Call for 2025A - 2026B CFHT Large Programs

As proposed in its 10-year plan, CFHT is opening up to 400 nights for Large Programs to be executed over a maximum of 1.5 years for MegaCam, and a maximum of 2 years for ESPaDOnS and SPIRou. This new round of Large Programs will be followed by a Community Survey (similar to the very successful CFHT Legacy Survey - CFHTLS). Details regarding this Community Survey will be developed in the coming year.

NRC (Canada) and CNRS (France) are offering up to 70% of their agency time for this round of Large Programs.

Details of the 10-year plan were presented in the fall of 2023 during a Community Consultation process. Slides are available.

1. Required Non-binding Letters of Intent Due March 1st, 2024

Interested teams must submit a "Letter of Intent to Submit a CFHT Large Program Proposal" before March 1st 23:59 UT, by sending an email (plain text or PDF file) to the Executive Director . An acknowledgment that a submission has been received will be sent within 2 business days.

Instructions regarding the content of the LoI are available online.

Only Principal Investigators (PI) who submitted a Letter of Intent can submit a proposal for a Large Program.

2. Large Program Definition

A Large Program (LP) shall request a minimum of 50 nights total, on MegaCam, ESPaDOnS, or SPIRou. More than one instrument can be requested in the same proposal.

SITELLE and WIRCam are not offered.

VISION is an optomechanical interface that will allow installing SPIRou and ESPaDOnS at the Cassegrain focus of the telescope at the same time. Mode 1 is equivalent to using SPIRou without any additional optics. VISION Mode 2 is equivalent to using ESPaDOnS, with additional optics (mirrors and doublets). Both Mode 1 and 2 will be commissioned in late 2024. VISION Mode 3 (simultaneous ESPaDOnS and SPIRou observations) is not offered for this call for Large Programs. A Large Program may be carried with VISION Mode 1 or Mode 2 once VISION will have been fully tested, commissioned, and released for our regular operations. Teams who plan to request ESPaDOnS are encouraged to read additional details about VISION below.

Before submitting a proposal that includes a new MegaCam filter or a new functionality on any of the instruments, a team should contact the Director of Science Operations

A Large Program may include 2 or more medium-size work packages or programs with different science goals.

A MegaCam Large Program shall only request time during semesters 25B, 26A, and/or 26B. This is to allow time for the completion of the UNIONS Large Program in 25A.

An ESPaDOnS or SPIRou Large Program may request time during any of the 4 semesters 25A to 26B.

3. Time Available

Up to 400 nights over 2 years are available.

Teams must take into account that MegaCam is scheduled during dark time (Moon illumination less than 50%), up to a maximum of ~90 nights per semester. ESPaDOnS and SPIRou are typically scheduled during bright time (Moon illumination more than 50%), up to a maximum of ~90 nights per semester; these instruments may also be scheduled during grey or dark time if the pressure requires it.

MegaCam observations typically start and end at the 12-degree twilights. SPIRou and ESPaDOnS observations typically start and end at the 8-degree twilights. Any plan to deviate from those practices (e.g. only starting MegaCam observations later than the 12-degree twilight, at the 18-degree twilight) must be mentioned in the proposal.

A shutdown of SPIRou will occur during the LP period, for up to 8 weeks, to perform maintenance on its cryogenic system. The primary mirror of the telescope will also be recoated in mid-2025 or mid-2026. Any potential or anticipated impact from those technical activities yet to be scheduled on the execution of an LP must be mentioned in the proposal.

Proposals have to use the following conversion for the number of hours per night for each instrument:

  • MegaCam: 5.0 hours/night
  • ESPaDOnS: 7.5 hours/night
  • SPIRou: 7 hours/night

These numbers correspond to averages over the full range of observing conditions and right ascension. While the time requested in a proposal is in hours, the final allocation of an accepted LP will be in nights, in order to absorb any variations of the observing efficiency.

4. Instruments Offered

Teams are encouraged to read the documentation related to the instrument(s) they plan to use. Exposure Time Calculators are also available and must be used to calculate the number of hours requested.

Instrument Webpage ETC Instrument Scientist
MegaCam MegaCam DIET Heather Flewelling
ESPaDOnS ESPaDOnS ETC Nadine Manset
SPIRou SPIRou ETC Luc Arnold

5. QSO Mode and QSO SNR Mode

All Large Programs will be executed under the QSO mode. In addition, it is assumed that a LP will take advantage of the QSO SNR mode. If the QSO SNR mode is not suitable, the team must justify it in their proposal.

For scheduling purposes, Large Programs are considered as a separate Agency at CFHT. The amount of time allocated each semester is split into A (higher) and B (lower) priority time along the ratio 40%(A) and 60%(B), and LP observations will be carried out with the same A/B observing priority policy as is applied to all other Agencies. This arrangement spreads the risk associated with weather and telescope problems equally between regular and Large Programs.

6. Large Program Completion Policy

LP time allocations are not carried forward from one semester to the next. A Large Program completion policy is in place (and nights are reserved for this) to help attain at least 80% completeness of approved LPs in the case of exceptionally adverse circumstances when science warrants its application.

7. Proprietary Periods

For the participating communities (i.e., attached to the agencies allocating observing time to the LP), the default is immediate access to the data through the CADC. The PI may propose to retain the usual one-year proprietary period for participating community access (or any other period not to exceed one year after the end of the last semester during which observations were obtained, as is the case for any PI program).

For access by anyone else, the default is the standard one-year proprietary period after the end of each semester for the duration of the LP. The PI may request, with justification, that world access be denied for an extended period not to exceed one year after the end of the last semester during which observations were obtained.

For the metadata information (e.g., target name and coordinates), the default is to release the Exposure Metadata immediately to CADC where it is published on the web. The PI may request, with justification, a delay in exposing the Exposure Metadata at CADC.

8. Multi-agency Proposals

Teams that intend to submit a joint proposal between two or more Agencies or partner communities are required to distribute the total amount of hours requested among the participants. This distribution should be made according to the relative scientific contribution from each community in the collaborative team; it is up to each team to determine this distribution. This distribution must be included in the proposal. The National TAC of any named community will be given that proposal and asked to comment on the scientific value and confirm their agreement to contribute the time requested to the Large Program agency.

9. VISION Considerations for ESPaDOnS Proposals

VISION Mode 1 is equivalent to using SPIRou without any additional optics. VISION Mode 2 is equivalent to using ESPaDOnS, with additional optics (mirrors and doublets).

VISION requirements state that the maximum acceptable level of polarimetric contamination / crosstalk induced by VISION shall be:

  • from Stokes I (unpolarized) to Stokes Q, U and V (linearly and circularly polarized light) spectra: 0.01%;
  • from Stokes Q and U to Stokes V spectra (and vice versa): 1% (as typical Stokes QUV signatures in spectral lines very rarely exceed amplitudes of 1%);
  • from Stokes Q to U (or vice versa), crosstalks are not an issue if within 10%, and can be compensated for by a small rotation of the instrument and / or through the observation of standard stars.

If a team proposing an ESPaDOnS program has concerns regarding the performance of VISION Mode 2, they shall provide details of those concerns and the appropriate levels of contamination or crosstalk acceptable.

10. Data and Project Management Plan

The proposal shall include a Data and Project Management Plan that includes information or requirements affecting CFHT, work to be performed by the LP team, and availability of value-added data products.

Information or requirements affecting CFHT may include real-time analysis requirements.

Details of the work to be performed by the LP team may include a data-analysis plan, a description of available resources, details showing the capability of the team to handle the data reduction, proposed proprietary periods, proposed metadata release proprietary periods, or other considerations regarding the propriety of the data or targets.

The Large Programs Time Allocation Committee (LPTAC) will look favorably upon a proposal that includes the timely public distribution of value-added products (advanced data products) such as processed data calibrated with the best tools possible, catalogs, and databases.

Teams are strongly encouraged to contact JJ Kavelaars and explore collaborations with CADC and CANFAR.

Any potential collaboration with CADC or CANFAR, or another data center must be mentioned in the proposal.

11. Support Offered to the QSO Team by LP Teams

CFHT is asking teams to indicate if they intend to support CFHT's operations and observations, and what level of resources they are committed to providing. Operations support and assistance can take many forms, including, but not limited to, the following:

  • Keep constantly updated accounting of Large Programs execution, in formats to be agreed with CFHT staff (e.g., website or private wiki with a table).
  • Provide daily (during runs when Large Programs are scheduled) and at a time of the day agreed by CFHT staff a list of observation groups to be inserted directly into QSO queues, with priorities; this is especially relevant for LP that monitor targets over time.
  • Provide on-site scientific personnel, on a part-time or full-time basis, to assist in the execution of Large Programs, and/or scientific operations at CFHT (data reduction, queue coordination). Limited CFHT funds are available to cover the cost of plane tickets, visa, and for lodging assistance for students or visitors willing to stay 6-12 months on site.

12. Additional Technical Details

The total time requested must include overheads:

  • For MegaCam, the overheads are 40s per exposure.
  • For ESPaDOnS, the overheads depend on the readout speed selected for each exposure: fast (20 sec), normal (20 sec), slow (33 sec).
  • For SPIRou, the overheads are 28s per exposure in spectroscopic mode, or 35s per exposure in polarimetric mode.

The total requested time must include the integration time as calculated by the proper ETC, overheads, and any calibration not already taken by the QSO Team. For all instruments, appropriate instrumental calibrations are obtained (biases, darks, twilight flats, lamp exposures, fringe frames). Broad-band photometric standard stars and astrometric standard fields are also taken for the imagers; no spectrophotometric standards are taken with ESPaDOnS or SPIRou. Narrow-band calibrations (for the imagers) must be included by PIs in their proposal and PH2.

Please take into account the following operational constraints:

ParameterLimit or constraintNote
MegaCam observationsbetween 12deg twilightsplease mention if observations need to wait for the 18deg twilight
ESPaDOnS and SPIRou observationsbetween 8deg twilights
Hour angle limits+/- 5h30
Airmass limit for MegaCam2.7622deg elevation limit
Airmass limit for SPIRou2.5recommended limit to ensure the Image Quality remains good

In the case of a MegaCam program please specify if the LSB mode of observing will be used.

An estimate of the number of transits per year must be given together with the likelihood of completion based on weather statistics and bright/dark time available.

Proposals performing monitoring should provide (1) the number of iterations requested per semester and in total, (2) the cadence (period) of the observations, and (3) any other monitoring constraints.

Any program with scheduling constraints should explicitly state (1) if there is a desired minimum length for the observing runs; (2) if there is a need to have observations on consecutive nights; (3) if there are requirements for the minimum number of runs per semester; (4) if there is a need for observations to be taken over more than 2 consecutive hours (e.g. for transits); (5) if there is a need for a moon phase not normally scheduled for the required instrument (e.g., for observations at a given date where the instrument would not normally be available because of the Moon phase.)

13. Content of a Large Program Proposal

The proposals must contain:

  • A scientific Justification: up to 5 pages + 3 pages of figures. References are included in a separate section and do not count toward the 5 + 3 pages limit.
  • A technical Justification (up to 8 pages) that must include:
    • Details about the calculation of the exposure time accompanied by the log of the ETC for each target or for a representative set of targets.
    • An observing plan for all semesters.
    • A discussion of the program's robustness to a reduced data acquisition rate or to evolving instrumental performance.
    • A Data and Project Management plan
    • Tables showing the distribution of time among semesters and agencies.
  • Any relevant additional information described above.

14. Submission Deadline May 1st, 2024

Proposals must be prepared and submitted via the tool kealahou K1. A Tutorial for K1 is available online.

The deadline for submission is May 1st, 2024, 23:59 UT.

15. Selection Process

CFHT will provide to the LPTAC the proposals' technical evaluation reviews including feasibility estimates under normal conditions for each proposed LP.

The LPTAC will rank all proposals after considering:

  • The scientific merit of the proposals.
  • The feasibility of the observations at CFHT.
  • The data and project management plans.
  • The resources and support a team proposes to assist CFHT.
  • The risks associated with incomplete data collection.
  • The willingness of the LP team to provide immediate data access to the participating communities or the whole CFHT community.
  • The willingness of the LP team to provide in a timely manner value-added products via CADC or another data center.
  • The potential use for the data beyond the main scientific goals of the LP.
  • The potential legacy value of the data acquired.
  • The inter-agency nature of the LP team.

In addition to ranking all proposals, the LPTAC reserves the right to reduce or shift nights from one semester to another, compared to what is proposed in the proposal, if it optimizes the use of the nights and helps CFHT's operations.

16. Timeline

After the deadline, proposals will be sent to external referees for a scientific assessment and to CFHT Resident Astronomers for a technical evaluation. By the end of August, the Large Program Time Allocation Committee will transmit their rankings to each National TAC for review and approval. In October, SAC will make the final selection. The SAC also reserves the right to reduce or shift nights from one semester to another, compared to what is proposed in the proposal, if it optimizes the use of the nights and helps CFHT's operations. The SAC will transmit their decision for Board approval.

The selected Large Programs will be created at the end of November, in time for opening Kealahou K2 for semester 25A, for all 3 instruments.

17. Contact Information

Please email questions to the Director of Science Operations .