87th meeting of the Canada-France-Hawaii Telescope

Scientific Advisory Council

Toronto, 21-22 May, 2015

Note: The report presented below is the public version of the SAC report as amended by the CFHT Board of Directors in accordance with the CFHT Communications Policy.

After deliberation at the Quarterly Report-II 2015 teleconference, convened on 28 July 2015, the CFHT Board of Directors, in consultation with the Executive Director, took note of the following SAC’s recommendations:

Recommendation 1 Telescope Use and Scheduling
Recommendation 2 Recording and Communication on instrument performance
Recommendation 3 Scheduling of WIRCAM
Recommendation 4 WIRCam effective hours per night
Recommendation 5 Selection of MegaCam filters
Recommendation 6 GRACES/Gemini exchange time
Recommendation 7 SNR-QSO observing mode
Recommendation 8 Operational and development priorities
Recommendation 9 Future Large Programs

Report of the 87th meeting of the CFHT Scientific Advisory Council,
May 2015

The 87th CFHT Scientific Advisory Council meeting was held in Toronto on May 21-22 2015. SAC members Hervé Aussel (vice-chair), Pauline Barmby, Magali Deleuil, Tristan Guillot, Andrew Howard, Rodrigo Ibata, JJ Kavelaars, Marcin Sawicki (chair), Richard Wainscoat, and Kim Venn attended the meeting. Wei-Hao Wang from the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan attended the meeting as invitee. During the meeting CFHT Executive Director Doug Simons, Director of Science Operations Daniel Devost, and Director of Engineering Derrick Salmon made presentations and participated in the discussions. SAC thanks Pauline Barmby and the Toronto RASC members for organizing the SAC meeting at the historic David Dunlap Observatory.

1. Telescope use and scheduling report

SAC received reports on Time Allocation and Queued Service Observing (QSO). During 2014B 24% of observing time was lost to poor conditions. WIRCam was the most affected (losing 32% of its time) followed by ESPaDOnS (28%) and MegaCam (14%). Time lost to technical problems and engineering was 14% for MegaCam (see below for details), 4.6% for WIRCam and 3.3% for ESPaDOnS. Completion rates for A programs were >85% for all three instruments. Completion rates for B programs varied: 83% for ESPaDOnS, 95% for WIRCam and only 45% for MegaCam. A program that was highly ranked by the French TAC was not observed, prompting SAC discussion around the issues of program prioritization (see below).

It appears that in semester 2014B a program that was highly ranked by a national agency TAC, and as such assumed by that TAC to be of grade-A time, was placed in grade-B time by CFHT and not observed. A similar occurrence in the ongoing 2015A semester affecting a different agency was noticed part-way through the semester and so the affected program was (re)placed in grade-A where the respective national TAC was expecting it to be. While SAC recognizes that program rankings submitted by the TACs to CFHT may have to face operational realities at the telescope, SAC feels it is important that reasons that affect the rankings expected by the TACs be discussed between CFHT schedulers and the TACs.

SAC recommends that the listing of programs assigned to A, B, and C time by CFHT be communicated back to the TAC chairs and ITAC members once these assignments are made, and that any discrepancy between TAC rankings and the CFHT QSO rankings be highlighted, discussed, and clarified before the Phase-2 tool is open to the users.

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The different Agencies obtained between 55% (for France+Opticon) and 91% (for Hawaii) of their 2014B-semester time allocation. The other major contributor, Canada, obtained 69% of its allocation. Except for the MATLAS large program, which is more demanding in terms of scheduling, programs in the LP Agency obtained almost all of their allocations (56% for MATLAS and >89% for MATYSSE, BinaMIcS, and OSSOS). SAC commends the CFHT QSO team on running operations smoothly at the telescope.

The high level of technical problems for MegaCam in 2014B was due to the degradation of the L1 coating. SAC commends CFHT staff for their dedication in trying to resolve the issue promptly and congratulates them for their success. At the same time, SAC notes that the technical problems experienced by MegaCam this semester are not documented in the instrument history web-page; indeed, this page has not been updated since 2007. SAC also notes that the PIs of programs taken between the start of the degradation of the L1 coating and the problem resolution have not been advised to pay close attention when reducing their data; that information on the availability of the new MegaCam filters and the “ear” CCDs early in the ongoing (15A) semester did not propagate to the PIs as smoothly as it could have; and that changes to MegaCam software can affect time stamps in the image headers, which can affect programs that rely on precise timing.

CFHT should maintain an up-to-date history log for each of the instruments in a public webpage where all technical problems and instrument changes are recorded promptly. During the semester, any problems or changes to the instruments should be communicated to the science program PIs in a timely fashion. This could be done, for example, by updating the aforementioned instrument web log and alerting all the affected PIs to these log changes; an email list that addresses all PIs who use a given instrument in the ongoing semester could be an effective tool in that regard. If possible, the gap in instrument records between 2007 and the present should be filled.

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SAC took note that while the amount of observing time requested on ESPaDOnS is on the rise, it has been decreasing on WIRCam, while MegaCam remains the most requested instrument. SAC notes that as a result of the decrease in WIRCam demand and the consequent infrequent scheduling of WIRCam, science programs that require cadence on this instrument have suffered.

SAC recommends that at least three WIRCAM QSO runs be scheduled each semester, even if they are of shorter length, in order to ensure the full scientific output of cadence-dependent, long-term programs being done with this instrument.

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The QSO report for 14B contained an analysis of the overheads for typical nights for each instrument when no time was lost to weather, allowing for a better understanding of the nature of the overheads. SAC thanks the QSO team for providing this information, and asks the QSO team to continue providing this kind of information in the future while maintaining in their tables the old mode of computation in order to be able to monitor long-term trends. While SAC appreciates that CFHT has to keep the agency time balance on a short-term basis, it is felt that QSO should try to explore ideas to reduce the amount of overheads, especially for MegaCam and WIRCam, as this will probably be a crucial factor for the success of the future very large programs.

Additionally, it appears that the current conversion of WIRCam effective hours per night may be too high vis-à-vis data on the instrument’s use and this number needs to be reassessed and, if necessary, updated.

SAC recommends that the number of WIRCam effective hours per night figure be reassessed using WIRCam use data over the last few years. This reassessment should be done in time for the upcoming call for Large Programs.

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2. Operational status

MegaCam suffered from major downtime in 14B due to degradation of the anti-reflection coating on the L1 lens. An attempt was initially made to clean what appeared to be an oily smear on the lens, but in the run following this operation it became evident that there was substantial contamination from scattered light in the images. The instrument was therefore immediately taken off-line. After consultation with the companies that manufactured the lens and glass, the problem was resolved by removing the anti-reflection coating with acids. Work also continued in 14B to improve the mechanical reliability of the MegaCam filter frames and jukebox.

WIRCam and ESPaDOnS operated very smoothly during this period.

SAC commends the observatory staff for their continued maintenance of these complex instruments, and especially for their hard work in fixing MegaCam and bringing the camera back on-sky in a very timely manner.

During the meeting Observatory staff voiced a strong concern regarding the dangers of changing MegaCam filters during runs, which requires dangerous work at Prime focus. The MegaCam filter jukebox is able to hold only eight filters at a time, so it is not possible to offer all the available MegaCam filters without undertaking this risky maneuver.

SAC recommends that the filter selection offered to MegaCam users be rationalized. Programs should use the new filter set, unless a strong scientific case is made in the proposal for the need of the old filters. SAC also recommends that the old filters be decommissioned in the medium-term and not available in semester 17A and beyond. The CFHT user community should be informed of this policy before the 16A proposal call.

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3. Development status report


SAC was informed that final testing issues that had delayed shipment of SITELLE have all been resolved and SITELLE shipment is now waiting for coordination with CFHT. Renovations needed to accept SITELLE have been completed and CFHT is ready for the instrument’s arrival. First light and commissioning is expected beginning in August 2015 or perhaps even in late July. The Science Director is the SITELLE Project Scientist at CFHT. The SAC encourages the CFHT to find additional support for the SITELLE user community by appointing an Instrument Scientist.


Investigations have been made in order to reduce the readout time and also made the time stamp more reliable. Replacement of the ADCs used to digitize the video signal from the CCDs and amplifiers appears to be a promising solution and new ADCs should be tested.

All of the new filters are available since January 2015. The new ultra-broad band filter (gri) is expected to be delivered soon.

SAC thanks the CFHT staff for the work they have done in recent months on MegaCam and encourages them to continue their efforts at improving MegaCam even farther.


Important effort has gone into the documents in preparation for the forthcoming mid-term review that will take place 15-17 June 2015 in Toulouse. On-sky tests of the guiding IR camera procured by ASIAA have been performed in April 2015 and have demonstrated its quality. SAC’s main concerns are to do with the detectors as there is still no clear information on price or availability at Teledyne; these are two critical points that may impact the overall development of the instrument. SAC encourages CFHT staff to continue at closely following the instrument development and to look for solutions for securing engineering-grade detectors for testing and development purposes.


The CFHT SAC was pleased to hear that GRACES has proven to be popular during the most recent Gemini proposal call. CFHT is completing construction of a cold-room to enclose ESPaDOnS, easing its use in GRACES mode. SAC discussed the CFHT/Gemini time trade and how best to utilize this time. The Executive Director suggested that this time be banked until a sufficient pool is available to allow a significant impact in the community and SAC agreed with this suggestion.

SAC recommends that current GRACES/GEMINI exchange time be banked until enough time is available for CFHT to run a multi-night mini-queue on Gemini. The process for selecting proposals will be discussed at a future SAC meeting.

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The SAC also heard that the OPERA software is nearly ready for use and encourages CFHT to complete this important open-source software package.


SAC was pleased to hear that the MSE project office is now taking on more of the workload for MSE efforts. SAC is encouraged to hear that CFHT is advertising for a System Scientist to support the MSE Project Scientist role. SAC members agreed to forward this advertisement to their various national distribution lists.

SAC is pleased to hear that building of the MSE collaboration has been positively received by prospective partners. SAC was informed that interactions with China concerning MSE have been very positive. There is time pressure coming from the Chinese funding cycle and SAC urges the MSE project to operate in a mode that enables it to be ready to present a project proposal that will meet the requirements of the various funding timelines. Additional interactions with India will be occurring over the summer. SAC looks forward to hearing about further MSE partnership and project progress at our next meeting.


SAC received a presentation on the status of the SNR-QSO process. The CFHT is enthusiastic that SNR-QSO will result in improved observing efficiency. While generally very favourable towards SNR-QSO, SAC is somewhat concerned that this new observing mode may penalize some observing strategies. Consequently, SAC urges CFHT to make SNR-QSO available in a way that does not penalize programs for which this mode is inappropriate. PIs should not be required to make use of this mode when they feel their observing circumstances make SNR-QSO inappropriate.

The SAC endorses CFHT’s proposal to return observing time saved to the general pool for further agency balancing. A report on how SNR-QSO has been used should be prepared for each SAC meeting.

The process of implementing SNR-QSO must include a tool that converts the SNR computed for various source profiles present in the CFHT ETC system into a point-source equivalent value that SNR-QSO will use. SAC suggests having the equivalent value be reported via the ETC web pages.


The SAC recommends that CFHT proceed with making SNR-QSO the default observing mode. Users should have to justify opting-out of SNR-QSO on scientific grounds. The user community should be informed of these changes in advance of the next proposal cycle.

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4. Operational and development priorities:

SAC received a presentation of the technical activities report by Derrick Salmon. SAC extends its thanks to the CFHT staff for achieving very significant progress on a number of important projects in the past six months.


SAC recommends the following work priorities for the coming months:

    1.    Normal operations
    2.    SITELLE commissioning
    3.    OPERA for ESPaDOnS
    4.    Comissioning and characterization of the ultra-wide MegaCam filter
    5.    MegaCam readout controller improvements
    6.    Finalizing WIRCam nonlinearity characterization
    7.    Development of the WIRCam data pipeline
    8.    Mirror cover modifications plan for IQ improvement

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5. Ongoing Large Programs

SAC reviewed status reports from the BinaMIcS, MATLAS, MaTYSSE, and OSSOS Large Programs. SAC thanks all four teams for preparing thorough and comprehensive reports on their progress.

The SAC agrees that BinaMIcS, MaTYSSE, and OSSOS programs are making good progress, and has no concerns going forward. Each of these Large Programs is getting its data and making good progress as monitored by their time allocations, papers, and conference presentations. There are no serious issues with observing, scheduling, or data reductions. The PIs for these programs are also doing a good job of keeping in contact with CFHT, and therefore the SAC supports that these programs continue with their excellent work.

SAC feels that the MATLAS project is making good progress despite having had a relatively low completion rate due to a number of factors, including weather, instrument failure, and competition from other programs. SAC is pleased to see science results coming out of MATLAS in the form of presentations and publications.

The SAC agrees with the MATLAS team’s contention that the observing condition constraints are not particularly stringent; we believe that one reason why we hear from CFHT staff that MATLAS is hard to schedule is that they are comparing it to LPs using ESpADoNS, which have particularly relaxed constraints. MATLAS is in more direct competition from OSSOS, which has time constraints due to the nature of that project's science. The combination of the higher rank of OSSOS by the LP TAC and the RA-constrained nature of the MATLAS observing is the main cause of lower completion for MATLAS.

The SAC appreciates the MATLAS team’s comments that relative priority of LPs and PI programs should be reconsidered, and this formed part of the SAC discussions about the next LP call. However, SAC believes it is not appropriate to change the balance for presently-running LPs. The MATLAS team’s report raised the issue of poor communication with CFHT regarding the change in filters and MegaCam coating problem. SAC agrees that this requires attention from CFHT (see Recommendation #2).

6. Future Large Programs

SAC noted the Board endorsement of the proposed staged plan of future LP for 2017A and beyond, and has discussed how these programs would be selected. The Hawaii Agency requested the minimal amount of time of a large program to be lowered in order to allow them to lead a multiagency LP without having to commit more than 30% of their time to this endeavor. While SAC is thrilled by the University of Hawaii interest in Large Programs, it is felt that the goal of the 2017A LP call is to enable truly large programs, and for this reason would waive the 100 nights requirement for UH-led Large Programs only.

SAC also discussed issues related to the selection of the new LPs, building on its earlier discussions in this regard. SAC’s recommendations in this area are contained below.


CFHT should issue the first of the two staged Large Program calls no later than 30 June 2015.

Each proposing team should submit by 7 September 2015 a non-binding one-page Letter of Intent (LOI) containing a list of co-investigators and an abstract of the science case.

Full LP proposals will be due 31 January 2016. Proposals can compete for part or all of the 429 nights set aside for LPs by the Canada and France Agencies, plus possibly for additional time from the other partner Agencies. LP proposals should request at least 100 nights each, with the exception of LPs led by UH PIs, which can request a minimum of 50 nights. UH-lead proposals here are defined as proposals with a UH-based PI and requesting at least 50% of their total time from the Hawaii Agency.

Selection of successful LP(s) will be done by an LP TAC as follows. All LP proposals will be discussed and ranked by the agencies’ TACs along with their regular 2016B PI proposals, and representatives of the TACs whose agencies are participating in the LPs will meet as the LP TAC for the final selection of the successful LP(s)

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7. External initiatives

SAC heard from the CFHT Executive Director of two external instrumentation initiatives. The first of these is from Chinese astronomers and concerns the construction of an AO instrument for CFHT. The E.D. advised this team to develop a ~10-15 page proposal describing the instrument and various relevant aspects of this initiative. SAC is looking forward to seeing this document when it becomes available. The second relates to the possibility of transferring the FMOS infrared multi-object spectrograph from Subaru to CFHT. SAC feels that this possibility should be studied, resources permitting, to assess its feasibility in terms of hardware modifications and likely cost.

8. Next Users' Meeting

The next CFHT users’ meeting will be held in early May 2016. SAC thanks Tristan Guillot for offering to host the meeting in Nice, France.

9. Next SAC Meetings

The 88th SAC meeting will be held on 2015 November 18-20 in Waimea.

It is expected that the 89th SAC meeting will be held in May 2016 in Nice, in conjunction with the CFHT users’ meeting.