101st Meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

11-13 May, 2022, Strasbourg, France

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

Recommendation 1 MSE Pathfinder Science Case Development
Recommendation 2 MSE Pathfinder Development
Recommendation 3 Implementaton of VISION mode 1 and 2
Recommendation 4 Readiness of Implementaton of VISION mode 3
Recommendation 5 Primary Mirror Pneumatic Support Repair
Recommendation 6 Analysis and monitoring of Image Quality Degradation
Recommendation 7 LP Science Goal Progress

Report of the 101st meeting of the CFHT Scientific Advisory Council,
May, 2022

The 101st Science Advisory Council meeting was held in a hybrid format (Strasbourg and online) from May 11-13 2022. SAC members St├ęphane Arnouts (vice-chair), Étienne Artigau, Anthony Boccaletti, Sylvie Cabrit, Eugene Magnier, Alan McConnachie, Laura Parker (chair), Mathias Schultheis, David Tholen and Tracy Webb attended the meeting. The CFHT interim Executive Director Andy Sheinis, interim Director of Engineering Kevin Ho and Director of Operations Daniel Devost gave presentations and participated in discussions together with several CFHT staff members. Jennifer Marshall gave a presentation about the status of MSE. SAC notes that this was our last meeting with Andy Sheinis in the role of interim Executive Director. We would like to thank Andy for his service and for always engaging with SAC in a productive and positive way. SAC also looks forward to working with the incoming Executive Director Jean-Gabriel Cuby.

This meeting immediately followed the 2022 Users' Meeting. Given that the transition from CFHT to MSE is not imminent it is critical that CFHT remain a scientifically competitive facility with exciting instrumentation in the coming years. At the same time, we know that there is no capacity to design and build new facility instruments while also supporting MSE development. SAC was excited to hear more about the VISION proposal and the MSE pathfinder project at both the Users' Meeting and at the SAC meeting. These developments would keep CFHT at the forefront of astronomy in the coming years.

At this and previous SAC meetings we have had extensive discussions concerning how to make sure the LPs and PI programs can be scheduled so that programs can efficiently reach completion. At the next SAC meeting we would like to devote more time to this topic, which is particularly timely because of: 1) lessons learned from scheduling challenges with the most recent round of LPs, 2) more timing constraints on the horizon with programs requiring monitoring and an expected upcoming increase in targets of opportunity, and 3) valuable feedback received at Users' Meeting.The observatory staff does an incredible job with scheduling in a very constrained environment, but with 5 instruments and complex observational requirements SAC feels this is a topic worth exploring further, including a discussion around not scheduling all instruments in every semester,


SAC heard from the MSE Project Office on recent developments in the project, including the consideration of a new design that could significantly increase the multiplexing and versatility of MSE. SAC was also interested to hear of upcoming staffing changes and looks forward to the successful completion of the Transition Review planned for later this year. In addition, SAC thanks Jennifer Marshall for her excellent work as the MSE Project Scientist and looks forward to working with her replacement.

SAC was excited to learn about the concept for an MSE pathfinder instrument on CFHT. SAC agrees with the Project Office that such an instrument could present an exciting scientific opportunity for the CFHT and MSE partnerships, while also providing new strategic opportunities to advance MSE development activities and retire key risks, especially given the longer-term uncertainties that remain surrounding development on Maunakea. The development of the pathfinder will require close collaboration between the CFHT and MSE communities and the CFHT observatory and will require near-term funding sources to be identified. SAC encourages the Project Office to explore multiple funding avenues to ensure timely funding for the pathfinder. SAC looks forward to being kept abreast of relevant developments as they occur.

The development of a specific survey for the MSE pathfinder - even one that may be subject to change as new partners join - is viewed by SAC as an essential element of the proposal that needs to be developed. The completed scientific and technical proposal is a critical tool for advancing this instrument concept within the CFHT partnership as well as for attracting new partners and soliciting funding.

RECOMMENDATION #1: SAC recommends that a community science team for the MSE pathfinder be formed and that a science case is developed alongside the technical concept as a matter of high priority.

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RECOMMENDATION #2: SAC recommends developing the MSE pathfinder instrument concept as an excellent platform both for future CFHT science and for the development of the MSE Observatory.

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SAC was pleased to see the technical report for the conceptual design of the VISION project prepared by the IRAP team, inspired from a similar project at the TBL in France. VISION allows CFHT to co-mount SPIRou and ESPaDOnS on the same mechanical frame while offering three observing modes owing to a sliding mechanism: SPIRou alone (mode 1), ESPaDOns alone (mode 2), and both instruments simultaneously (mode 3). Mode 1 has no optical parts with the beam going straight to SPIRou, mode 2 implements a pair of mirrors to direct the full beam to ESPaDOns, and mode 3 requires dichroics to split the IR and the visible with a transition in the range 900-950nm. The design is optimized in both spectral regimes to maximize the throughput and to minimize the cross-talk between Stokes parameters in order to preserve the polarimetric efficiency. The team managed to reduce the incidence angle on the mirrors/dichroics to 12° to accommodate the F/8 beam from the telescope. The analysis of the Mueller matrices for mode 3, taking into account the F/# and alignment precision of 5 arcmin, shows satisfactory results with respect to the throughput and cross-talk requirements, except for the visible channel (400-900nm), although localized in 4 narrow spectral bands, thus not affecting the science too much.

VISION can simplify operations at CFHT by reducing the number of instrument exchanges. In addition, if mode 3 reaches nominal performance it can presumably become the default mode, hence effectively reducing the number of instruments operating at the telescope. While mode 1 and 2 are straightforward to implement and offer operational savings for CFHT, mode 3 requires further development and dedicated resources. A management plan is proposed with distribution of the work in packages with a timeline, together with cost (152k euros) and FTE (3.6) estimates, to which CFHT can contribute at a level of 50k euros and 1.5 FTE, for the machining of the mechanics internally, and for the software development. The next step in the project is for IRAP to assess the feasibility of the dichroics by iterating with CILAS and to provide further information about the development at TBL.

SAC recognizes the potential of VISION in terms of science and operational gain, at a relatively low level of investment. SAC would like to see a consolidated conceptual design and management plan for mode 3 by fall 2022 to discuss at our next meeting.

RECOMMENDATION #3: SAC recommends pursuing and eventually implementing VISION mode 1 and 2.

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RECOMMENDATION #4: SAC recommends that CFHT should report on the readiness of implementation of mode 3 at the next SAC meeting.

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SPIRou Upgrade

The SPIRou upgrade is planned to take place in July. The instrument will be warmed up at the beginning of June and back to operations by mid-August. IRAP and Winlight worked on a holder for the octagonal fibers in the slicer, with the aim of improving the scrambling and reducing the RV noise level. A test bench is being set up at IRAP to demonstrate the scrambling gain and to avoid removing the SPIRou slicer from the spectrograph. If no gain is observed, the slicer will remain in place. The spectrograph cold heads will be replaced or repaired. A thermally isolated fiber will be installed to help reduce the thermal background. To reduce persistence, an LED will be mounted on the spectrograph to flash the detector after bright sources and calibrations. The Cassegrain unit is being modified to save time in alignment of the fibers and improve thermal background. In addition, several attempts to reduce the thermal background were not entirely conclusive so CFHT will be using both glycol-chilled cold plates and a vortex cooler.


SAC heard about the ongoing development efforts for K1 and K2 and the near completion of the former package. The proposal submission component of K1 will be done by the end of May while the review component will be ready by the end of September, with K1 being released for the 2023A Call. The operational K2 package has been expanded to ESPaDOnS and will soon include, in order, SITELLE, MegaCam and WIRcam, with the order set by instrument need. SAC thanks the Kealahou team for their continued efforts in this area.

Primary mirror pneumatic support

SAC learned about the failure of the primary mirror pneumatic support coincident with an earthquake at the summit. The resulting leak causes the primary mirror figure to be poorly controlled with concomitant image quality degradation. The PSFs were shown to have high ellipticity over much of the field, including double-lobed images. SAC notes that the PSF in the images are clearly unacceptable for most science programs and compromises CFHT's historic strength of excellent image quality.

The cause of the problem is believed to be the failure of the seal for one of the supporting pucks in the inner ring of the primary mirror support. In order to repair the damaged puck or associated components, the staff will need to remove the primary mirror. This operation cannot be performed until additional parts are delivered (expected end of May). The planned repair work will be performed in parallel with an early mirror recoating to avoid a second primary mirror removal operation planned for the next year (2023). The anticipated down time is 7 - 10 days. The repair work will be performed as soon as possible, and losing some nights is preferable to continuing operations with low image quality. The observatory may choose to adjust the timing of the upcoming Megacam and SPIRou runs in consultation with the PIs to make best use of the telescope before the repair is performed.

RECOMMENDATION #5: SAC recommends that CFHT pursue the primary mirror pneumatic support repair as soon as possible.

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Dome Vents

All dome vents are operational again, opening to two-thirds of the total open position. CFHT identified issues with ice and have a new procedure in place to reduce accumulation.

It has been noted that the image quality has degraded in recent years. This trend has apparently been observed at other observatories as well so it is therefore unlikely to be solely due to the dome vents, which have previously been found to improve seeing by ~0.1".

RECOMMENDATION #6: SAC recommends that CFHT analyze the historical data and monitor the ongoing IQ situation with currently available tools and provide updates at future SAC meetings.

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Astrometric Camera

SAC congratulates CFHT staff on successful deployment of the Astrometric camera in January 2022. The low astrometric residuals after a pointing model correction appear well within the tolerance to enable efficient acquisition of targets by SPIRou and ESPaDOnS. The reduced acquisition time will improve the overall observing efficiency.

Operations Updates

SAC heard about a number of important updates at the observatory, including improved stability in zero points, cold head replacement and maintenance on WIRCAM, upgrade to the primary mirror cosine regulator, and the new hydraulic power unit. SAC would also like to note that a new dome bridge crane access platform is now in place and appears much safer than the previous system.

Large Programs


The completion rate of CFIS of 78% lags behind the required 80% of the original allocation. SAC decided not to trigger a completion review at this time, given the remaining fields are Spring targets and uncertainty around the timing of the mirror support repairs. SAC will continue to monitor CFIS completion and may trigger a completion review before the end of 22A if required.

Despite this completion rate, SAC was pleased to see the scientific output of CFIS ramping up and congratulates the team on the wide variety of science topics explored with the data that are in-hand. An ongoing issue remains the value of the hours-to-nights conversion factor: CFIS validation data clearly indicates a lower rate of 3.7 hrs/n, well below the originally documented 5.5 hrs/n, and still below the newly recommended 5 hrs/n. SAC appreciates that this is a consequence of the strict IQ limit required by the team and that this is largely responsible for the lower completion rate. SAC was also alarmed to hear of the possible degradation of the IQ at the MK site, seen in the CFIS data and encourages CFHT to monitor this situation with currently available tools (see related recommendation).


The SIGNALS large program has had very successful recent semesters and has now obtained more than 80% of the original allocation. SAC was impressed with the science and methods presented at the Users' Meeting and looks forward to the teams sharing their advanced data products in the near future to be used by the community.


The progress on this program has ramped up over recent semesters and has reached a global validation rate of about 87% (based on SNR only). The monitoring rate of priority sources, i.e. the ratio of validated to planned visits, was low in the first 2.5 semesters (20%-30%) due to both technical and operational issues. This rate was much improved (60%-80%) in the last 4.5 semesters, following SAC's recommendation of avoiding transits at similar RA on consecutive nights, and of having SPIRou runs of at least 10 nights. SAC commends the QSO team for their efforts in implementing these scheduling constraints. Due to the low initial monitoring rate, the final useful sample size is reduced (62%-74%) from the original request. Nevertheless, impressive results were obtained, and presented at the Users' Meeting, such as RV detections of TESS planet candidates, the first density measurement of a young planet, and the first magnetic map of an outbursting young star. SAC congratulates the team for the growing science output, which includes 17 papers published or submitted and 25 in preparation and is looking forward to the longer term analysis of the full dataset.

Future Large Programs

The 2022 call for LP proposals resulted in 9 letters of intent and 7 submitted proposals. The proposals addressed a wide range of science questions and requested 4 of the 5 current instruments (all but WIRCAM). The oversubscription for LPs was ~2, typical for previous LP calls. The LPTAC meets in late May and SAC will convene in June to make its recommendations.

The LP completion policy can trigger a completion review if a given LP has not reached 80% completeness and/or the proposed science goals cannot be reached. In order to monitor science goal progress SAC would benefit from additional information from the PIs, which could include suggested metrics for monitoring LP science progress when validation rates do not capture all relevant information.

RECOMMENDATION #7: SAC recommends that LP PIs be asked to provide information in their reports that quantifies progress in achieving science goals.

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Time Allocation Report

SAC heard details of the time allocation statistics for 21B and 22A semesters as well as the proposals for 22B. SAC remains impressed by the low time losses caused by technical failures and congratulates the CFHT staff on their proactive approach that prevents unnecessary losses in observing time. The continued interest in all of the instruments across the entire partnership is encouraging, as is the healthy pressures on the instruments. SAC continues to encourage CFHT to promote SITELLE outside of the dominant user community in Canada.


The five CFHT instruments are operated in Queue Service Observing mode. At the end of the 21B semester, the group of Remote Observers was down from 4 to 3 and the process of hiring a new RO is ongoing. SAC is pleased to see that the first test of the new Kealahou QSO interface in November 2021 with ESPaDOnS was successful. For 21B, MegaCam had 41 nights allocated, WIRCam 8 nights, ESPaDOnS 20 nights, SITELLE 17 nights and SPIRou 84 nights. The time lost due to technical issues continues to be at a very low level (<2%).

For SPIRou the completion of A and B programs was very high with 111% and 80% respectively, due to a small amount of time lost with bad weather, and a generous number of nights scheduled. SITELLE and ESPaDOnS also had a good completion rate of A+B programs with 89% and 72% respectively. On the other hand MegaCam and WIRCam have a low completion rate with 57% and 58% respectively. MegaCam was the most affected by bad weather (39% of time). For WIRCam the reason for the low completion rate is essentially due to two A programs that could not be observed during the scheduled runs. All the PI agencies fared about the same overall during semester 2021B. The SIGNALS and SLS programs are now reaching 80% completeness while CFIS, hit by bad weather, is a bit behind.


The banked CFHT allocation for GRACES continues to grow but is still below the threshold of 14 nights overall deemed necessary to make a useful call for proposals for France. SAC anticipates another CNRS CFHT-Gemini call for proposals next semester.

2022 CFHT Users' Meeting

SAC congratulates the LOC for organizing a successful CFHT Users' Meeting in hybrid format with some participants at the Observatory in Strasbourg and others joining remotely. SAC was impressed by the excellent science talks highlighting the productivity of CFHT and noted the many talks using data from the current generation of large programs. As lessons learned for the future, SAC recommends surveying the user communities before Users' Meetings to help prepare for discussions during the meeting. The hybrid format allows for participation of users who could not attend or prefer not to travel but is a more challenging format for discussions.

Operational and Development Priorities:

  1. Primary mirror support repair
  2. Normal operations
  3. K1
  4. MSE, including pathfinder
  5. SPIRou upgrade and DRS support
  6. VISION modes 1 and 2

Next SAC Meeting

The next SAC meeting is targeted for the week of November 14-18 2022, with the exact dates to be determined later. We hope that the meeting will be in-person (allowing for remote participation as needed) in Hawaii.