94th Meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

20 - 21 November, 2018, Waimea, Hawaii

After deliberation during its December 2018 meeting, the CFHT Board of Directors, in consultation with the Executive Director, endorse the following SAC recommendations:

Recommendation 1 Endorsement of MSE as CFHT Scientific Future
Recommendation 2 Continued Work with SPIRou Team
Recommendation 3 Replacement of SITELLE Camera Dewar Window
Recommendation 4 Solution to Dome Vent Issue

Report of the 94th meeting of the CFHT Scientific Advisory Council,
November 2018

The 94th Science Advisory Council meeting was held at CFHT Headquarters on November 20-21 2018. SAC members Anthony Boccaletti, Stéphane Courteau, Emanuele Daddi, Tristan Guillot (vice-chair), David Lafrenière, Eugene Magnier, Nicolas Martin, Roberto Mendez, Kim Venn and Chris Willott (chair) attended the meeting. Sophia Dai from NAOC also attended. The CFHT Executive Director Doug Simons, and many other CFHT staff, gave presentations and participated in discussions. SAC appreciated the opportunity to interact with so many staff members. SAC thanked Mercedes Stevens for her support to this and all previous meetings of the CFHT SAC.

Director Simons reported on the extensive community outreach activities undertaken by CFHT. SAC views this engagement as very important for both the short-term and long-term success of CFHT. The Director also reported on the Environmental Impact Statement process underway as the first step in renewing the master lease for the Mauna Kea Science Reserve.

Maunakea Spectroscopic Explorer (MSE)

SAC heard about the latest MSE developments from Kei Szeto, the Project Manager, and Alan McConnachie, the Project Scientist. SAC was impressed by the maturity of the project, reflected by the heroic effort invested in the Conceptual Design Phase by the Project Office, summarized into a very thorough "MSE book" that is now public. MSE is the most advanced facility of its kind and a recognized need for the astronomy community. The recent expansion of the MSE Science Team, now representing more than 330 scientists in 31 countries, is also very encouraging given the need for an extended partnership. At this stage, public support from the science community is essential for the future of the project.

RECOMMENDATION #1: SAC endorses MSE as the scientific future of CFHT. SAC supports proceeding to the Preliminary Design Phase.

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SAC congratulates the SPIRou instrument team and CFHT staff for excellent progress in commissioning this complex instrument since the last SAC meeting. Although there is still work to do in both hardware and software improvements, the current performance is very encouraging. SAC notes that replacing one rhomb led to some improvement in the blue throughput and is optimistic that replacing the second will provide a further gain. Although the Y and J band throughput are still below technical specifications, the instrument meets the top-level signal-to-noise requirement and the impact on most science goals appears modest.

The thermal background in the K band (above 2.1 microns) is higher than expected. CFHT and the SPIRou team are investigating improvements to reduce the background, which will increase the S/N in this wavelength range for faint targets. SPIRou is obtaining relative radial velocity (RV) rms of 2 m/s in sequences lasting on timescales from hours to nights, although there are still some RV jumps that need to be understood and corrected. There is still room for RV improvement through development of the data reduction system (DRS) and improved telluric subtraction using a larger library of telluric standards.

The instrument Acceptance Review is tentatively scheduled for January 2019. As part of this review, SAC will consider whether the scientific performance of the instrument and the DRS is adequate to begin the SPIRou Legacy Survey. To enable this decision, SAC will request an updated SLS proposal/observing plan based on the current and expected instrument performance.

RECOMMENDATION #2: CFHT should continue to work with the SPIRou team to improve the instrument performance and enable the cutting-edge science that SPIRou promises.

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As part of the investigation for the source of the image quality degradation at the edge of the field of view (FOV), the SITELLE cameras were sent to Laval for characterization and testing; however, the results of the activities conducted in Laval were mostly inconclusive and an accurate model of the as-built optics, to integrate into the Zemax model, could not be developed. Meanwhile, the CFHT team found that a tilt of the whole camera mount could explain some of the features seen in the out-of-focus images obtained on sky. After confirming that such a tilt was present, they proceeded to correct it, as well as a tilt of the CCDs, resulting in a significant improvement in image quality in the corners of the FOV. In addition, there is, by the design of SITELLE, a field curvature preventing best focus to be achieved simultaneously across the field. The CFHT staff determined that replacing the dewar window by a field lens would significantly improve the uniformity of the image quality across the field. While some level of unknown wave front error would remain in the SITELLE optics, these two corrections would bring the image quality to an acceptable level for long-term operations, with no need for a more in-depth investigation or other modifications. SAC congratulates the CFHT staff for their effort in resolving this issue. SAC encourages CFHT to proactively contact all SITELLE users to inform them of improvements as they occur.

RECOMMENDATION #3: CFHT should proceed with the replacement of the SITELLE camera dewar window by a field lens to mitigate the field curvature inherent in the design and provide high image quality across the full field.

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ESPaDOnS was affected by a failure of the camera focus stage in mid-June, which was quickly fixed, and then a lightning strike in mid-August which affected all the stages in the ESPaDOnS enclosure, including those on the GRACES bench. SAC is impressed by the quick repairs and adjustments made by the ESPaDOnS team to get the single mode working manually, and complete the daytime Venus observations. One hypothesis is that the lightning entered the ESPaDOnS enclosure through the steel strain relief cable inside the GRACES fiber jacket: discussions are needed to see if it would be worthwhile trying to better ground the jacket. Full repairs and realignment to ESPaDOnS were completed by mid-September; work is still required on the GRACES bench (CFHT staff have plans to work with Gemini staff over the coming month to be prepared for the January 2019 GRACES run).

Apart from this issue, GRACES appears to be working well, and is a capability in high demand from the Gemini community. The inclusion of the French exchange time from GRACES into the Gemini queue has been satisfactorily resolved as of 2018A.


MegaCam suffered data corruption in 2017 which was traced to problems with the SLINK communications board. This hardware is obsolete and spares cannot be found anywhere. CFHT staff heroically replaced individual components on 5 boards, enabling MegaCam to have two operational boards plus three spares. However, this solution is considered by the staff to be temporary; they have begun design work on a replacement solution using Ethernet gigE technology. The hardware cost of this effort is modest (~$3k), but will require a total of ~0.6 FTE to implement. SAC considered this effort to be important in light of the uncertain longevity of the refurbished SLINK board.

In July, one of the MegaCam filters got stuck when returning to the jukebox because of a screw which had backed out about 1 mm. Fixing this issue required disassembling the instrument but neither the filter nor the slide rail were damaged. A threadlocker was applied to the screws to avoid this issue happening again.

Operations status

The dome vent L2 has been inoperable since August 2018 after becoming stuck. As a safety precaution all dome vents are remaining closed, until the vents can be repaired/upgraded to prevent this problem. This likely has consequences on the delivered image quality with a knock-on effect of a drop in efficiency for programs using the QSO-SNR observing mode. The issue is compounded by the lack of lift equipment to access the vents. In the near term, it is possible that some vents will be opened before the observing night begins to flush the dome air, however a long-term solution to provide full venting throughout the night is extremely important.

RECOMMENDATION #4: CFHT should find a solution to the stuck dome vents issue as soon as possible in order to recover CFHT’s world-renowned image quality.

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Evaluation of refurbishing the coating chamber was previously identified as a priority by the SAC given that re-coating every 2 years instead of 3 can save 4+ nights of time due to higher blue throughput. The analysis showed that the tips of the electrodes have deteriorated. A new design to replace in situ the bottom part of the 244 electrodes holding the wires is proposed. Schedule, cost and manpower were evaluated so the modification can proceed.

The DEC cable wrap is getting stiffer at low temperatures as the plastic of the bundle is aging. To get around this problem, the cables will be compartmentalized in smaller bundles to provide more slack. This should be effective before the end of the year.

The new building fluid cooling system has been in operation since February 2018 at 65% capacity so there is still room for heat load, and its operation is significantly cheaper than the previous system.

Large Programs


SAC appreciates that the weather in semester 18A had a devastating impact on most CFHT programs, including CFIS. SAC is also grateful for the team's detailed summary, including realized validations and expected projections. CFHT is working towards an LP completion policy to be announced in the coming months. Only then will SAC be able to inform the CFIS team about the expected completion timeline. The team’s next report to SAC should include a detailed review of scientific accomplishments and publications as well as an additional figure reporting the combined u+r QSO validation and projections. The latter will enable SAC to track expectations for the full survey.


The program is progressing well with 133.8 hr validated out of 150 hr allocated so far at the midway point. One significant result was the discovery of a “spectral clone" to Beta Pic b — a result that should improve our understanding of these young, massive planets/brown dwarfs (Dupuy, Liu et al. ApJ 2018). By combining the obtained astrometric data with Keck AO imaging, the survey is also beginning to yield dynamical masses for the components of brown dwarf binaries. This should eventually allow to better constrain evolution models of these objects. SAC is looking forward to the successful completion of this program.


SAC appreciates that the weather in semester 18A had a devastating impact on most CFHT programs, including VESTIGE. SAC is pleased to see the team's progress, with a healthy publication stream and contributions to scientific symposia, despite a delayed acquisition rate. CFHT is working towards an LP completion policy to be announced in the coming months. Only then will SAC be able to inform the VESTIGE team about the expected completion timeline. The team’s next report to the SAC should include a detailed review of scientific accomplishments.


SAC discussed the target duplication protection policy applied to the SPIRou Legacy Survey. The current policy is too restrictive in preventing all observations of SLS targets. For example, an atmosphere characterization transit observation has a very different science goal and time-sampling compared to a radial velocity determination of planet mass. SAC will recommend a revised version of the duplication policy.

Large Program Completion Policy

SAC was pleased to see progress towards the adoption of an LP completion policy to ensure that Large Programs accomplish their original science goals. After several iterations on the draft policy, it is hoped that a final version will be adopted at the next Board meeting.

Commissioning and Science Verification Data Policy

SAC has been working with CFHT on a policy to cover data rights for data obtained during the technical commissioning and science verification phases of new instruments and major instrument upgrades. The draft policy will be sent to the Board for review.

Telescope Use and Scheduling

SAC was presented with a detailed report on telescope usage in 2018A (complete) and 2018B (ongoing), as well as statistics on telescope pressure and instrument demand for 2019A.

Technical losses in 2018A were low, but weather losses were abnormally high in the first part of that semester. Semester 2018B appears to be more typical so far.

Telescope pressure in 2019A from the different agencies has remained at healthy levels. Instrument demand in 2019A shows that SPIRou, MegaCam and ESPaDOnS are the most requested. The comparatively low demand for SITELLE is alarming, considering its unique capabilities, although this may be partly because the science is being done within the SIGNALS LP.

QSO Report

A report on Queue operations was presented. SAC concurs that the queue chain of operation is efficient and robust. The low completion of several 18A programs is attributed to bad weather during much of the semester, and for MegaCam compounded by a failure of the filter jukebox in July, which eliminated 11 nights from the original schedule. CFHT staff have done an excellent job of switching instruments when problems arise in order to minimize loss of observing time.

The CFIS team report noted that the median historical MegaCam validation rate since 2003 has been 5.0 hrs/night rather than the 5.5 hrs/night used by QSO and by the original CFIS proposal assumptions. The recent bad weather may be a contributing factor; SAC will continue to monitor the validation rate but does not recommend any change at this time.

2019 CFHT Users' Meeting

The next CFHT Users’ Meeting will be held in Montréal from 19th to 22nd May 2019. Nadine Manset (LOC chair) reported on agreements with the hotel venue. A hotel registration link will be made available after people register for the meeting. It was noted that May is a busy time in Montréal so hotel bookings should be made early.

The scientific focus of the meeting will be CFHT’s present and future. The SOC will work in the coming months to invite speakers covering all aspects of CFHT. Contributed abstracts will be accepted until 11th March 2019.

Operational and Development Priorities

  1. Normal operations
  2. SPIRou
  3. MSE
  4. SITELLE image quality
  5. Dome vent repair/upgrade
  6. MegaCam SLINK replacement

Next SAC Meeting

The next SAC meeting will take place in Montréal, Canada, on Thursday 23rd and Friday 24th May 2019, immediately following the CFHT Users’ Meeting. The expected location is the Université de Montréal, with local host David Lafrenière.