95th Meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

23-24 May, 2019, Montréal, Canada

After deliberation during its Quarterly Report-II 2019 teleconference, the CFHT Board of Directors, in consultation with the Executive Director, endorse the following SAC recommendations:

Recommendation 1 Monitoring and Reporting of On-Sky Data Collection
Recommendation 2 Evaluation of SPIRou Rhomb Throughput
Recommendation 3 Sale of Spare SPIRou H4RG
Recommendation 4 Studies of Co-mounting of ESPaDOnS and SPIRou
Recommendation 5 Solutions to Functionality of Dome Vents

Report of the 95th meeting of the CFHT Scientific Advisory Council,
May, 2019

The 95th Science Advisory Council meeting was held at the Université de Montréal on May 23–24 2019. SAC members Anthony Boccaletti, Stéphane Courteau, Emanuele Daddi (vice-chair), David Lafrenière, Eugene Magnier, Nicolas Martin, Roberto Mendez, Tracy Webb and Chris Willott (chair) attended the meeting. The CFHT Executive Director Doug Simons, Director of Engineering Andy Sheinis and Director of Operations Daniel Devost gave presentations and participated in discussions at the SAC Meeting and at the preceding Users’ Meeting.

Maunakea Spectroscopic Explorer (MSE)

SAC heard the latest developments regarding the MSE project from the CFHT Executive Director and the MSE Spokesperson during the Users’ Meeting. SAC appreciated that efforts are being invested into expanding the partnership and ensuring visibility and support from the CFHT communities. The revised and expanded science case, published during the first half of 2019, shows the breadth of science that MSE enables. It involved a significantly enlarged science team of almost 400 members, which SAC takes as a very positive sign.


SPIRou passed its acceptance review in January and started science operation in semester 19A. SAC congratulates the CFHT team and the SPIRou team for this significant achievement.

The delivered radial velocity (RV) precision is currently at the level of ~2 m/s, being limited mainly by shortcomings in the data processing and not by the instrument. It is expected that the RV precision will improve with updates to the processing software and collection of a larger library of telluric standard observations. All of the data, raw and processed, are available to authorized users at the CADC. Science Verification and some Technical Commissioning data are public. As the data processing software is updated, all data at the CADC will be reprocessed and users will be informed of the details of the update through email communication and a web-based log.

Overall instrument throughput has been a known issue with SPIRou, particularly in the blue part of the spectral range where transmission is significantly lower than anticipated. Most of the problem was traced to the rhomboid prisms in the Cassegrain unit. A further sudden drop of ~40% in transmission occurred during the February run, traced to a likely separation of the two optical pieces making up one of the rhombs. The faulty rhomb was replaced and transmission went back up to its previous level. As it stands, one of the two rhombs has significantly lower throughput than the other. The second rhomb is needed only to acquire linear polarization and removing it from the instrument could have a low impact on science as it appears that a majority of the programs doing polarimetry need only circular polarization. From data presented to SAC, it seems that operating SPIRou with a single rhomb in place would recover a factor of 2 in transmission. However, SAC notes the available instrument transmission measurements, based on an artificial star flux relative to the background, are imprecise and inadequate to monitor the issue with confidence. Looking forward, new rhombs with higher transmission and improved durability could be procured. A design for rhombs with air-spaced pieces with proper coatings seems possible, which would prevent the separation problem described above from recurring.

The current readout overhead of the SPIRou detector is unreasonably large at 20-30 s. The reason for this is unknown and hard to diagnose without access to the source of the manufacturer-supplied detector control software. An in-house C-based software solution was designed and preliminary tests indicate an excess overhead time of only 3 s on average; full testing still has to be completed. If this is confirmed, the time saved would amount to 30-60 minutes per night. SAC commends the CFHT staff, in particular Sidik Isani, for their excellent and proactive work in developing this effective solution.

The thermal background is currently a factor of ~2 above specifications in the K band. CFHT is working to resolve that issue and has already implemented cooling of the fiber coupling interface and will next proceed to cool the entire coudé room. It is expected that this will lower the thermal background, although reaching the specification may require further work.

From the detector procurement process CFHT is in possession of a high-quality H4RG detector that currently serves as a spare for SPIRou. Given the low probability of detector failure, this device could be sold to generate revenue.

RECOMMENDATION #1: Implement regular and precise monitoring and reporting of the overall instrument transmission using on-sky data collected as part of normal operations.

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RECOMMENDATION #2: Evaluate whether default SPIRou operations with only one rhomb to achieve higher system throughput is beneficial to the overall science output. CFHT should consult with PIs to understand which programs may be affected. Additionally, study whether procurement of rhombs from a new vendor would be likely to improve the long-term performance of SPIRou.

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RECOMMENDATION #3: Pursue the option of selling CFHT’s spare SPIRou H4RG.

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The problem of field curvature is being addressed. Two field flattening lenses were ordered by Université Laval and delivered to Waimea. Image quality is expected to be up to specifications with those lenses. Mounts have been fabricated and blackened. This solution will be implemented prior to, and tested during, the upcoming engineering nights and expected to be completed prior to the first science run of 19B.

A second problem, modulation efficiency (ME) as determined by laser calibration images, shows variations from the start to the end of the exposure. The cross-polarizer was examined but showed no effect. The current level of ME variation is a lesser concern regarding the maintenance of good instrument efficiency. It is deemed a low priority.

The problem with dust particles falling off the integration sphere has been fixed. The pointing offsets were due to installation of the new Cassegrain guide camera; these have also been fixed and will no longer affect SITELLE’s pointings.


Both ESPaDOnS and GRACES were successfully repaired after the damage of the lightning strike that occurred in August 2018 and are now working optimally.

GRACES-enabled Gemini programs have started to be executed for France in band A queue. In 2018B, 3 projects were allocated and fully completed, for the planned 18.5h of observations. In 2019A, 2 projects were allocated with one finished and one still ongoing. No Gemini time was offered through CFHT for 2019B. The exploitation of Gemini time through GRACES for the French community is now working successfully. GRACES/ESPaDOnS demand by Gemini observers is still strong at 170h in 2019B.

SAC discussed two options for co-mounting ESPaDOnS and SPIRou, which would reduce the number of instrument exchanges and thus the load on the CFHT staff. It would also come with desirable science benefits, particularly for the option where both instruments can be fed simultaneously, although possible drawbacks should be investigated (loss of throughput, astigmatism introduced by extra dichroics and mirrors, impact on polarization cross-talk).

SAC supports the development of the required internal studies to investigate this option technically. Developing a proper science case for the co-mount is also important.

RECOMMENDATION #4: Carry out detailed studies of co-mounting ESPaDOnS and SPIRou, considering options for simultaneous observations or simple instrument exchange. These should focus on the engineering effort to do this work, time saved by fewer exchanges, technical feasibility/risk, cost, along with science cases for each option.

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The MegaCam SLINK replacement project initiated in 2018 has been proceeding well. The replacement ethernet components have been acquired and the necessary supporting boards have been designed and implemented. Since the ethernet card chosen for the project replicates the 32-bit transmission mode of the SLINK, the supporting board design was relatively simple. A challenge to the team came from the need to re-program the CPLDs on the SHARC uP board as the software needed is no longer supported. A work-around with virtual Windows installations was needed to allow the older software to be run. This project is expected to be completed in June 2019.


WIRCam has continued to work without problems since the repairs after damage due to the August 2018 lightning strike.

SAC discussed the possibility of future decommissioning of WIRCam in light of the low demand in recent semesters and given the high pressure that supporting 5 instruments and many instrument exchanges puts on CFHT's staff. SAC also discussed the importance of WIRCam for UH and associate partners. SAC recognizes that despite limited use, WIRCam is delivering good science and requires minimal engineering effort when not in use. SAC will continue to monitor the demand of WIRCam in the coming years, but does not consider the need to take any action.

Operations status

The dome vent issue has been identified as being related to the accumulation of water in the door assembly, which turns to ice when the outside temperature is too low. The vents can be operated to 1/3 of the full capacity in warmer temperatures. Engineering solutions are being investigated on a test platform to restore the full capacity.

Replacement of the bridge crane platform has completed its design phase, construction has begun, and the implementation is scheduled for the summer of 2019. The bridge crane failure that caused the loss of a MegaCam run in May has been resolved by the complete servicing of the crane and a future maintenance schedule has been set.

Declination errors due to increased cable stiffness at decreasing temperatures are being solved by removing unused cables, which also implies rebalancing the telescope as a result of mass reduction. This work should be completed by June 2019. It was also identified that the grease of the DEC drive did not support too low temperatures. This grease was removed and will be replaced with one that should operate optimally down to -20°C.

The new TCS RBUS has passed the tests and is officially released, allowing a faster balance of the telescope.

An astrometric camera is being developed based on a Celestron 8” telescope which will be installed, aligned and tested during the summer of 2019. The expected accuracy is 0.3’’. A new guiding camera is also installed at the Cassegrain and has been used successfully since November 2018.

The old dry air compressor system represented a high risk since, of the 2 redundant compressors, at least one needed to operate continuously. A new unit was purchased and operates in manual mode since April.

Refurbishing of the aluminizing chamber is proceeding with new electrodes fabricated and tested successfully in a small chamber. They will be implemented after the next mirror coating during the summer of 2020.

Regarding software activities, the new QSO Phase 2 platform is being used for SPIRou since the instrument’s first light.

RECOMMENDATION #5: Continue working on an engineering solution to restore full functionality of the dome vents to improve image quality.

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Large Programs


SAC reviewed the CFIS LP report and noted the low ongoing and projected completion rates. Following the recently adopted completion policy for CFHT's LPs, SAC triggered a review to evaluate the situation and consider the allocation of new nights to CFIS during the period 2020A-2022A. SAC agrees with the LP team that allocated nights should be transferred from Semesters B to A to reflect the relative pressure for different semesters in CFIS. The exact weight of this balance should be worked out between CFHT and CFIS. SAC is pleased to see several publications despite the low completion rate.


This program will finish in 2019B and seems to be on its way to achieving its goals. The infrared (IR) parallax program has been running smoothly for a long time, having already produced ~100 parallaxes with errors of about 1.3 milliarcseconds, which makes CFHT+WIRCam world leader in quantity and quality of IR parallaxes. The group has started publishing papers, and one of their discoveries was the subject of a joint CFHT-Keck press release. CIPP can be expected to have a strong impact in studies of volume-limited samples of brown dwarfs and low-mass stars that will lead to estimates of the mass function near the boundary between these two kinds of objects and better understanding of the atmospheric physics at these temperatures and gravities.


SAC considered the situation of the VESTIGE LP and the low current and expected completion rates. Following the recently adopted completion policy for CFHT's LPs, SAC triggered a review to evaluate the situation and consider the allocation of additional nights to VESTIGE during the period 2020A-2022A. Nevertheless, SAC is pleased to see the steady rate of publications coming from the team despite the low completion rate.


The LP is proceeding at a good pace, with the acquisition of high-quality data. SAC considers it a positive sign that the team is expanding and is looking forward to the first publications based on acquired LP data.


SLS began collecting data in 2019A. At the time of the Users’ Meeting the PI reported 9.8 nights of validated data collected with more SPIRou runs to come in the semester. SLS was initially allocated time from 2018B to 2022A. There are two options for redistribution of the time not used in 2018B. This will either be spread across the semesters 19B, 20B and 21B or put in 2022B to extend the survey by one semester. This decision will be taken in consultation with the LP team. SAC is looking forward to receiving a more detailed progress report in future semesters.

Telescope Use and Scheduling

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

Planned runs were impacted by the crane failure in May 2019, which led to longer SITELLE and SPIRou runs, at the cost of a full MegaCam run in dark time. The consequences of this change on the MegaCam LPs, in particular, will not be entirely mitigated before the end of the semester.

Telescope pressure in 2019A from the different agencies is at healthy levels. Instrument demand in 2019A shows that SPIRou, MegaCam and ESPaDOnS are the most requested instruments. The comparatively low demand for SITELLE is a concern, though this may partly result from key science being pursued through the SIGNALS LP.

QSO and Phase 1

The QSO system continues to perform well. SPIRou was incorporated into the QSO system in 2018A, along with the new user API.

Two issues were raised related to the information provided to the agency TACs from Northstar. First, for programs with large lists of co-Is and targets, part of either the co-I or target lists is dropped when the program information is sent to the TACs. As a work-around, CFHT needs to send the necessary information to the agency TACs based on extractions directly from the data available at CFHT. The second issue relates to Canada's need to have anonymized proposals. A modification to Northstar was needed to ensure the author information is not provided to either the Canadian TACs or the CFHT staff for technical review.

2019 CFHT Users' Meeting

SAC congratulates the LOC for organizing a very successful CFHT Users’ Meeting in Montréal. Coordination with team meetings for two of the CFHT Large Programs ensured the highest ever attendance for a Users’ Meeting. SAC was impressed by the excellent science talks highlighting the productivity of CFHT and future possibilities with MSE. As lessons learned for the future, SAC found that having a very wide room with two screens was not optimal for presentation and that discussion slots with a length less than 30 minutes are not very productive. Increased participation by associate partner scientists would have been valuable.

Operational and Development Priorities:

  1. Normal operations
  2. SPIRou
  3. MSE
  4. Dome vent repair
  5. Study co-mounting ESPaDOnS and SPIRou

Next SAC Meeting

The next SAC meeting will take place at CFHT Headquarters in Waimea, November 20 & 21, 2019. A summit tour will be arranged on November 19.