CFHT Call for Proposals


The 2025A call for proposals for Canada (NRC), France (CNRS), ASIAA, and NAOC opens August 21 at 23h59 UT.

The deadline is September 19 at 23h59 UT for NRC and CNRS, and 23h59 CST for ASIAA and NAOC.
GRACES is no longer offered at Gemini and the CFHT/Gemini/GRACES exchange program has ended.

2024B DDT proposals - CFHT users interested in submitting a Director's Discretionary Time proposal for 24B are invited to read the Phase 1 Proposal Submission Instructions for information about the QSO Mode and our instruments, and the K1 tutorial for login information and help with the UI. DDT proposals must be submitted using Kealahou K1 after selecting the Discretionary agency. Kealahou now sends submission notifications. Saving a PDF for the record is recommended.

2025A proposals - CFHT users from the NRC (Canada), CNRS (France), ASIAA, or NAOC agencies and partners interested in submitting a proposal for semester 2025A are invited to first read this page for specific instructions regarding semester 2025A. The Phase 1 Proposal Submission Instructions provides important information about the QSO Mode, links to all instruments, their ETC, details of the overheads, and other important points specific to each instrument. The K1 tutorial includes login information for returning and new users, character limits and page limits for various sections, instructions on how to invite collaborators, and other details for each of the sections. Proposals must be submitted using Kealahou K1 after selecting the proper semester and agency. Kealahou now sends submission notifications. Saving a PDF for the record is recommended.

Prospective users applying for University of Hawai’i should continue to use their respective agency's proposal submission tools.

Information on 2025A      [1 Feb 2025 - 31 Jul 2025]

News and specific notes for semester 2025A
Important technical notes
Additional instructions for Canadian proposals
Snapshot programs


News and specific notes for semester 2025A [Up]

WIRCam The filters available at the start of semester will be Y, J, H, Ks, H2, BrG, KCont, and LowOH1. The broad-band filters Y, J, H, Ks are always available. If you need a narrow-band filter currently not in WIRCam, you must provide a strong case justifying why the requested narrow band filter is essential for your science goals, especially pointing out why you cannot use the filters currently available on the filter wheel.

Also note that even if you are awarded time, there is no guarantee your requested filter change will happen; you may be superseded by a higher ranked program also requesting another filter exchange.

For stars brighter than the saturation limits indicated on the Performance Summary page, the Staring Mode may be an appropriate option. Please contact the Instrument Scientist (-=devost=- at cfht.hawaii.edu) for more details.

New SITELLE filters Three new filters (SN4 at Halpha, SN5, SN6) are now available for regular proposals requesting SITELLE. The SN5 and SN6 filters are the property of Dr. Zhenya Zheng. To avoid duplicating scientific projects and goals, teams interested in using these filters must contact zhengzy@shao.ac.cn to initiate a discussion before writing a proposal. Do not hesitate to contact the SITELLE instrument scientist (epinat@cfht.hawaii.edu) for help and more advice regarding proposal preparation with these filters.

Following the analysis of the commissioning data for the new filters obtained in 24A, some recommendations on how to use the filters and prepare observing proposals with these new filters have been prepared. More details are provided on https://www.cfht.hawaii.edu/Instruments/Sitelle/SITELLE_new_filters.pdf.

We recommend using exposure times per steps larger than 16s for the SN4 and SN5 filters (ideally around 40s) and larger than 8s for the SN6 filter (ideally 20s) when sources have emission lines fainter than 1e15 erg/s/cm2/arcsec2. For brighter sources, this limit can be linearly relaxed dow to 3s at 1e14 erg/s/cm2/arcsec2. We also recommend using a spectral resolution lower than 12500, but it can reach 15000 if needed and if the object does not extend all over the field of view. The number of steps scales linearly with the spectral resolution (Nsteps = dNsteps/dR x R). The number of steps is Nsteps = 0.094 x R for the SN4 filter, Nsteps = 0.108 x R for the SN5 filter and Nsteps = 0.173 x R for the SN6 filter.

The new narrow-band filters must be preferred to larger-band filters in the following cases:

  1. Faint object not within the reach of the larger band filters in reasonable exposure times (typically lines with SB<1e16 erg/s/cm2/arcsec2 without any binning). Compared to the SN3 filter, observations with the SN4 filter reach the same depth for total on-source exposure three times lower, or need the same total on-source exposure time to reach a S/N 1.7 times larger.
  2. Only a few lines are needed for the scientific analysis (e.g. only Ha and NII for SN4, or only OIII5007 for SN5).
  3. A high spectral resolution is needed for e.g. kinematics purposes for relatively bright sources.

In order to prepare observing proposals, the S/N or the total exposure time can be scaled as follows:

For the SN4 filter, use the ETC with the SN3 filter, then scale

  • the S/N for a given total on-source by a factor 1.7
  • or, the total exposure for a given S/N by a factor 1/3

For the SN5 filter, use the ETC with the SN2 filter, then scale

  • the S/N for a given total on-source by a factor 2
  • or, the total exposure for a given S/N by a factor 1/4

For the SN6 filter, use the ETC with the C3 filter, then scale

  • the S/N for a given total on-source by a factor 1.4
  • or, the total exposure for a given S/N by a factor 1/2

The time needed per steps can be inferred by dividing the total on-source exposure by the number of steps. The overheads are then estimated by counting 4.1s per step.

Time available The 2025 share of observing time is not firmly established yet. During semester 25A, 32 nights are reserved for the MegaCam Large Programs UNIONS and CLASSY. The UNIONS fields are observable during the first half of the semester. The CLASSY observations will take advantage of the dark runs in Jan/Feb and Mar/Apr. CFHT may start observations for a new Large Program on ESPaDOnS and/or SPIRou. Those exact allocations will be announced in Oct/Nov. The allocations listed below assume that the associate partners, China (NAOC) and Taiwan (ASIAA), use a combined total of 7 nights.

  • Canada (NRC) and France (CNRS): between 15 and 51 nights for PI programs
  • University of Hawaii: Approximatively 24 nights for PI programs
  • Taiwan (ASIAA): Up to 5 nights for PI programs
  • China (NAOC): Up to 15 nights for PI programs

Over the whole semester, about half of the nights have the Moon illumination less or equal to 50% (Dark time), and half have the Moon illumination greater than 50% (Bright time). The dark time is split between MegaCam and SITELLE and the bright time between ESPaDOnS, WIRCam, and SPIRou.


Technical notes [Up]

Start and end times (twilights) per instrument For time-constrained observations (such as transits with SPIRou), it may be important to consider the nightly start and end time for each instrument:

  • MegaCam and SITELLE: observing starts and ends at the 12deg twilights
  • WIRCam, ESPaDOnS, and SPIRou: observing starts and ends at the 8deg twilights

Important telescope limits

Please take into account the following operational constraints and ensure your proposal meets all of them:

ParameterLimit or constraintNote
MegaCam and SITELLE observationsbetween 12deg twilightsplease mention if observations need to wait for the 18deg twilight
WIRCam, ESPaDOnS and SPIRou observationsbetween 8deg twilights
Hour angle limits+/- 5h30
Airmass limit for MegaCam and WIRCam2.7622deg elevation limit
Airmass limit for SITELLE1.65
Declination limits for SITELLE-23deg to +63.5deg SITELLE cannot observe North of +63.5deg
Airmass limit for ESPaDOnS3.0observations can be performed up to an airmass of 4.0 if needed
Airmass limit for SPIRou2.5recommended limit to ensure the Image Quality remains good

Requested time Please ensure that the time requested in each proposal only includes the time requested from the agency selected (not the total time requested from all agencies concerned).

Please include in the time requested:

  • The integration time required to reach the necessary SNR. Please provide an example of the output of the ETC.
  • The overheads per exposure.
  • Time for on-sky calibrations not performed by CFHT.

Additional instructions for Canadian proposals [Up]

Multi-semester proposals CanTAC can recommend that CFHT schedule observing time for multiple semesters for snapshot or regular programs that require modest time allocations each semester. If you are interested in submitting a multi-semester program, please make a note of it in the Any other expenditure section of your proposal.

Anonymity of Canadian proposals The CanTAC requires that proposals be written in an anonymous fashion. CanTAC may choose to reject proposals they feel do not meet this criteria. Please refer to this article on Cassiopeia for more details and for tips and tricks about how to write anonymous proposals.

The anonymized proposals will consist of the Title, Abstract, Scientific Justification, Technical Justification, Instrument configuration, the list of targets and transit times (if applicable), the references and the link to other proposals. These sections will be given to CanTAC "as is". It is the responsibility of the proposers to ensure that they are written anonymously. Also, please insure that the uploaded pdf files do not include any identifying text in the headers of footers of the file.

The following fields will be removed from the anonymized proposals: PI and list of collaborators, Relevant previous allocations.


Snapshot programs [Up]

All agencies are invited to encourage their community to submit snapshot programs. These programs must be able to accept an Image Quality worse than 1.2" or significant levels of extinction. It is therefore recommended that IQ=1.2" be used and/or that some extinction be included when the Exposure Time Calculators are used. Snapshot programs are used not only during bad weather conditions but also to fill gaps in the queues when no A, B or C program are available or suitable. Snapshot programs are not counted toward an agency's allocation.



Good luck and clear skies!