Canada France Hawaii Telescope

Report of the 108th meeting of the CFHT Scientific Advisory Council,
December 2025

The 108th Science Advisory Council meeting was held in Waimea in hybrid mode on Dec 1st-3rd 2025. SAC members Stéphane Arnouts (chair), Scott Chapman (vice-chair), Philippe Mathias, Mathias Schultheis, David Tholen all attended the meeting in person, with Isabelle Boisse (partial time), Ken Chambers, Ting Li and Alan McConnachie attending remotely. Ryan Cloutier was absent on paternity leave. The CFHT Executive Director Jean-Gabriel Cuby, the Director of Engineering Kevin Ho, and the Director of Science Operations, Nadine Manset all gave presentations and participated in discussions.

Kara Dumaguin was introduced as the new CFHT Director of Community Relations. SAC welcomes her to this important role at CFHT and looks forward to working with her in the future. We thank Kara for leading the attendees of the meetings in a Kilo Circle, which was a wonderful way to begin the meeting.

The SAC would like to provide special recognition to Kevin Ho upon his imminent retirement, after more than two decades of service to CFHT. Kevin has been a lynchpin in the continued success of CFHT, both from a technical, engineering perspective as well as from a leadership perspective. He will be missed and the SAC hopes he has a very well-deserved retirement.

Report from the Executive Director

The Executive Director began with an extensive summary of high-level activities ongoing at CFHT over the past year. This included an extensive discussion of ongoing internal organizational and communication challenges that are being proactively addressed. The SAC thanks Jean-Gabriel for this open discussion and welcomes the efforts by all parties within CFHT to improve organization, communications and create a positive working environment and culture for all staff members.

SAC also heard about the ongoing engagement of potential new collaborators and partners in CFHT. In particular, SAC welcomes the news of ongoing discussions with potentially major collaborators with interests in CFHT over the coming years and encourages these efforts to continue. It was noted that among these possibilities, there is potential interest in the use of WIRCam, which is due to be decommissioned, along with SITELLE, at the end of 2026B. SAC heard about CFHT's plans to keep WIRCam cold once it is decommissioned, in an attempt to prevent degradation of its detectors with time or with cycling. Finally, SAC heard about the continued degradation in the MegaCam zero points and the likely contributors from condensation events. In addition to further exploring the throughput degradation which especially affects MegaCam blue filters, the SAC heard how important MegaCam will be for community surveys in the coming decade. Other factors may begin to affect the performance of MegaCam given its age and should be addressed with urgency if they arise.

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In order to manage and standardize the processes for engagement with potential new partners, the SAC was pleased to hear about the creation of the Telescope Access Sub Committee (TASC) at the Board level.

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The Executive Director also informed the SAC about advances in the establishment of the Maunakea Management Plan by the Maunakea Stewardship and Oversight Authority (MKSOA). Specifically, Kua o Wākea is the team of consultants contracted by MKSOA to develop its Management Plan, led by SSFM Consulting, DTL Foundation, and the Edith Kanaka̒ole Foundation, with additional support from Mahina Paishon Consulting, Kōnane Law, Ho̒opili Hou Research Group, and Āina Archaeology. The project schedule calls for the management plan to be published in the last quarter of 2026. Kua o Wākea will organize 10 community workshops across the Hawai'i Islands in early 2026 and will organize specific discussions with the Maunakea Observatories (MKOs). This will include surveys of the MKOs and direct discussions with Kua o Wākea.

The SAC wants to take this opportunity to applaud the efforts of CFHT, its Executive, staff and broader community, in their ongoing leadership in Hawai'i towards a community-based model for astronomy. The path to such fundamental change is slow, but the trends over the last decade have been positive and are being reflected even in the larger international astronomical community that is privileged to use the telescopes situated on Maunakea. There is much work still to do, but these trends point to constructive changes in the international astronomy community that are necessary to help realize a community-based model for astronomy on Maunakea.

We note that in the Canadian Long Range Plan 2020, the first and primary recommendation of the report is ̏We recommend that the Canadian astronomical community (e.g., ACURA, CASCA and NRC-HAA) work together with indigenous representatives and other relevant communities to develop and adopt a comprehensive set of guiding principles for the locations of astronomy facilities and associated infrastructure in which Canada participates. These principles should be centered on consent from the Indigenous Peoples and traditional title holders who would be affected by any astronomy project.̏ In the recent French Prospective, published by INSU, there are a series of recommendations centered around empowering the local communities where French astronomical facilities are located. This includes ̏[involving] local populations in governance and open up infrastructures to mixed uses ̏ as well as ̏ [introducing] awareness-raising initiatives for users and ensure that funding applications include an assessment of societal impacts,̏ ̏ [including] human science courses in science master's programs, for example, to develop the associated vocabulary and raise awareness ̏. Such recommendations are unprecedented in these national reports, and while these recommendations are clearly only a first step, they are an encouraging indication of the increasing awareness of these issues within the international astronomical communities.

There are numerous other examples of this change in the tide. Increasingly, scientific papers being published based on CFHT data or data from other MKOs now include acknowledgements of the privileged location of the observatories on which this science is based. Presentations by scientists using CFHT data, including from some of the largest observing programs, now routinely have a slide or more about the Maunakea and the cultural importance of the Mauna. At the 2023 Euclid science consortium meeting, a major and prominent space mission that uses in part data from Maunakea, a dedicated presentation exposed a large number of European-based astronomers to many of the issues being discussed in Hawaii. While all of these are small changes, such activities would have been unheard of 10 or more years ago. The SAC believes these are happening because of increased awareness of these issues internationally, and the SAC is hopeful that these trends continue and they will continue to encourage their communities in this regard. Propositions that could be taken from the agencies to improve the engagement of CFHT with the local community must be encouraged.

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Wenaokeao AIT-V scheduled

Wenaokeao will be delivered in June 2026 (with a small schedule contingency), within a fully operational dual-PM structure (IRAP-CFHT) and with secured funding from CNRS-INSU. Note that extra costs for fees should be considered. Luc Arnold (Astronomer, CFHT) has been assigned as Project Scientist. Critical elements, such as the beam splitter structure, dichroics, and optics, have been delivered to IRAP, while the remaining missing parts are not on the critical path. AIT-V preparations are split between IRAP and CFHT, with tools and test plans finalized. Key CFHT hardware (handling cart, broadband artificial star) is scheduled for completion in early 2026. Commissioning for all three modes in scripted engineering mode is scheduled for Q4 2026 (modes 1 and 2 available in 2027A), and Wenaokeao QSO observations are planned to begin in 2027B.

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Kealahou Report

Projects show substantial progress:

• MegaCam SNR Mode development was completed for the 25B semester. The different modes have been fully tested and are already available.
• The K2 User Collaboration Tool, inspired by the K1 tool but with additional access options, is now completed.
• Kealahou-AEON integration began in August 2025, with the full Kealahou API specification for public use expected by fall 2027. The initial AEON Call for Proposals should be ready for the 26B semester, depending on inclusion in the LCO/AEON network.
• Wenaokeao integration work will intensify from now on, with final verifications planned for June to August 2027 for QSO use in the 27B semester.
• Database software: An ongoing upgrade of the Java version (from V8 to V21) is in progress, though it has lower priority than Wenaokeao and AEON+.

Other developments include additional K2 functionalities (target list uploads, entity duplication), inclusion of a slew path safeguard, general user bug fixes and system support. Such developments should also include the LP aspect such as the K2 API for the targets upload.

The SAC commends the Kealahou team, on behalf of the CFHT user community, on their continuous efforts to expand the successful Kealahou platform, a critical component of the CFHT operations. The SAC also encourages the team in their ongoing work on the Wenaokea modes and AEON.

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MKAM Seeing Trends

At the 2022 CFHT Users Meeting, the CFIS PI reported an apparent increase in seeing as measured in MegaCam images. Since 2009, the MKAM DIMM has provided seeing data, primarily near the zenith. Over the period from 2010A to 2024B, the more than 10^6 collected measurements do not show a systematic increase over the past 15 years. No direct coeval comparison between MegaCam image quality measurements and MKAM DIMM seeing measurements was presented this time, due to long-term maintenance of MKAM DIMM. New results should be available for the next SAC meeting.

Discussion of a yearly Call for Proposals

Like many observatories, CFHT issues one call for proposals per semester. However, all space observatories, as well as major ground-based observatories, such as ESO and ALMA, have transitioned to a yearly call, covering a one-year observation period. This longer cycle has several advantages e.g., it avoids repetitive proposals from semester to semester, it saves time for TAC members, it reduces right ascension (RA) pressure, etc. And it is particularly relevant in the context of the Community Survey, which will reduce the number of nights available for regular PI programs.

However, for time-sensitive observations (especially in the context of PhD projects), a fast-track submission process could be introduced on a quarterly basis.

A potential challenge is the compatibility of Kealahou and databases with annual operations. This proposal would apply only to Canada and France, as the University of Hawai?i follows a different process.

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CFHT - ASIAA Partnership

The SAC heard about the conclusion of the partnership between CFHT and ASIAA. The SAC acknowledges this strong and successful partnership running since 2001. This partnership has provided Taiwan ̓ s astronomy community with regular access to all CFHT instruments and valuable observing time, leading to a steady stream of scientific publications and strong participation in several CFHT Large Programs. Over the years, the collaboration has also played a pivotal role in building ASIAA ̓s instrumentation capabilities through joint work on WIRCam, Flyeyes, dome-venting studies, and SPIRou subsystems. In parallel, CFHT has benefited from ASIAA ̓s technical contributions, scientific engagement, and continued investment in the partnership. Overall, the collaboration has been mutually beneficial, strengthening ASIAA ̓s scientific and engineering capacity while contributing meaningfully to CFHT ̓s instrumentation and scientific research.

SAC Mandate and Rules of Procedure

The SAC reviewed member engagement in relation to its mandate and rules of procedure, both of which required clarification. The SAC emphasized the importance of holding the December meeting in person at CFHT headquarters, as this enables SAC members to gain a deeper understanding of the CFHT ̓s facilities - its summit infrastructure, staff, operations, and more - while supporting the effective functioning of the SAC and fostering meaningful exchanges between SAC members and CFHT staff. The terms of reference were also discussed.

The SAC agreed on the following points:

• In-person participation at the December meeting is strongly recommended, with Zoom attendance permitted only under exceptional circumstances.
• Members attending via Zoom are expected to participate in the full session of the meeting each day.
• The SAC will prepare a formal ̏ Mandate and Rules of Procedure ̏ letter for all members. This document will outline member duties, SAC operations, the fixed scheduling window for meetings, quorum requirements including agency representation, conflict-of-interest guidelines, the code of conduct, and expectations for member engagement. Whence approved by the Board and agencies, the SAC recommends that each member sign this letter before beginning their mandate.

CFHT Operations

MegaCam u-band zeropoint

The SAC remains concerned about the decline in u-band throughput, which has dropped by roughly 0.35 mag every three years since 2011 - a trend not seen before that date. MegaCam ̓s blue sensitivity is pivotal for the forthcoming Community Survey where the blue sensitivity of MegaCam is a major interest. The zero-point loss will significantly increase the duration of the survey.

CFH has now ruled out Sulfur dioxide from the volcano as being a primary contributor, alleviating the concern from the last SAC report. The SAC heard that CFH has identified condensation events on M1 as being at least partially related to the throughput degradation seen with MegaCam. However, CFH highlighted that this is not the entire story, as degradation continues gradually after the sharp drops associated with specific condensation events.

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SPIRou

No operational issues.

ESPaDOnS

No operational issues.

Sitelle

The SAC supports efforts to relocate the SITELLE instrument so that it remains a productive science tool.

MKAM

The SAC appreciates the repair and maintenance of the Maunakea Atmospheric Monitor and looks forward to Gemini's RING instrument replacing this capability in the future.

SVOM

The SAC is happy to see the installation of the 2nd VHF antenna as part of the SVOM alert network.

Bridge crane VFD/EStop upgrade

The SAC appreciates the progress on the Variable Frequency Drive and looks forward to the implementation.

Freight elevator

The SAC congratulates the team on the repair of the Freight Elevator.

Dome and Enclosure

The SAC appreciates the progress on procurement and of the dome bogie wheels and planning for other deferred dome enclosure repairs.

Cyber security

The SAC appreciates this concern and assumes it will continue to be tracked and rated in the risk register.

Safety

The SAC looks favorably on the progress of outsourcing the Safety oversight to the contractor Lawson & Associates.

Deferred Maintenance

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Risk Register

The SAC did not review the detailed Risk Register at this meeting. This is a critical and useful tool for planning and SAC will review it in detail at the May 2026 meeting.

Science Operations

QSO report for semester 25A

All five instruments were scheduled during semester 2025A in the following amounts: SPIRou (494 hr.), MegaCam (353 hr.), SITELLE (82.1 hr.), WIRCam (48.2 hr.), and ESPaDOnS (29.7 hr.). Completion of A- and B-ranked programs was 90 percent. C-ranked programs were executed at the equivalent of 6 percent of the validated time for A- and B-ranked programs, to fill gaps in RA without suitable targets from the A- and B-ranked programs.

Of the 1805 total hours available, 245 hours were lost to weather or high particle counts following a Kilauea eruption, 23 hours were lost to technical problems, and 8.5 hours were used for engineering. The 14 percent of time lost to weather is better than the 25 percent expected.

Programs utilizing SPIRou benefited from a higher completion level, leading to the following agency balance values (time allocated to A- and B-ranked programs, time validated for A-and B-ranked program, and percentage): Taiwan (6.9, 6.9, 100%), China (39.9, 39.1, 98%), France (114.8, 94.5, 82%), Hawaii (128.3, 97.1, 76%), and Canada (124.2, 85.1, 69%). The lower completion percentage for Canada is due to less utilization of SPIRou.

There were 14 accepted proposals in 2025A for Director's Discretionary Time, totaling 10.3 nights. Megacam was used on 4 nights, SPIRou on 3.7 nights, SITELLE on 2.2 nights, and WIRCam on 0.5 night.

Time allocation report for 25B

The time allocated to PI programs for NRC, CNRS, and UH contribute 42.5%, 42.5%, and 15% of their time, respectively. NRC and CNRS provide an equal number of nights to the Large Programs. During semester 25B, CFHT performed the primary mirror recoating, which resulted in a shutdown of 9 days. For that reason, 5 additional engineering nights were allocated in 25B.

Phase 1 result report for 26A

For semester 2026A, in total 71 proposals have been submitted with 24 proposals for NRC, 22 proposals for CNRS, 14 proposals for NAOC and 11 proposals for UH. The pressure rate for NRC and CNRS is about 3, for NAOC is about 2, and for UH is about 1.

The demand for SPIRou and SITELLE is higher than that for MegaCam, while the demand for WIRCam remains low.

Large Programs

Ending LPs

• Unions:

  UNIONS is a Large Program to accompany the EUCLID mission to achieve its weak lensing measurements and to compute reliable photometric red shifts essential for the PSF calibration of the VIS instrument in Euclid. UNIONS is building towards a major internal release. All the imaging acquired from all 3 telescopes (CFHT/Subaru/Pan-STARRS) has been processed, calibrated and stacked. A so-called "Grand Unified Catalog" is in production, with completion expected shortly where the first public data release will be available to the larger astronomical community. No technical issues have been reported. To date, UNIONS has achieved 69% completeness. Some difficulties have been reported when using K2 for large target lists.



• CLASSY:

  CLASSY is a Large Program (LP) with a total of 370 hours allocated (including a 90-hour extension), dedicated to the detection and orbital characterization of Trans-Neptunian Objects (TNOs). The discovery rate and depth are approximately 150 objects per pointing. A dedicated reduction pipeline has been developed, enabling numerous by-product projects from the observations. However, the CLASSY team feels that, due to competition with UNIONS, they lack the capacity to take on the significant workload required to integrate the Solar System observing program into the Community Survey. In Semester 2025A, 30 hours were allocated and fully observed. To date, CLASSY has achieved 83% completeness, with 5 out of 6 blocks completed, surpassing the minimum requirement of 80%.



New LPs

• PLANETS:

  PLANETS is a Large Program (LP) with a total of 1680 hours allocated, dedicated to the physics of exoplanets using SPIRou. It is divided into four Work Packages: WP1 (Blind planet search), WP2 (Follow-up of transiting planets), WP3 (Magnetic stars and planet formation), and WP4 (Exoplanet atmospheres). As a monitoring program, PLANETS requires 90% completion of the planned visits for each target. For Semester 2025A, 420 hours were allocated, of which nearly 95% were observed and validated. The same number of hours was allocated for Semester 2025B, and by mid-October, nearly 60% had already been completed. In both the 2025A and 2025B reports, the PLANETS team highlighted the challenge of the window function due to bright/dark time alternation. However, pressure on MegaCam makes it unlikely that SPIRou can be used during dark time. The PLANETS team also emphasizes the necessity of regular visits and requests advance notice of any schedule changes. Note that target lists could also be improved with an appropriate API.



• UNIONS+:

  UNIONS+ is the extension to DEC 15 to 30 of CFIS-UNIONS, the MegaCam u and r band components of UNIONS (along g,i,z on Pan-STARRS and Subaru-HSC), supporting Euclid in particular. This extension connects the original UNIONS area with LSST over the north galactic cap Euclid coverage. UNIONS+ has achieved 38% completeness.



• PRISTINE:

  PRISTINE is a large program that began its observation in August 2025. Its objective is to observe or re-observe with MegaCam the Milky Way in order to search for the oldest stars of the galaxy through the Ca H&K filter (or to gather the age of the others through the same indicator). It is partly the continuation of the Pristine programs that run as snapshots programs since 2015, and a follow-up in the context of the WEAVE multi-object spectroscopic survey.

  This LP was allocated 50h this semester (of a total of 167.4h), with a completeness of 83.8% in the current semester. The team acknowledges the dedication of the CFHT queue team but note that it would be helpful for all to be able to upload a large list of targets.




Recommendation #10: SAC recognizes the importance of completing the ongoing Large Programs before 2027. SAC recommends prioritizing UNIONS+ over the C+F PI programs for the 26A and 26B semesters.

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Community Survey and CSWG Updates

During the meeting, SAC received an update from the Community Survey Working Group (CSWG) on its activities to date, including seven telecons between July and October devoted to refining the Call for Proposals, the LOI process, and the overall timeline. SAC acknowledges and greatly appreciates the substantial effort that the CSWG has invested in organizing the community survey process. SAC was pleased to see the strong community response to the LOI call, with seven LOIs submitted (six for MegaCam and one for Wenaokeao, with one additional MegaCam LOI pending). The Wenaokeao LOI clearly demonstrates that a coherent community has already formed around Wenaokeao science for the Community Survey, while on the MegaCam side the landscape remains more fragmented. SAC reiterates that the overarching goal of the Community Survey is to reflect the community̍'s scientific interests as broadly as possible and to deliver high legacy value.

To ensure effective coordination, SAC agreed that the CSWG should have a clearly identified Chair from SAC. Ting Li has agreed to serve in this role. SAC recognizes Ting̍'s strong engagement in the CSWG over the past six months and SAC has full confidence in her ability to carry out the role with professionalism. To support her in these responsibilities, SAC also recommends appointing a Vice-Chair who can step in whenever the Chair determines it would be inappropriate to lead particular discussions or decisions.

Over the next five months, prior to the Community Survey proposal deadline (April 30, 2026), the overall charge remains the same as described in the May 2025 SAC report. In addition, the CSWG is charged with the following near-term tasks:

• Use the submitted LOIs (six MegaCam, one Wenaokeao) to encourage communication among teams and help consolidate them into coherent, community-wide survey concepts, particularly on the MegaCam side.
• Send a short questionnaire to all LOI PIs in mid-December to collect key survey details (filters, seeing requirements, observing strategy, footprint/coverage, etc.) and to obtain permission to share their LOIs and questionnaire responses publicly. The PIs are encouraged to answer the questionnaire by Jan 10, 2026, so this information can be posted on the CFHT website ahead of a town hall.
• Organize a town hall in mid-late January to promote open discussion of proposed survey ideas and possible synergies.
• Assist all interested parties in preparing their Community Survey proposals, while not ranking, pre-selecting, or evaluating proposals before the formal submission deadline.
• Continue the development of the peer review evaluation criteria and process and develop an outline for the post-submission process for the CSWGs.



The SAC stresses that the role of the CSWG at this stage is to encourage and enable proposal submissions in line with the SAC expectations described in the May 2025 report.

The CSWG is not responsible for the submission of any proposals, which remain the responsibility of the relevant science teams.

Discussions at SAC also highlighted several structural issues that require clear guidance from the Board and close coordination between CFHT, SAC, TASC, and the CSWG. In particular, SAC identified the need for a transparent process by which non-CFH partners can participate in the Community Survey (for example, as co-Is on the main proposals), and for well-defined rules governing membership, data access, and proprietary periods. These questions are closely linked to ongoing and potential associate partnerships and to the broader strategic direction being developed by the Board and TASC. SAC therefore believes that early and direct involvement of Board representatives in the CSWG will be essential to ensure that the emerging survey designs remain aligned with the Board̍'s expectations and constraints.

Recommendation #11: The CFHT SAC and Board, including the new TASC, should immediately define a process whereby non-CFH partners are able to participate in the upcoming Community Survey. SAC will communicate this process to the CSWG and the teams currently drafting proposals.

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Recommendation #12: Given the importance of membership and data-access policies for the Community Survey, the SAC recommends appointing one Board member from each of the Canadian and French agencies to the CSWG. These representatives would reflect the Board̍'s interests and provide guidance on policy and governance questions that arise during the community survey process.

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Operational and Development Priorities

• Normal Operation


• Wenaokeao


• Deferred maintenance & risk mitigation


• Kealahou (prioritized as Wenaokeao Mode 1-3 / AEON)



9. Next SAC Meetings

The next SAC meeting will be held remotely in May, from Tuesday, the 19th, to Thursday, the 21st. For the November SAC meeting, two weeks are proposed: Nov 16-20 and Nov 30 - Dec 4.




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