104th Meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

5-6 Dec, 2023, held in Waimea, HI


After deliberation during the Board of Director's December 2023 meeting, the CFHT Board of Directors, in consultation with the Executive Director, endorse the following SAC recommendations:

Recommendation 1 Support for Implementing VISION
Recommendation 2 Development of IFU Science Case
Recommendation 3 Scientific Evolution of CFHT
Recommendation 4 Decommissioning of WIRCam and SITELLE
Recommendation 5 New LP Call for Programs
Recommendation 6 User Survey Summary
Recommendation 7 Risk Register
Recommendation 8 Complete Current LPs by 2024B
Recommendation 9 Publication Impact Statistics

The Board acknowledges the very clear and insightful SAC report, and thanks Dr. Laura Parker for her service as SAC Chair.

Report of the 104th meeting of the CFHT Scientific Advisory Council, December 2023

The 104th Science Advisory Council meeting was held in Waimea December 5-6 2023. SAC members Stéphane Arnouts (vice-chair), Étienne Artigau (remote), Isabelle Boisse (remote), Ken Chambers, Ting Li, Philippe Mathias, Alan McConnachie, Laura Parker (chair), Mathias Schultheis and David Tholen attended the meeting. The CFHT Executive Director Jean-Gabriel Cuby, Director of Maunakea Spectroscopic Explorer Programs Andy Sheinis, Director of Operations and Astronomy Group Manager Nadine Manset, and Director of Engineering Kevin Ho gave presentations and participated in discussions together with other CFHT staff members. SAC appreciated having so many staff present during the open sessions who could describe ongoing work and answer our questions. Note SAC chair Laura Parker is cycling off SAC and Stéphane Arnouts will become the new chair as of January 1, 2024.

With ongoing budget constraints and uncertainty around the future of astronomy on Maunakea, now is a critical time for CFHT. SAC reaffirms its support of an operations model in the coming years with MegaCam and VISION (plus an eventual IFU). Operating with fewer instruments will bring some efficiencies but also enable more ambitious LPs.

The future of CFHT relies on having a working telescope with interesting instrumentation, clear community support, and a development plan for the future. Executive Director Cuby presented a vision for the future of CFHT with MSE as a community astronomy project, fundamentally changing the model of how an observatory is designed and run.

VISION

SAC acknowledges the unique capability enabled by VISION, and is happy to see progress towards its realization. The timely arrival of VISION is vital to the near-term scientific future of CFHT.

RECOMMENDATION #1: SAC reaffirms its support for implementing VISION, the co-mount of ESPaDOns and SPIRou, as soon as possible, while making sure that future integration of an IFU remains possible.

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VISION + IFU

SAC supports the development of the IFU capability and believes it will likely prove most interesting when working in tandem with VISION as an enhanced spectroscopic capability for CFHT. To date, this project has been largely driven by technical considerations and it is now critical to have a well-developed science case for this capability. SAC sees the IFU as an important part of the CFHT development plan and recommends a reframing where the future of the observatory can be viewed as a continuum from the current CFHT to one with VISION and then an IFU, with the eventual total refurbishment to MSE.

The IFU project provides value in preparing for MSE, and it also provides CFHT with scientifically compelling new instrumentation opportunities in the short term. While both these elements are true, it is the latter that should be emphasized to scientifically engage the current partnership and to attract potential new partners. As described above, SAC feels that IFU working in tandem with VISION is a unique and compelling scientific opportunity. The science use of such an instrument suite is fundamentally different from that of a 4m-class MOS system or of MSE, and it is unrealistic to expect that users interested in IFU (+VISION) are the same users interested in MSE. It is therefore not helpful for the IFU to be presented to many communities in a way that explicitly ties it to MSE (on a vastly different timescale) and that does not explicitly present it as a component of the near-term future spectroscopic capabilities of CFHT i.e. alongside SPIROU, ESPaDOnS, and VISION, while also making use of the queue-scheduling advantages of CFHT and the Observatory’s proven ability for large programs. It is also likely that key scientists who can help develop the case and capabilities of IFU (+VISION) will be found outside of the MSE science team.

More broadly, the SAC is clear in its strong support of MSE for the long-term future of CFHT. Given the timeline involved, however, it is essential that CFHT proactively work to change the narrative surrounding the transition, from one where there is an abrupt change (where there is the current CFHT, and then there is MSE) to one in which CFHT scientifically evolves towards MSE, by making optimal use of its instrumentation, its capabilities, and near and mid-term instrumentation developments.

Small changes that demonstrate this change in narrative, and in mindset, which will likely have positive impacts, include dropping the term “Pathfinder” from describing the proposed new instrumentation. The pathfinder aspect is true, but it is likely not the aspect that will make this instrument compelling to the potential user community. In addition, CFHT may wish to consider changing the role “Director of MSE Programs’ to “Director of Development”, or equivalent. The latter suggestion is an explicit recognition that the development of CFHT towards MSE includes using the current and near-term instruments such as VISION to enhance the spectroscopic capabilities of CFHT. Finally, given the importance of the IFU in this context, SAC believes that all current efforts should be directed towards the IFU and not the associated MOS capabilities.

RECOMMENDATION #2:SAC recommends that a clear science case for the proposed IFU, likely working in tandem with VISION, needs to be developed as a top priority.

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RECOMMENDATION #3:SAC recommends that CFHT presents the current and future scientific capabilities under development as a single coherent narrative of the scientific evolution of CFHT, building on the current instrumentation suite and survey strengths of the facility, connecting to the enhanced near-term spectroscopic capabilities of VISION, the mid-term opportunities of IFU+VISION, to the long term capabilities of MSE.

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MSE Development

The MSE team has applied for several funding opportunities in the past year related to both MSE and the “Pathfinder” project. A $0.5M NSF ATI (Advanced Technology & Instrumentation) grant proposal led by Sam Barden was approved. The proposal will fund critical technology development for MSE spectrographs (wavelength splitting and pupil slicing). A $4M NSF MRI (Major Research Instrumentation) was revised and resubmitted in November. An NSF Mid-Scale Research Infrastructure-1 (MSRI1, $6M-$20M range) proposal to develop the 1000-fiber integral field unit will be submitted Jan 2024. A similar previous proposal was well received (recommended by a review panel to go forward to the next review phase, but then did not).

- Quad mirror telescope feasibility study

There is a natural bifurcation in the path forward towards MSE. One path is the original MSE design and the other is inspired by the recent concept developed at CFHT of a wide field quad-mirror anastigmat telescope design (Barden, Baril & Jones), which allows for a more compact telescope structure for a given primary mirror diameter. Note the weight (and cost) of a large (alt-az) telescope generally scales as the volume. This path allows for a CFHT replacement by a ~12-meter class telescope potentially supported by the existing pier and with a smaller volume dome. It is crucial to determine if this path is feasible or not. This requires two engineering efforts to be done as soon as possible: a) an engineering study to determine the load-bearing capability of the as-built existing pier and if there are non-invasive ways to re-enforce it, and b) what are the load-bearing requirements of such a telescope. Note that such a telescope design allows for much more multiplexing in the MOS mode and that allows for the possibility of a future second instrument at the other Nasmyth focus (e.g. a wide field imager). This design enables the multi-object spectroscopic capability of MSE, while also providing avenues for future developments. This is a scientifically compelling option that warrants exploration.

Decommissioning Plan

SAC heard from the observatory on a proposed decommissioning plan for WIRCam and SITELLE, that would see these instruments decommissioned at the end of 2026B. SAC thanks the Observatory for this plan. SAC agrees with the Observatory that it is important to keep these instruments available for the duration of the current associate partnerships given the demonstrated interest by the associate partners in the scientific usage of these instruments. SAC does not prioritize initiating new development activities for these instruments during this time and does not recommend effort be spent to integrate these instruments into Kealahou. SAC agrees that once these instruments are decommissioned, then, if feasible, they can be stored at CFHT.

RECOMMENDATION #4: SAC reaffirms its previous recommendation that WIRCam and SITELLE be decommissioned in the near future, and agrees with the Observatory that the natural timeframe for this is 2026B, once the current associate partnership agreements are complete.

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Future LPs

Due to the increasing budgetary pressure, the CFHT astronomy group will have to support observations with a reduced staff from 2024 onward. Given such constraints and the historically successful scientific impact of LPs, SAC agrees that a new round of LPs should be planned for the near future of CFHT. SAC noted the current LPs were expected to finish in 2024A; however, due to the significant weather losses in 2023A, the current LPs will require additional time (see recommendation below). SAC supports a call for new LPs starting in 2025A. SAC agreed that this call for LPs should contain the following aspects:

  • SAC proposes a call for 4-year LPs with ~80 nights per semester. The minimum number of nights for each LP is 50 nights (over 4 years).
  • The LP call should only consider programs using MegaCam, SPIRou, and/or ESPaDOnS. Given the current VISION schedule, it is unlikely to be ready before 2025A but should be available during this LP. The proposers for this LP call should be asked to discuss the potential of VISION to strengthen their science cases when it is online, if applicable.
  • Given the huge success of the CFHT Legacy Survey (CFHTLS) SAC advocates that more ambitious and larger programs be considered for this LP call, and foresees the best outcome would be 1 bright time program plus 1 dark time program. Programs with large RA coverage and a large number of nights requested will be considered with higher priority.
  • Furthermore, given the reduced number of staff, CFHT requested that LP proposers include a support plan for LP implementation, and explicitly provide resources to CFHT for their LP (e.g. data reduction, queue scheduling). SAC urges CFHT to provide a list of possible tasks for the LP team in the call and iterate with SAC before posting the call online. SAC notes that the queue merging should still be CFHT’s duty as individual teams could not merge the queue, but could provide refined targets.
  • SAC recommends keeping the usual proprietary time of one year after the end of the semester. The LP call should also allow for options with zero proprietary time which will be viewed favorably by the TAC.
  • The call should mention a possible model that the proposed LPs contain multiple medium-size work packages with different science goals to build larger programs and collaborations.
  • Providing publicly-available higher-level data products should be encouraged and will be viewed favorably by the TAC.

Finally, CFHT presented a tentative schedule for the 2025A LP call, and SAC recommended increasing the proposers’ preparation time and therefore extending the deadline of the proposal submission and suggested a reduction in the amount of external review time (from 6 weeks to 4 weeks).

RECOMMENDATION #5: SAC recommends a new LP call for programs to start in 2025A. We recommend the call be for 4-year LPs with ~80 nights per semester, using MegaCam, SPIRou, and/or ESPaDOnS with priority to proposed programs with a wide RA range and larger programs.

Statement from the CFHT Board of Directors:

Regarding recommendation #5: In consideration of both the current state of instrumentation and the interest in a future call for more ambitious Legacy Surveys, the Board asked the SAC to consider the merits of a shorter LP call this year. The SAC was requested to respond in early 2024 so a call for LPs could be released promptly. Those subsequent discussions led to the Call for LoI that was announced on Jan 31, 2024.

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User Survey Summary

SAC thanks the observatory for their efforts in surveying the user community regarding the near-term plans for CFHT. We were happy to see significant participation in the webinars and a strong response rate to the survey. The survey opened on September 19 and closed on October 19 with 158 responses recorded where 75% of the participants have used CFHT facilities during the last 5 years. Of ESPaDOnS or SPIRou users, ~50% expressed interest in using VISION. Survey respondents showed more interest in SITELLE compared to WIRCAM. A majority of users are interested in submitting a future Large Program while the general interest of using VISION is higher compared to “Pathfinder”. 60% of respondents indicated they are interested in using CFHT with MegaCam, VISION, and possibly “Pathfinder” for the next ten years.

RECOMMENDATION #6: SAC recommends that a summary of the main results of the User Survey be shared with the community.

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Development Activities

The Kealahou management system is complete and the Kealahou proposal review tool has been operational since the 2023 call. This system allows the NTACs to provide proposal feedback automatically to the PIs. Significant effort has been made in developing a self-hosted code repository allowing to bring the developed source codes back internally. The work on the User Management Tools has been completed and one key part is the construction of a link between the Kealahou User Management System and the Legacy Sybase user list. The first development of the K2 user interface for MegaCam has been started as well as the new Rapid Target of Opportunity mode. The VISION Instrument integration (Mode 1 & 2) will be started at the beginning of 2024. A safety system has been developed for VISION and the IFU with a possible design review in 2024. Some tests were performed to investigate if ESPaDOnS can be switched between different nodes without having additional calibration sets; the first results are not conclusive and need further testing. Tests on the Dichroic Beamsplitter from TBL show these optics should not degrade the performance of SPIRou with VISION.

Science Operations

  • MegaCam - Dry air system and improved aluminizing procedures seem to have slowed the usual degradation of the u-band photometric zero point following primary mirror re-aluminization. Filter exchanger jukebox mechanical failure caused the premature end of the July Megacam run. The coupler was rebuilt quickly, so the August run went as planned.
  • SPIRou- The temperature control system stopped working on three different occasions; installation of updated firmware has apparently prevented a recurrence of the issue during testing. Otherwise, the instrument has worked well with minimal loss of observing time.
  • GRACES - A break in both the star and sky fibers occurred sometime before the July run, which was intended to be the last. Camera inspection revealed no obvious damage, but the fibers will be removed to diagnose what happened. The July run will not be rescheduled, and decommissioning will proceed.
  • Cosine regulator - The new system was tuned to accurately reproduce the old system’s performance, though there is a slight difference at the zenith, which is not yet understood. The new system reduces the air compressor duty cycle from 82 to 31 percent, because there is no need for constant air bleed, resulting in an estimated $17,000 annual cost savings in electricity. SAC congratulates the team on this important work.
  • Cybersecurity - Increased emphasis on cybersecurity has taken place in response to the recent attacks on the Gemini and ALMA Observatories, including staff education, installation of malware detection software, implementation of stricter firewall rules, a more comprehensive backup strategy, improved network monitmonitoring, vulnerability scans, and observatory community engagement.
  • Bridge Crane - Failure of the crane prevented switching to the prime focus instruments MegaCam and WIRCam for their scheduled November (and now December) runs.
  • Compressed Dry Air System - Compressed air is being used in more systems with the M1 coating protection system and vortex coolers. The upcoming upgrade early in the new year is important.
  • Protection from Leaks - To mitigate against the possibility of an environmentally hazardous fluid leak migrating into the basement where it could get into exposed cinders, a sealant has been used to cover the cinders. CFHT may wish to shift to food-grade glycol to further mitigate the consequences of a leak. CFHT is switching to an above-ground 300-gallon fuel tank for the emergency generator to replace an underground 5000-gallon tank that is being decommissioned to eliminate any chance of leakage. This will enable 24-hour coverage. A reduced power expenditure hibernation mode might extend this for critical systems such as cooling and pump on IR detector dewar. A small standby generator could help save a thermal cycle on this valuable asset.
  • ASIVA - The camera’s infrared detector failed, and repair is not possible as the detector is beyond end-of-life support. An interim solution uses a camera with a significantly smaller field of view. A proposal to rebuild the camera with a new detector will be submitted to the MKSSOC for consideration at their December quarterly meeting.

RECOMMENDATION #7: Recommendation: SAC recommends including the current risk register as part of the document package for SAC meetings.

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Current LPs

LPs have suffered in 2023 due to poor weather as well as, for CLASSY and UNIONS, crane and jukebox issues preventing MegaCam observations. SAC proposes extending the LPs until the end of 2024B as a means to address several issues mentioned in the team reports. While UNIONS will have preference over CLASSY in priority, the requests by the two teams appear complementary in terms of RA distribution.

UNIONS

As UNIONS science goals are, in part, to gather complementary data to the Euclid mission, the successful launch and deployment of the space telescope in July 2023 is excellent news. Regarding observations, UNIONS has had a remarkably poor completion rate of 26% due to poor weather, technical issues (crane failure, Megacam filter jukebox), and non-validated data. The team reports ongoing discoveries, with the tentative identification of the faintest known Milky Way satellite and the shape of dark matter halos from weak lensing measurements. Regarding the timeline for completing observations, there is a sense of urgency expressed in the team’s report. Euclid will start its main mission in a few weeks and observe parts of the sky accessible from Maunakea in March 2024. This leaves only a few months to complete the Euclid northern ‘year1’ footprint before the nominal end of the current LP run (end of 2024A). An extension in 2024B, as proposed by SAC, would help with mid-to-late-2024B coverage of parts of the fields at dec=60-80. These observations would arrive ~6 months after Euclid coverage.

CLASSY

CLASSY has a 70% completion rate to date (201 validated hours vs 280 allocated) and will most likely surpass the 80% completion level before the nominal end of the current LPs. There is nonetheless a case for a further extension in 2024B; the science requirement of CLASSY can only be achieved with revisits of the same fields, which implies that not revisiting a field will lead to a loss of previously acquired data. The November crane failure leaves ‘orphaned’ fields observed in Nov. 2022, and without a revisit in 2024B, these observations will be lost. This strongly argues in favor of a 2024B extension, considering in particular that October/November is the period of year during which the UNIONS fields are inaccessible, limiting the conflict between the two LPs. The March-April and May-June fields have been completed in 2023A, which will alleviate the pressure on MegaCam time at the best time to access most UNION fields.

SPICE

SPICE observations are on track to reach full completion at the end of the current LP run with the number of validated nights matching the fraction of the elapsed LP run at the time of the report. The team reports on ongoing data analysis from all of the 3 work packages (blind search, transit follow-up, and PMS stars). Extension into 2024B may be beneficial to SPICE in allowing to finalize monitoring of targets

RECOMMENDATION #8: SAC recommends the observatory make best efforts to complete all current LPs by the end of 2024B. We note that when there is a conflict between UNIONS and CLASSY scheduling, UNIONS should take priority.

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LP and PI Publication Statistics

SAC thanks CFHT for collecting information on publications to compare the impact of PI and LP programs. CFHT-related papers include papers published by LP and PI teams, users of the CADC archives, and users of catalogs derived from CFHT data. SAC is pleased to see that with ~200 papers per year over the last 10 years, CFHT is the fourth most productive telescope in the world. Regarding the number of publications per night, CFHTLS has the largest number, followed by LPs, and then PI programs. Several approaches can be used to estimate the impact of a paper, but the general trend is that the highest impact results are from CFHTS followed by LP and then PI programs.

RECOMMENDATION #9: SAC recommends CFHT continue tracking publication impact statistics.

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Time Allocation Report

2023B represents a total of 183.15 nights (90.74 PIs + 77.41 LPs + 10D + 5E), with the most popular instruments being SPIRou, MegaCam and ESPaDOnS. 2024A is still in progress (ITAC on 11/28): but there were 79 proposals received for all agencies, with the usual trend of ESPaDOnS/MegaCam/SPIRou requesting far more than WIRCam and SITELLE. The pressure was the highest for CNRS (3.65), then OPTICON and NRC (2), NAOC (1.32), UH (0.8) then ASIAA (0.25). Note that snapshot proposals are not included in the pressure.

From 2000B-2024A, the pressure for NRC+CNRS+OPTICON is quite stable at above 2. A long-term study (2016A-2024A) shows that WIRCAM demand/allocation is smoothly decreasing, while SITELLE remains relatively stable, at a low level. From 2011B-2023B, for all instruments, the fraction of exoplanets/stellar physics is slightly growing while the high/low z-universe fraction is declining. Note also that since 2020A, ToO astronomy has been regularly asked and allocated, though poorly completed (often there are no alerts).

QSO

QSO continues to be an efficient mode of operation. In the 2023A, winter weather was unusually bad at the beginning of 2023 with 85% of the time lost. One full run of Spirou and ESPaDOnS was lost, in addition, the jukebox failure truncated a MegaCam run by 11 nights. Overall, the low completion rate for ESPaDOnS is due to bad weather. MegaCam and Spirou completion is only 65% due to bad weather and jukebox failure (for MegaCam). On the other hand, SITELLE had a high completion rate (84%). All Large Programs were impacted by bad weather. UNIONS is severely behind schedule while CLASSY and SPICE are largely on track. On the Agency side, Canada and Hawaii had ~40% completion, while France had ~85%. These differences between agencies were driven by particularly poor weather for ESPaDOnS (Canada) and WIRCam (UH) runs.

Seeing Report

SAC congratulates CFHT for the interesting analysis of the coeval monitoring of the seeing between CFHT and MKAM DIMM data. Overall the DIMM and CFHT seeing measurements are well correlated with some variations, possibly due to dome venting and airmass differences. The seeing trend over the last 13 years appears relatively flat. Comparisons can still be improved by taking into account the distance to the zenith of the CFHT observations. SAC encourages CFHT to keep monitoring the seeing evolution and if possible to compare the results to other observatories on Maunakea.

Operational and Development Priorities

  • Normal Operations
  • Kealahou - Megacam
  • VISION (including Kealahou mode 3)
  • IFU development (science case organization, technical development)
  • Quad mirror telescope feasibility

Next SAC Meeting

Three partial days, online in May (dates TBD).


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