102nd Meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

16-17 November, 2022, Waimea, Hawaii


After deliberation during its Quarterly Report-III 2022 teleconference, the CFHT Board of Directors, in consultation with the Executive Director, endorse the following SAC recommendations:

Recommendation 1 Evolution of CFHT Capabilities
Recommendation 2 On-sky Priorities of instrumentation Suite
Recommendation 3 Call for Letters of Intent for New Partnerships
Recommendation 4 Development of VISION Project
Recommendation 5 Reallocation of SPICE Nights

Report of the 102nd meeting of the CFHT Scientific Advisory Council,
November, 2022

The 102nd Science Advisory Council meeting was held in a hybrid format (Waimea and online) from November 16-17 2022. SAC members St├ęphane Arnouts (vice-chair), Étienne Artigau, Anthony Boccaletti, Sylvie Cabrit, Eugene Magnier, Alan McConnachie, Laura Parker (chair), Mathias Schultheis, and David Tholen attended the meeting. The CFHT Executive Director Jean-Gabriel Cuby, Director of Engineering Andy Sheinis, Instrumentation Group Manager Kevin Ho, Astronomy Group Manager Nadine Manset, Director of Science Operations Daniel Devost, and MSE System Scientist Jen Sobeck gave presentations and participated in discussions together with other CFHT staff members.

SAC notes that this was our first meeting with Executive Director Jean-Gabriel Cuby and we look forward to working together in the coming years. SAC also wishes to thank Kei Szeto for his many years of service as MSE Project Manager and Project Engineer and wishes him well in his retirement.

SAC would especially like to thank the CFHT executive for arranging a trip to the summit for those of us who could attend. Visiting the telescope and Maunakea leaves a lasting impression for all of us. We would also like to thank the Executive Director for inviting us to meet with Hawaiian Elders in a dialogue after our summit visit. We strongly encourage this kind of engagement going forward.

SAC heard from the Executive Director regarding initiatives that are being explored to foster a culture of understanding and reconciliation with the native Hawaiian community. SAC endorses these initiatives and considers them essential to the future of the Observatory and astronomy on the Big Island.

The Future of CFHT

SAC was informed about the significant change in the management of Maunakea: Act 255 creates the Maunakea Stewardship and Oversight Authority (MKSOA) which will assume responsibility for the management of Maunakea. SAC learned about the impact of this transition to MKSOA on CFHT, astronomy, and the wider Big Island community. Specifically, SAC heard that it is highly unlikely that any new lease negotiations will begin until at least 2028. This development changes significantly possible timelines for the realization of MSE, since it pushes first light to 2040. However, it additionally produces an opportunity to ensure MSE proceeds with meaningful and authentic engagement from the whole Big Island community. The shift in timeline also introduces an opportunity for new instrumentation development and scientific opportunities that can bridge the gap between the existing CFHT instruments and future MSE capabilities.

In this context, SAC was excited to hear from the Observatory about significant new developments in the planning for the next decade of CFHT operations, and congratulates the Observatory on the significant future planning exercise that they have undertaken. SAC agrees with the Observatory that, while the new timeline for MSE is disappointing, it is highly unlikely that any other 10m-class dedicated MOS facility will see first light significantly in advance of the new timeline for MSE. Of course, during this interim period there will be significant opportunities for 4-m class dedicated facilities and 10-m class instrumentation that will undoubtedly lead to new scientific advances. However, given the extensive science case for an MSE-like facility, and the huge number of potential targets that will be identified in the coming years of imaging surveys across the electromagnetic spectrum, SAC believes the scientific promise of MSE as a powerful community-based survey facility remains.

SAC was especially impressed with the integrated, community-driven, approach to the CFHT instrumentation suite that the Observatory is proposing, integrating two of the most successful CFHT instruments - ESPaDOnS and SPIRou - into the dynamic spectroscopic future of CFHT through VISION, augmented with a new IFU capability and a prime-focus based MOS system feeding DESI-like spectrographs. SAC believes that this suite of spectroscopic instruments would provide a compelling "final" instrumentation suite for CFHT prior to its transition to MSE. SAC agrees with the Observatory that the detailed science cases and surveys that this suite of spectrographs will conduct must be driven by the broader community that will build these instruments. SAC recognizes the excellent strategic and scientific opportunities that this instrumentation suite presents, to develop the collaboration, staff, operations, and technical teams that will ultimately enable a much smoother transition to MSE than has previously been envisioned.

RECOMMENDATION #1: SAC strongly endorses the broad vision of the evolution of CFHT capabilities into a dynamic spectroscopic instrumentation suite including VISION, a large format IFU(s), and a multi-object spectroscopic survey instrument, as a scientifically compelling future for CFHT in its own right. SAC additionally recognizes that it represents an excellent transition phase for CFHT as it continues to prepare for a future as MSE, operationally, technically, scientifically, and in terms of partnership. This phase must also include continued community building and design effort for the final MSE facility.

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VISION and the IFU/MOS concept provide complementary capabilities that would broadly serve our communities. This leads SAC to encourage the Observatory to view the proposed "final" instrumentation suite for CFHT as an integrated whole, albeit one that can be phased in time and in funding as required. A phased approach also ensures maximum flexibility for the Observatory in its ongoing evolution. In particular, SAC notes that there is no need to prematurely decommission any of the existing instrumentation. SAC emphasizes that this instrumentation development must be scientifically compelling and schedule-driven.

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RECOMMENDATION #2: SAC recommends that the Observatory prioritize schedule in working towards this instrumentation suite, and that all reasonable steps are taken to ensure new science capabilities appear on-sky at CFHT on short (few years) timescales. Specifically, SAC recommends the following on-sky priorities in order:

  • VISION (modes 1, 2 and 3)
  • a large-format IFU sharing the Cassegrain Bonnette with VISION, feeding a moderate-resolution spectrograph
  • a wide field prime-focus MOS system feeing multiple moderate-resolution spectrographs

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SAC notes that a large format IFU feeding at least one DESI-like spectrograph is achievable at a small fraction of the cost of the whole pathfinder instrument, and that working as part of the VISION system will enable excellent new science capabilities for CFHT while providing important steps to enable the MOS system. Such a system can also be on-sky much faster than the full MOS instrument, providing significant momentum to the whole initiative while enabling fantastic scientific opportunities as it is active during the LSST survey of the Rubin observatory, among other time-domain surveys. This proposed phasing is driven in part by anticipated funding and deployment timescales: we emphasize that the MOS capability is recognized as an essential component of the future of CFHT and the bridge to MSE and must be actively pursued at high priority as a component of the future of CFHT.

RECOMMENDATION #3: SAC recommends that CFHT issue a call for Letters of Intent for new partners to contribute towards creating this dynamic spectroscopic capability for CFHT. The call should lay out the proposed vision for CFHT over the course of the next decade, including laying the pathway for MSE in the future, but also as a self-contained, scientifically compelling future for CFHT in its own right. The Call should coincide with significant engagement of potential collaborators by senior members of CFHT.

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VISION

The VISION project is similar to what was presented at the last SAC meeting in May 2022 with mode 1 (SPIRou alone) and mode 2 (ESPaDOnS alone) being relatively straightforward to implement, with respectively no optics, and a pair of mirrors. In the latter, VISION allows adding a low frequency guiding mechanism for centering the beam on ESPaDOnS. Mode 3 requires more care on the design to preserve throughput, spectral coverage, and polarimetric capabilities. With a small incidence angle (~12°) and +/-5 arcmin alignment precision, the analysis of the Mueller matrix shows that the performance in polarimetry can be met with mode 3 across most of the wavelength range. The dichroic manufacturer CILAS, also identified for the twin project at TBL, is working on the optimization of the dichroics. The mechanical structure has been simulated with the Finite Element Method to ensure that flexures are not degrading the precision of alignment. As a result, a design minimizing the mass of the mode-switching device has been defined. The total no-labour cost is estimated at 152k€, with a proposed cash contribution of CFHT of 98k€ (with 50k€ already allocated) while the rest of the cost (54k€) should be covered by CNRS/INSU and IRAP. The expected FTE contribution from CFHT is 1.2 FTE. SAC considers the level of funding reasonable for the expected scientific return.

Compared to May 2022, the schedule has been delayed by 3 months which still allows the commissioning of modes 1 and 2 to occur optimistically by the end of 2023. Mode 3 is expected to be completed a few months later. SAC notes that even if mode 3 does not meet the polarimetric specifications, its design would still allow for simultaneous high-resolution spectroscopy in the visible and near IR, which would be a powerful asset for time-domain astrophysics for the CFH community.

RECOMMENDATION #4: Strongly supports the development of the VISION project, as a key enhancement of the unique spectro-polarimetric capabilities at CFHT in the next decade. In that context, deploying mode 3 on a short timescale after modes 1 and 2 is critical. SAC encourages a continued close interaction between CFHT and IRAP.

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SPIRou upgrade

SPIRou underwent a major upgrade and opening of the instrument in recent months. The upgrade included the addition of an IR LED that allows for a full detector illumination rather than an illumination through the fiber train. The LED permits the 2D image flat fielding (rather than spectral flat fielding) and characterization of the science array outside of the footprint of orders (e.g., eventual delamination in corners). The SPIRou DRS team is currently exploring the possibility of using the LED to mitigate the impact of persistence between science targets.

An upgraded feedthrough flange with a glycol-cooled plate was added, and thermal background tests are planned. The initial plan included an upgrade of the slicer, but Winlight, the slicer manufacturer, failed to provide a new slicer in time due to manufacturing issues.

The model of SAM card that currently controls SPIRou's H4RG science array is now discontinued and CFHT has spare parts from four partially or not working cards that could be used as spares should the one currently used fail. This adds a significant risk to the long-term maintenance of SPIRou. Given this, it would be prudent to explore the possibility of moving from the SAM to the MACIE controller for the science array. The engineering team is encouraged to contact the UdeM group regarding its experience using MACIE cards on NIRPS.

Following the thermal cycle after the upgrade, it was found that SPIRou was significantly out-of-focus. After optical modeling, and, ultimately, an inspection of the optical bench after warm-up, the problem was traced to a tilt of the parabola caused by failure of a glued supporting puck. The exact reason why the glue failed remains unknown, but the best explanation is that it weakened during the 2018 earthquake and became loose after thermal cycling. The damaged part of the puck was ground, and the supporting parts glued. Inspection of similar pucks elsewhere in SPIRou's optical train showed no other puck failures. Safety brackets were installed to support the parabola and grating should a similar failure happen in the future.

Kealahou

SAC Congratulates the team on a successful deployment of the K1 Proposal Submission Tool for the 2023A call for proposals in August 2022. SAC is also glad to see the successful integration of ESPaDOnS with Kealahou K2, joining SPIRou. The next instrument to be integrated into Kealahou K2 will be SITELLE, expected by the 2023B call for proposals.

When the Kealahou team is done with the integration of the existing instruments, they will move to integrating VISION. The Kealahou infrastructure will be relevant for the future CFHT instruments and eventually MSE.

Operations Updates

The observatory suffered an unscheduled shutdown following a leak in the primary mirror supporting system. The mirror was removed and the leaky support puck was replaced. The rubber seals and related components were replaced for all pucks. The success of this effort is seen in the good image quality in images after the mirror was replaced and the telescope was returned to service. While the mirror was off the telescope for this repair work, it was recoated. SAC congratulates CFHT for the successfully completed primary mirror repair.

WIRCam power supply was upgraded and metallic debris was removed from the cryostat. A sudden warming of the ESPaDOnS detector cryostat was seen and this is hypothethised to originate from a separation of gasses in the PolyCold cooler. Performing a preventive warming and pumping of the cryostat on a quarterly basis should solve this issue.

SAC learned that a series of power failure events damaged a number of servers and unfortunately led to the loss of two nights. SAC appreciates the effort after this extreme event to implement mitigations against such a failure in the future, including reducing dependencies between Waimea and the summit and a reassessment of the power support infrastructure. While this event caused the non-weather downtime to exceed the goal of 2% by a small amount, SAC notes the impressive ability of the observatory to maintain a very low loss of nights to technical failures over the past many years.

SAC was happy to learn that the risk register continues to be a useful tool for tracking maintenance needs at CFHT. We would welcome seeing the current register at each meeting. We also learned during the meeting of a serious incident during mirror recoating and, if not already in place, SAC encourages tracking "near-misses" and the institution of a process to learn from such events.

Large Programs

SAC was pleased to see that the previous generation of LPs all finished at greater than 80% completeness and it is encouraging to see so many CFHT LP-focused papers published and submitted in 2022.

LPs, like all programs, were affected by the extended absence of SPIRou during the upgrade process. UNIONS was not much affected since most of their fields are in A semester, CLASSY received some extra time due to MegaCam being on the telescope for more nights, and SPICE is the most affected since SPIRou was not available for an extended period. One way to help SPICE achieve their science goals during this limited-term LP is to shift some of their 2022B allocation to 2023B. SAC also notes that given the large asymmetry in the semesters for UNIONS observations that the more CLASSY and SPICE observations that can be done in B semesters the better.

RECOMMENDATION #5: SAC recommends reducing the SPICE allocation for 2022B to 30.7 nights (from 45.1) and reallocating those 14.4 nights to 2023B.

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Time Allocation Report

For semester 2022A, weather losses amounted to 18.2 percent of the time, while technical issues amounted to 2.5 percent, somewhat higher than the 2 percent target value, due primarily to a major computer failure. SAC does want to highlight and congratulate CFHT staff for consistently keeping technical losses at a very low level.

Starting with semester 2022B, the time conversion for Megacam changed from 5.5 hr per night to 5.0 hr per night. The unavailability of SPIRou for a scheduled run led to a special call for Megacam proposals to fill five nights.

PI proposals for semester 2023A requested, in descending order of demand, ESPaDOnS, SPIRou, MegaCam, SITELLE, and WIRCam. However, WIRCam remains the most popular instrument for ASIAA and NAOC proposals, while MegaCam is the most requested instrument by UH.

SAC was informed that 2023A is the last semester that GRACES will be on the telescope as the Gemini Observatory wants to reduce the number of instruments it supports. SAC was disappointed to hear this news. Remaining time in the exchange program will need to be used in the next two years.

Grade A and B program completion was fairly uniform in the 62-74 percent range for Canada, France, and Hawaii, with 100 percent for the much smaller NAOC and ASIAA time allocations.

Spirou is about 20 scheduled nights short due to the upgrade taking longer than expected. Other instruments were adequately scheduled.

QSO

QSO continues to be a very efficient observing mode and is well adapted for time-constrained programs. The QSO team is now back to its nominal number of 4 remote observers. SAC is pleased to see that ESPaDOnS is now fully using Kealahou 2.

In 2022A the completion of A programs with SPirou, ESPaDOnS and WIRCAM were above 85%. ESPaDOnS lost 2 nights due to technical issues (power outage in July). SPIRou had a very good run with high completion for PI and SLS programs.

MegaCam and SITELLE were hit by bad weather and poor seeing conditions in 2022A (25%). The SITELLE completion is slightly lower than 71% due to the difficulty in validating long OGs. The almost final report on completion of large programs is 84, 84.9 and 94.6% for CFIS, SIGNALS and SLS respectively.

Seeing analysis

SAC appreciated the seeing analysis presented and looks forward to monitoring this going forward. There is some evidence for an increase in DIMM seeing in last few years, but not above levels seen ~a decade ago. There is a significant (and possibly wavelength dependent) difference in DIMM seeing compared to seeing measured from MegaCam images. SAC encourages further investigation to try and understand these differences as well as how they change in time.

Operational and Development Priorities

  1. Normal Operations
  2. IFU/MOS Spectroscopic Project
  3. VISION
  4. Kealahou

Next SAC Meeting

SAC recommends moving to a model of one in-person meeting a year in Waimea (recommend November meeting) and one online meeting a year, except for years with Users' Meetings, when both SAC meetings should be in person. The justification for this suggestion is that SAC benefits enormously from visiting CFHT in Waimea as well as the summit. Meeting with so many members of staff is of great value. SAC can also engage in community building during their visits. However, the carbon footprint of flying many astronomers together for a 2-day meeting is significant and we suggest this compromise solution.

The dates of the next SAC meeting are to be determined.

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