91st Meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

Victoria, 4-5 May, 2017

After deliberation during its Quarterly Report-II 2017 teleconference, the CFHT Board of Directors, in consultation with the Executive Director, took note of the following SAC's recommendations:

Recommendation 1 SPIRou, Acceptance Test List
Recommendation 2 SPIRou, Large Program Call
Recommendation 3 Time Allocation - Conflict of Interest
Recommendation 4 Shutter Open-Close Times
Recommendation 5 Instrument Web Page Reading
Recommendation 6 CFIS Large Program
Recommendation 7 Mirror Coating
Recommendation 8 GRACES - Time Allocation
Recommendation 9 Automated Service Observing
Recommendation 10 Daytime Observations

Report of the 91st meeting of the CFHT Scientific Advisory Council,
May 2017

The 91st CFHT Scientific Advisory Council meeting was held in Victoria on May 4-5, 2017. SAC members Hervé Aussel (chair), Stéphane Courteau, Magali Deleuil, Tristan Guillot, David Lafrenière, Nicolas Martin, Roberto Mendez, Kim Venn, Richard Wainscoat, and Chris Willott (vice chair) attended the meeting. Yen-Ting Lin from ASIAA attended the meeting as an observer. The CFHT Executive Director Doug Simons, the CFHT Director of Science Operations Daniel Devost, and the CFHT Director of engineering Derrick Salmon participated in presentations and discussions. Kanoa Withington and Claire Moutou participated remotely in some of the discussions.

SAC heard a presentation by Executive Director Doug Simons describing the possibility for CFHT to partner with UH and EAO for the management of UKIRT at no cost to CFHT. SAC has discussed and views this option positively. SAC sees likely scientific gains and observing opportunities in the future for the CFHT community. SAC supports the MSTAR and other outreach initiatives and cooperation between organizations on Maunakea. SAC looks forward to receiving more detailed information before expanding the scientific uses or applications of the CFHT community at UKIRT. It is expected that SPIRou will remain on CFHT for at least the duration of the upcoming Large Programs.

Maunakea Spectroscopic Explorer

SAC commends the MSE team for the impressive progress leading to the preparation of a construction proposal.


SAC heard a presentation by Driss Kouach with participation by Jean-François Donati and René Doyon about the SPIRou status. Integration is well underway at IRAP, and SAC was presented with a preliminary plan to conduct acceptance testing over the summer with the H2RG detector for a shipment in September 2017 to CFHT. Meanwhile, work is progressing at CFHT for the installation of the instrument in the coudé room. SAC commends both the SPIRou team and the CFHT staff for their effort for a timely arrival of SPIRou at the telescope. SAC was pleased to learn that the H4RG detectors would be delivered in the fourth quarter of 2017 for a final integration at CFHT and a final acceptance and commissioning with the science grade array in March 2018.

SAC recognizes the Board of Directors’ desire to start the scientific exploitation of SPIRou as soon as possible with a large allocation of time, and recommends the following steps to be taken in order to allow the opening of a Large Program call for proposals where SPIRou would be offered.

RECOMMENDATION 1: A clear acceptance test list must be agreed upon between SPIRou and CFHT, wherein preliminary tests that can be conducted before the end of July are clearly identified. These tests must allow the publication in September 2017 on the CFHT web site of the expected on-sky capabilities of SPIRou.

SAC will convene via a special video-conference to evaluate the preliminary acceptance tests no later than early September to recommend or not the launch of the LP call outlined below.

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Next Large Program call for proposal.

RECOMMENDATION 2: Pending the results of the SPIRou preliminary acceptance tests outlined above, SAC recommends for a Large Program call to be issued in September 2017, with letters of intent due November 1, 2017 and proposals due March 1, 2018 for a selection at the May 2018 SAC meeting. The amount of time offered on all CFHT instruments shall be approximately 400 nights spread over semesters 2018B to 2022A, with a minimum of 300 nights using SPIRou, and a minimum amount of 50 nights per proposal.

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SAC expects the commissioning of SPIRou to take place before its May 2018 meeting, and that a better on-sky knowledge of the capabilities of the instruments shall be available at the time of the LP selection. Proposals using SPIRou must clearly identify what capabilities of the instrument they rely on.

This call follows the scheme exposed in recommendation 6 of the November 2014 SAC meeting (http://www.cfht.hawaii.edu/en/science/SAC/reports/SAC_report_Nov14.php#Rec6). The current LPs executed at CFHT will have their data acquisition rate reduced from 2018B onward and proceed until 2021A, therefore having an unchanged total time allocation, while the new LPs would start at a slower rate in the period 2018B-2021A and use all the LP time available in 2021B-2022A.

SAC recommends that a similar selection procedure as the 2016 LP call be followed:

  • SAC expects CFH agencies to assign chairs who are not strongly conflicted with the Large Programs.
  • The Canada TAC Superchair and the France TAC Chair (the ‘chairs’ hereafter, or non-conflicted substitutes) will select a non-conflicted primary reviewer for each LP proposal in their respective TACs.
  • The primary reviewers will propose the names of a few potential non-conflicted and specialised external reviewers to the chairs.
  • The chairs will contact external reviewers to secure three reviewers for each LP proposal, and will request from them written reviews.
  • The external reviews, along with CFHT technical reviews, will be made available in a timely manner to each Agency’s TAC. This will include TACs of the associate partners for LP proposals that request time from these Agencies.
  • Each agency TAC will rank the proposals based on their scientific merit, as they do for PI proposals each semester, and will indicate a cut-off point in its ranking beyond which proposals are not to receive LP time from that Agency. This ranking will be done in advance of the May 2018 SAC meeting and will be provided to the LP Panel (described next) along with any relevant instructions.
  • An LP Panel, constituted of 3 representatives of each C and F TACs (selected by the C and F TACs, and including these TACs’ respective chairs) one H TAC representative (selected by the H Agency), and three external members selected by CFHT, will merge the TAC-ranked lists into a single list, taking into account operational considerations. This merging will be done in advance of the May 2018 SAC meeting.
  • SAC will review the ranked LP list during its May 2018 meeting, recommend the global number of nights to be assigned to LPs, and transmit this information along with the TAC ranked list to the Board for approval.

Conflicts of interest

SAC reviewed the conflict of interest document that was used for the selection of LPs in May 2016 and endorses its content. The document is provided as an annex to this report.

RECOMMENDATION 3: SAC recommends implementation of this conflict of interest document by all CFHT evaluating bodies (TACs and SAC).

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Development Status Report


A first data cube at R=9000 has now been realised; this is a significant achievement. However, the center-to-edge image quality is still not optimal and causes a 50% area loss. This limits some of the science for which SITELLE can be used, and appears to be reducing demand. This appears to stem from the focal surface deviating from the specifications: the cause for this should be investigated further.


The SAC learned that MegaCam FAST was installed in January 2017. This saves almost 7 seconds in readout time, and reduces the time between successive exposures by approximately 5 seconds. In the four dark runs since usage began, the fast readout mode has saved more than 1 night total in observing time. CFHT believes that they can improve the time savings to 8 seconds per exposure by replacing the detector host computer. The SAC is very pleased with the increase in observing efficiency that has resulted.

The SAC also received a report that evaluated the approximately 120 seconds presently needed to exchange filters, and whether this could be reduced to further improve efficiency. The SAC endorses the careful approach being made in evaluating possible improvements in filter change speed.

The SAC also discussed problems with exposure time stamps reported in MegaCam headers, and learned that times written in the header do not correspond exactly to the moments when the shutter opens and closes, and that differences in header keywords between reported and actual times of up to 6 seconds are occurring. The clock that the shutter refers to is a relative clock and not an absolute clock. The MegaCam shutter takes 1 second to open, and 1 second to close (and therefore, the shutter open and close time are dependent on location across the array). CFHT reported that a sensor near the shutter can be adapted to make a much more accurate reporting of shutter open and close time utilizing an absolute clock. Accurate timing is important when reporting astrometry of fast moving Near Earth Objects, and may also be useful for other scientific applications such as rapidly rotating objects and transient phenomena. The SAC believes that trying to report a time accurate to 100 ms is adequate for most scientific applications. It will be important to specify where on the array the reported time is referenced to (e.g., does it refer to the center of the array?) The SAC reminds CFHT that it should communicate to observers when changes are made that may affect timing.

RECOMMENDATION 4: SAC recommends that accurate timing information for shutter open and close times be implemented and recorded in MegaCam image headers.

SAC is concerned that Megacam’s recent improvements (fast readout) were not documented on the instrument web page.

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RECOMMENDATION 5: SAC reminds CFHT that all significant changes to instruments be reported on the instrument web page.

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Investigation for a new cryostat window for MegaCam

CFHT Director of Engineering presented SAC with a report on potential MegaCam u-band throughput improvements to be expected from using a new BBAR coating of the cryostat window and possibly replacing the Image Stabilizer Unit (ISU) window. It is expected that the new setup would lead to a 7/1.5% improvement to the throughout in the u/g band for an order-of-magnitude cost of ~60k$ and minimal losses in the throughput of the redder bands. Companies approached by CFHT raised concerns about meeting the required specifications. SAC thanks CFHT for exploring the benefits of these changes.

RECOMMENDATION 6: Given the small benefit of this change and the risk it will significantly affect the homogeneity of the ongoing Canada-France Imaging Survey (CFIS) Large Programme, SAC recommends the change not be pursued at this time.

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Operation Status Report

Mirror cover for IQ improvement

The results of the pre-conceptual design review on the replacement of the primary mirror cover indicate that this would be a major undertaking requiring many years to complete and a dedicated project manager. A very crude assessment of the impact this change would have on image quality was stated as about 0.05", which is significant. Given the scope of the work that such a replacement would entail, SAC encourages CFHT to carry out either a water tunnel test or a computed fluid dynamics simulation to assess more robustly the improvement in IQ that could be achieved by this change before pursuing the idea further.

Mirror Coating

In light of the colour-dependent reflectivity degradation observed in MegaCam zero-point data and the results of the impact study of switching to a 2-year re-coating cycle, which indicate a potential net gain of 4-7 observing nights per year compared to the current 3-year cycle, SAC believes that the proposed switch is worth implementing. However, given that a re-coating is already planned for this July, no decision has to be taken in the short term. In the meantime, other options should be studied to mitigate the mirror reflectivity degradation. In particular, CFHT should investigate if the coating process they use could be improved, and the extent to which washing the mirror restores reflectivity.

RECOMMENDATION 7: SAC recommends that CFHT explore the possibility of physically washing the mirror before the last MegaCam run prior to the planned re-coating of the mirror in July, as this would allow measuring the impact of washing the mirror on the photometric zero points.

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ESPaDOnS worked well this semester in the two amplifier detector readout mode, with the benefit that read times are now faster. SAC thanks Jean-François Donati for providing an updated version of the Libre-Esprit pipeline to account for the two amplifier mode for continuous and efficient data processing. A change in the detector power supply temporarily raised the bias levels, but this was quickly fixed by removing a ground wire from the main input to the power supply. Remote sensing of the air condition in the coudé room and of the air supply on the ESPaDOnS optical bench were installed.


There were no issues with WIRCam this semester. The vacuum in the cryostat has been holding for weeks.

Telescope use and scheduling

SAC was presented with detailed reports on telescope time allocations and queue operations. The subscription rates from the agencies remain at healthy levels in 17A and 17B showing that the capabilities of CFHT are still in demand from the community. As expected, MegaCam and ESPaDOnS continue to be the instruments with the greatest demand and the highest allocations. The allocated time for WIRCam has increased in 16B and 17A compared to the low level of a year earlier. SAC notes that demand for SITELLE was high in 17A with over 200 hours requested, but the acceptance rate of only 15% means only a small amount of allocated time. There is no obvious single reason for such a low acceptance rate and these rates do fluctuate from one semester to the next, but this is an area SAC will keep an eye on in the future. SAC is worried by some significant discrepancies between requested and required exposure times on some proposals and suggests proposal PIs be given the opportunity to contact CFHT staff before proposal deadlines to ensure their requests are accurate.

The high subscription rate from Taiwan is very positive. SAC encourages efforts by CFHT staff to reach out to the NAOC community to explain the capabilities of the observatory.

Despite the May 2017 recommendation #2 of SAC that all TACs should “meet early enough so that programs can be transmitted to CFHT by May 1” the Canadian TAC had not met before this SAC meeting, so no information on 17B allocations was available for SAC to consider. We reiterated this point to the Canadian TAC meeting scheduler and expect this problem not to occur in future semesters.

SAC continues to be concerned that no Canadian Time Allocation Committee member is on SAC, and suggests this issue be resolved before the next time that Large Program proposals are reviewed.

SAC is pleased that GRACES is in high demand and that the Gemini time process is improved with Canada and Hawaii rolling the time into their own Gemini allocations. However, there is still uncertainty about the process by which French programs at Gemini will be executed, and uncertainty regarding distribution of payback time across Gemini North and South. SAC requests that CFHT continue to investigate options for optimizing French observations with Gemini.

RECOMMENDATION 8: SAC recommends that CFHT clarify with Gemini the aforementioned points. SAC recommends to offer in 2018A an amount of nights such that the accumulated number of nights obtained through the Graces agreement remains constant.

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QSO operations appear to be working well and SAC is encouraged by the results of extending the QSO-SNR program to Espadons, where the real time exposure meter makes it easy to determine when to terminate observations early.

Automated Service Observing:

SAC is very interested by the possibility to implement an Automated Service Observing at CFHT in replacement to the currently manually prepared nights scheduling. The preliminary study presented to the SAC was carried out in the context of future SPIRou observations but would clearly benefit other instruments and the whole CFHT community, including even future MSE observations. The report is clear, lists the advantages on both technical and scientific sides, and proposes a study plan. The latter includes the development of a simulation tool, based on existing experiences in others observatories, to assess the gains in more details and prepare the possible subsequent implementation. An estimate of the manpower needed is also provided. SAC acknowledges the strong potential of such a tool that would allow to maximize the science return, optimize the use of telescope time, and free CFHT astronomers for other tasks.

RECOMMENDATION 9: SAC recommends that CFHT, together with members of the SPIRou team, explores the possible implementation of such a tool in more details, and allocates the needed support of the software team as soon as their current operations on the new PH2 API architecture and the database will allow it.

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Observations are currently normally performed at CFHT between nautical sunset and sunrise, but daytime observations have been exceptionally taken with ESPaDOnS for the study of Venus. With the arrival of SPIROu on the telescope, the case for late evening or early morning observations when the sun is up will become more pressing, as these instruments can put these conditions to a good use. However, such observations present a greater safety risk for the telescope, and can also disrupt the day crew mission.

RECOMMENDATION 10: SAC recommends that CFHT study carefully the trade-off between risk and advantages of conducting day time observations and look forward for the conclusion of this study to be presented at its next SAC meeting.

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Large Programs


SAC is pleased to learn that the OSSOS dataset exceeded the team expectations, that all sky blocks have been observed with 100% completion, and that the team was able to recover objects for the arc lengths needed to secure high-precision orbits. The team has been extremely productive with this dataset, and the SAC is pleased to see the timely publication of their scientific results


The program is close to completion in terms of observations. Analyses of individual targets are still on-going with some papers already published and others in preparation. The statistical analysis is expected to take place once all targets analyses are complete. SAC encourages the BinaMicS team not to delay the publication of the survey paper, despite the human resource issue that the team underlines again. One way to mitigate this would be that members of the LP team increase their personal participation in the data analysis. The SAC also reiterates that the data archive of the reduced BinaMicS spectra, whose current status is not mentioned in the report, should be made available to the community.


The MaTYSSE LP is completed, but the team expects the analysis of the data to continue for at least two years. The program has obtained scientific results in both stellar and exoplanet science. It has provided for the first time the large-scale magnetic topologies of young stars. It has shown that tomographic techniques can be used to remove activity jitter to attain a radial-velocity precision of a few tens of m/s, allowing the detection of two hot Jupiters around T-Tauri stars. 11 papers from the team are submitted, in press or accepted. In addition, 1 paper using the LP data has been published by a different group. These results are outstanding and SAC looks forward to the next results, including the estimation of whether hot Jupiters are significantly more frequent around T-Tauri stars than around main-sequence stars.


SAC applauds the timely publication of a survey paper. However, a discussion of ongoing analysis, expected science goals, advanced data availability plans (e.g. through web dissemination) and a list of expected publications would have been appreciated.


SAC is pleased by the scientific output of the HMS Large Program and the continuous stream of published and submitted papers that stem directly from the LP data. SAC is looking forward to the results of the upcoming analyses and is relieved that the team expects to fully reach the LP’s primary goals despite weather losses.

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Operational and development priorities:

SAC, after discussion with the Director of Science Operations Director of engineering, is proposing the following ranked list of priorities:

  1. Normal operations
  2. SPIRou
  3. PH2 improvement
  4. SITELLE performance improvements, operational issues
  5. Megacam observation efficiency improvement and shutter timing

Next SAC Meeting

The 92nd SAC meeting will take place, in Waimea 20-21st November with a visit of the summit either on the 19th or on the 22nd of November.



Rules of conflict of interest for CFHT Committees.

This set of rules is inspired from the Rules for Dealing with Conflicts of Interest on ESO Committees (attachment 7 to ESO/Cou-1040)

  1. A conflict of interest arises when the Committee is called up to make a decision on a matter in which a member, or her/his institution, or a closely connected associate, or her/his immediate family has a professional, financial or commercial interest.
  2. It is the responsibility of all members of the Committee to report all their own actual or potential conflicts of interest to the Committee. All members must declare any potential conflict of interest to the committee before the start of discussions.
  3. Committee members shall declare to the Committee any actual or potential conflict of interest in any item of the agenda immediately they become aware of it.
  4. The committee will evaluate the impact of the stated conflicts of interests and decide, without the potentially conflicted members participating to the vote, whether to consider the committee members as actually conflicted. In the event of a tied vote, the decision of the Chair shall be final.
  5. In any situation dealing with finite resources, some decisions have implications for all other decisions. If an actual conflict of interest as determined by rule 4 arises, the Committee Member may be requested by the Chair of the Committee either to withdraw from the discussion of that item, or to participate in all or part of the discussion, but should a vote be called, the conflicted member shall not participate to the vote.
  6. Should the Chair be required to withdraw from a discussion, the Committees members shall agree on one of their members to act as temporary chair for the discussion of that item.
  7. Should a conflict of interest be discovered after a vote or recommendation has been made, the chair shall propose to the committee that either:
    1. the vote or recommendation should stand with the vote of the conflicted member converted to an abstention.
    2. the vote or recommendation is declared null and void, and shall be revised with the conflicted member withdrawn.
  8. Any deliberate failure to report a conflict of interest shall be reported to the person or body appointing members to the Committee, and this person or body shall decide on the actions to be taken, and inform the Committee.

Notes on rule 1: in the case of Large Programs, an actual conflict arises when the Committee Member is the Principal Investigator or co-Investigator of a Large Program proposal. Potential conflicts arise when the Committee Member is part of an institution, or closely related to (professionaly or privately) with the PI or a some co-Is of a proposal. The importance of the conflict depends on whether the proposing persons are within the same group, or on distant colleagues and is left to the appreciation of the committee under rule 3.
Note on finite resources (rule 5): in the case of Large Programs, finite resources are the available amount of dark, grey and bright time.