRIS, HIRES, OSIRIS, and MOSFIRE on Keck-I, and DEIMOS, ESI, NIRSPEC/NIRSPAO, KCWI, NIRES, and NIRC2 on Keck-II. Subaru will offer FOCAS, HDS, MOIRCS or SWIMS (see note below), IRCS (with NGS/LGSAO188 elements), SCExAO, CHARIS, IRD, VAMPIRES, and Hyper Suprime-Cam (HSC).  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 for more details.

Notes regarding Subaru facility and instrument availability in 21B:
  • Telescope downtime in early August for UPS replacement work.
  • MOIRCS is hibernated S21A-S22B
  • Another consecutive 10 weekdays downtime for PFS installation work
  • HSC is not available for ~2.5 months due to top unit exchange work (postponed from 21A, date TBD)
  • Only NGS mode is available for AO188 observations (no LGS+AO mode again)
  • IRCS is not available in August and September for cold head replacement
  • Quick instrument switching between IRD, REACH, CHARIS + VAMPIRES during the observation (in the same proposal) becomes possible – see Subaru CfP for more details.
  • No big change for HSC queue mode: 1 exchange night = 10 hours including overheads. Please use the overhead calculator to estimate the overheads (
  • Subaru will also be offering visiting instruments FastPDI and MEC in 2021B, both of which are operated with SCExAO. More information can be found here: MEC:
  • Also, please note that "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."

Claire Max
Director, UC Observatories
University of California, Santa Cruz
1156 High Street
Santa Cruz CA 95064