Report of 55th CFHT SAC Meeting

LAS, Marseille, May 3-5 1999 

The meeting was attended by all SAC members with the exception of J-G Cuby, who sent in apologies and submitted written comments on agenda items. CFHT were represented by P. Couturier, D. Crabtree, D. Salmon, and C. Veillet. Incoming director G. Falhman also attended. New SAC members S. Lilly and M. Pierre were welcomed as replacements for G. Joncas and P-O Lagage.

The following agenda items were discussed. Input documentation to the meeting is given at the end of this report. CFHT technical reports were also provided to the committee, and these are also given at the end of the report. SAC also reviewed an interim report from W. Grundmann on his study of a swinging secondary mirror structure.

SAC Agenda

  1. CFHT Technical reports from CFHT: particular interest in
  1. Observing
  1. Future instruments and budget (CFHT)
  1. Megacam and beyond
  1. Other items

Technical Activities

Memos Submitted to SAC


Activities since last SAC meeting.

SAC was involved in email discussions on several topics between meetings. The SAC chair also attended the CFHT Board of Directors (BOD) meeting in December 1998, and met with L. Vigroux and P. Couturier in April 1999.

  1. J. Hutchings and D. Crabtree drafted the following set of TAC guidelines at the request of the BOD. These were sent to the agency TAC chairs.
  2. SAC advised that the CFHT pursue the option of trading observing time with Taiwan (and other suitable agencies or institutes) for funds that would be used towards the proposed WIRCAM (Wide Field Infrared Camera) for CFHT. The following recommendation was sent to the BOD.

Reccomendation #1:

  1. The principle of selling telescope time for WIRCAM is acceptable as the only way of getting this instrument in the timescale required. The Taiwan deal comes under this category.
  2. The suggested time sold of 5% over 4 years is a maximum for $2m. We do not support funding the whole WIRCAM for more than 10%/year. We urge CFHT to ask for numbers nearer the $50K per night recommended by SAC, considering the value of the site, instrumentation, staff, and capability of CFHT as added value.
  3. The deal should also include Taiwan-paid personnel to be posted to CFHT and other CFH institutes, to help us with operations and WIRCAM work. The deal would be more acceptable if it included agreement to collaborate with Taiwan astronomers on some fraction of the sold nights. (In any case the agreement needs to specify how the nights are distributed and assigned, given the scheduling problems we already face with the existing partners.)
  4. The agreement may be renewed if it is successful and particularly if it adds further funding towards WIRCAM. Such extension cannot be decided yet. It must also depend on other partnerships and which work best. This would encourage Taiwan to be a good partner.
  5. All the money from the deal must be spent only on WIRCAM. In particular it should not be used for general operations or other instrument overruns.
  6. We strongly prefer that the deal should begin only when we have full funding assured for WIRCAM, or be subject to cancellation within this calendar year if not. The money must be paid in full before the 4 years in order to enable WIRCAM contracts to be let. Other WIRCAM partners must be identified immediately and urgently.
  7. The time sold should come off the 3 CFH partners' time in the usual proportion. If we have a formal collaboration deal, the TAC process should keep track of how Taiwan-collaborated nights are used among the CFH communities, and report to SAC.

We do not anticipate that the above response will result in the deal breaking down. If it does, SAC should be consulted, in case we wish to advise again on the basis of what happens. If Taiwan have changed their price below our minimum acceptable, we should terminate the discussion.

SAC also urges that the WIRCAM working group be active in any partnerships or deals that involve design, performance, building, and schedule for WIRCAM. It may be necessary to rotate some membership to make the group more active.

  1. SAC advised the CFHT that Redeye should be repaired only for use as FTS BEAR dedicated detector, and that this should not significantly impact the effort and schedule for the CFH12K and CFHT-IR cameras.
  2. SAC reviewed and approved the CFHT plans for electronic proposal submission and queue scheduling. Several SAC members took part in testing the electronic submission package.
  3. SAC developed and submitted the following detailed plan for a joint Canadian-French TAC, as requested by the BOD, following the SAC recommendation to form such a committee. (This proposal was not supported by all BOD members and has since been abandoned. The SAC chair noted to the BOD that several of the detailed points in their correspondence on the subject reflected inaccurate information on current TAC procedures.)

SAC proposed joint Canadian/French TAC for CFHT.

  1. SAC proposes a joint Canadian-French CFHT TAC as recorded in the SAC report from the Oct 1998 meeting and discussed at the Dec 1998 Board meeting. No start date is mandatory but we wish to begin as soon as possible. The Canadian side would like to synchronise with the first Gemini TAC who will be needed for 2000 II. Thus we propose a joint TAC who would first work together in March/April 2000 for 2000-II semester time. Initial membership should be planned during 1999.
  2. In view of the total number of proposals from both agencies, it is desirable to split into two ~equal subgroups by science category. We propose this be very generally `extragalactic'and `stellar' and that each semester the dividing line be drawn so as to give each group about the same number of proposals. This split should also ensureapproximately equal distribution between Canadian and French agency proposals and TAC members between the subgroups.
  3. The TAC should consist of 5 French and 5 Canadian members, who serve default terms of 3 years, with evenly distributed timing of replacements. In view of unpredictable conflictsand changes, it may be best not to have rigorous rules on terms, but only to state that no member may serve more than 3 years.
  4. The initial joint TAC should consist largely of current CTAC and CFGT members to ensure corporate memory. This may involve `retiring' some CFGT members and one CTAC member to reduce the number to 5. Replacements would be appointed by national agencies but should be guided by recommendations from the TAC, with comments by SAC, to ensure proper spread of expertise and experience. SAC should have input into the initial makeup of the joint TAC.
  5. The joint TAC will be organised by joint chairs from Canada and France. They will split the proposals between the two TAC science groups and assign referees. Support staff at HIA and in France will assist with sending proposals to referees, distributing replies, etc. As at present, proposals may be submitted to either agency in English or French. Considering that many French agency proposals are submitted in English, language skills of TAC members should not be a new issue.
  6. Proposals should be sent to outside referees, following the general process of CTAC. This process or the use of referees may evolve with time, but most Canadian proposers at present are anxious to maintain this. (It is however debated how much difference this makes if the TAC group has the right size and experience.) Referee comments are sought as expertadvice to aid but not determine TAC rankings.
  7. Meetings should initially be face to face, to enable good working relationships to evolve. In order to reduce travel costs it may be possible to hold some meetings by video link once the process is working well. Since the change will reduce French membership more than Canadian, and travel costs may be an issue, it may be that holding joint meetings in Canada would keep the costs close to what they currently are on each side. In any case, meeting venues should be chosen to minimise travel time and costs.
  8. The two TAC groups should meet together and emerge with a joint ranking of all proposals. In each group, each member will rank all proposals in his/her group unless there is a conflict of interest. Each proposal will have a lead reviewer. The two TAC subgroups will then get together to produce an overall ranked list. The final ranked list may be split into French and
    Canadian agency proposals, or at least contain enough supported proposals to oversubscribe the agency time and dark/bright time by the required amount (see the TAC guidelines of Crabtree and Hutchings, Dec 1998).
  9. The final `CFHT TAC' whose role is already defined in scheduling telescope nights in detail, will work in the usual way, with representatives of all 3 agencies from the UH and joint TAC. Thus, it will be necessary to make sure that 1 or 2 SAC members from each agency are also members of the joint TAC. UH may participate in joint proposals by informal additional arrangements.

  1. The following is the agreement reached by Vigroux (on behalf of CEA and Terapix), Hutchings (on behalf of SAC), and Couturier (on behalf of CFHT) regarding the Megacam survey time science programs.

The SAC concerns as noted in the last meeting report are summarised as:

Scientific programs with Megacam

The following describes a process for the use of Megacam that represents a merging of the approaches advocated by the CFHT SAC and CEA.

As an initial frame of reference, the MOU between CEA and CFHT appears to be acceptable and states that a minimum of 6 weeks per year be used for survey programs over a period of 5 years. The CFH agencies will be asked to approve that this time be allocated from their shares of CFHT time. Non-participating agencies will not have access to survey data, except via the usual route of access to public archival data. It is also possible that the minimum survey program time could be accomplished by using more time for fewer years. It is desired that this program should be completed on the CFHT without interruption or further major alterations to the telescope. It is currently hoped that Megacam will begin full scale science operations in 2001 semester II.

1. A survey working group should be established soon, preferably in the summer of 1999, to begin planning of an initial suite of programs that will account for a nominal 2/3 of the proposed Megacam survey program time. This group will be composed of one member each from CEA and Terapix, and suitably expert astronomers from the CFH communities. The group will be selected from volunteers to respond to a call for survey project ideas issued by the SAC in June 1999. The group will be tasked with a document produced by SAC that will include the following actions.

Define the filters and observing strategies for a core suite of survey programs. These will take into account other survey programs under way and planned, and also plan image quality, data processing, sky areas, and observing strategies. In particular, the observing strategies should consider observing date windows, image quality requirements, and the advantages of queue or shared night scheduling, and the optimum way to complete programs over 5 years or less. Techniques for observing and making use of transient targets such as Kuiper Belt objects or Supernovae should also be planned.

The working group will be expected to operate until the core programs are under way, and to be involved in them.

This work is considered to be of some urgency and should be under way during 1999.

2. By the start of Megacam operations (exact time TBD), the actual survey programs will be peer reviewed by an international committee. New programs and variations on those planned will be possible, but must be compatible with the overall observing plan as outlined by the working group. Further new survey projects will be considered and reviewed in similar fashion throughout the Megacam survey program.

In order to recognize and compensate the CEA contribution to the instrument, the peer-review team will be given guidelines on the requirement to include CEA participation in a suitable set of the survey projects.

Megacam will be available for small projects approved for the use of non-survey time available through the agencies in the usual way. These data will receive only CFHT pipeline preprocessingas noted below.

3. CFHT will apply no more than pipeline pre-processing of individual images. Terapix will then apply additional processing and source measurement within the datasets of survey programs. The fully processed data will be deposited in an archive accessible to the participating agencies as they are completed. Individual survey teams will participate in processing as needed. Access to data outside the participating agencies will await the usual 1 year delay before release.

Proposals for immediate access to the (not fully processed) data for uses other than those in the main survey goals, will also be peer-reviewed and approved by the international committee.

Matters discussed at SAC meeting May 3-5

  1. SAC approves the CFHT proposal to delay replacement of the primary mirror seals until summer 2000, considering the risk of interim failure against the impact on other efforts this year.
  2. Feasibility study of modification to upper end configuration to allow rapid switching between PF and Cassegrain Focus.

Reccomendation #2:

The SAC remains interested in the possibility of modifying CFHT to allow rapid switching from Prime to Cassegrain Focus by means of a swing-in apparatus to have the f/8 secondary mirror and support into the beam from one side. The SAC thanks Walter Grundman for his Interim Report dated April 26, 1999 and requests further study of this issue. The SAC feels that it is not acceptable to adversely impact the design of the new top end for Megaprime. As an example, a light-weight secondary mirror might be considered. The SAC also requests that less expensive options be explored, as the estimated cost of nearly $1M seems disproportionate.

  1. Queue scheduling

SAC accepted the CFHT decision not to offer queue scheduling this semester, as previously promised and planned, as the problems of cost and staffing (two-person rule for the summit) have not yet been adequately addressed. There was extended discussion on these aspects, as well as the way in which data will be supplied to the observers. The detailed queue plan seems satisfactory but will possibly need some changes as experience is gained.

Reccomendation #3:

The SAC recommends that CFHT pursue its efforts towards implementing queue-scheduled service observations for CFH12K, and also for AOB. The ultimate goal should be to deliver fully calibrated data (including photometric calibration), so as to maximise the value of the archive. The SAC however considers that many of the benefits of queue scheduling can be attained before this ultimate goal is reached, and therefore recommends that this observing mode be made available even before CFHT is able to calibrate the data (using observing programs that include their own calibration exposures). This should probably be started on a voluntary "shared-risk" basis. Given the significant effort required to adapt observing proposals to queue scheduling, the SAC requests that the CFHT offer this mode of observation only after its availability is certain. The SAC also notes that there are still some outstanding questions regarding staffing and funding.


In addition to the pre-meeting recommendation on funding above, SAC continues to look for progress. It was felt that the working group has been inactive but may play a useful technical role once partnerships have been established.

Reccomendation #4:

The SAC expresses again the interest from the CFHT community to have a rapid access to a wide field infrared camera. SAC therefore encourages negotiations with possible partners already engaged in similar projects and in particular with the PPARC in connection with UKIRT.

  1. Future of CFHT

There have been extensive discussions within the Canadian, French and Hawaiian astronomical communities concerning the future of CFHT, including the Next Generation CFHT Committee Report, the Arcachon meeting in France and the Long Range Planning Panel (LRPP) activity in Canada. The last year has seen impressive developments in the attainment of high image quality in 8-m class telescopes.

The SAC strongly affirms that the CFHT will retain its ability to produce first rate science through to the year 2006, using the MegaPrime facility complemented by a wide field near-IR imaging capability (WIRCAM or similar).

The SAC recognizes that the Canadian astronomical community, through the LRPP activity, has identified a serious deficiency in its access to 8-m class telescopes and the high scientific interest in a wide-field 8-m telescope and has proposed a fast-track replacement of the CFHT with such a telescope. The SAC notes that the French community, which does not face a similar deficiency in this area, has identified other priorities for astronomical investment in the near-term, specifically the LSA/MMA (ALMA) and will not be in a position to invest in a "wide-field 8-m" in the near-future.

Reccomendation #5:

The Canadian members of SAC recommend that NRC explore the possibility of securing a fast-track "wide-field 8-m" project on Mauna Kea with other potential partners including the United Kingdom and the United States, possibly with the intention of replacing the UKIRT, the IRTF or the University of Hawaii 2.2m telescope. Since France might wish to be a minority partner in such a project, the SAC recommends that the CFHT play a role in exploring such partnerships. Alternative developments for the CFHT and its site post-2006 should also be explored.

  1. Instrument plan

SAC reviewed invited written submissions on future instrument developments for Gecko, Espadons, FILAO, and GRIF, particularly as they require CFHT funding and staff support. These submissions are in the appendix to this report.

Reccomendation #6:

The SAC endorses CFHT's instrument priorities and recognizes the development effort, that the CFHT is contributing to CFHT12k, Megaprime and the CFHTIR projects, has implications for support of other
instrumentation. Specifically, the SAC agrees that Espadons is a lower priority than Megaprime and CFHTIR, and therefore CFHT can only contribute manpower when it is available and cannot necessarily adhere to the schedule set out by Espadons. Similarly, CFHT contribution to the development of GRIF and FILAO must wait on higher priority projects. The SAC notes that the present level of usage of Gecko does not suggest that CFHT will be able to schedule and support both Gecko and Espadons. The SAC will canvas the high resolution spectroscopy community and will decide at the next meeting which one instrument should be supported.

  1. Megaprime implementation

The SAC was informed that the f/35 top-end ring is filled with lead and is hence unsuitable for use with Megaprime. Fabrication of a new top-end ring for Megaprime would incur additional cost and result in delay for Megaprime, so it is planned that the present prime focus top-end ring will be used for Megaprime. The SAC was presented with a schedule in which first-light for Megaprime in April/May 2001. In this schedule, the present prime focus environment would be unavailable from February 2001, and Megaprime would likely become available for science after several months of testing, perhaps in July 2001.

The SAC was also informed that CFHT has taken on additional development tasks for Megaprime. These include opto-mechanical design of the wide-field corrector, electronic hardware and software control of the guider, and hardware for and software control of the focus unit. This will diminish flexibility in the schedule for Megaprime and the availability of support for lower priority initiatives.

Reccomendation #7:

The SAC strongly feels that loss of a wide-field imaging capability for a period of 6 months is not acceptable and re-affirms its recommendations that loss of wide-field imaging capability during the transition to Megaprime should not be more than two consecutive months. The SAC requests that a detailed plan for the transition to Megaprime be prepared. This plan should identify the trade-offs between maintaining use of wide-field imaging capability, and rapid commissioning of Megaprime. For example, the commissioning of Megaprime could be separated into two phases - commissioning of the new prime focus environment first, and subsequent commissioning of the CCD camera. This would permit use of CFH12K with the new prime focus environment in the interim period.

  1. Joint TAC

The SAC noted that the BOD has not approved the proposed joint TAC, and has no further proposal at this time. SAC continues to support joint programs between the CFHT communities, and the present national TAC efforts to facilitate them.

  1. Megacam and survey science.

The SAC discussed the Megacam survey time agreement reached by Hutchings, Vigroux, and Couturier, and accepted it as consistent with its previous recommendations.

SAC noted the letter from David Crampton. It is felt that the Megacam survey program addresses the imaging issue as fast as feasible, but might include a CFHT 12K survey. SAC encourages AOB queue scheduling as a future option to maximise returns from the instrument.

Reccomendation #8:

SAC approves the draft Megacam survey time agreement from the meeting of Hutchings, Vigroux, and Couturier, and will provide CFHT with a suggested call for proposals and working group members, as noted therein. SAC will include in the working group tasks, the need to protect some galactic pole observing time for non-survey programs.

SAC will work with CFHT in selecting working group members, and starting their work, as soon as possible, during summer 1999.

The following was drafted by SAC and CFHT and issued to the CFH communities in June 1999.

CFHT imaging surveys

A call for ideas and working group candidates

The CFHT currently offers wide field imaging with the CFH12K camera, and will commission the Megaprime camera in 2 years. Megacam will have a field over one degree with tip-tilt guiding, automatic focus, and throughput below 4000A. The SAC, CFHT, and Megaprime project have agreed that Megacam will be used for imaging surveys which will be scheduled for a nominal 6 weeks of time per year. Surveys may extend over more than one year but will be selected or reviewed annually by an international review committee. The survey data will be available to all astronomers from participating CFH communities.

The CFH agencies will be asked to approve that this time be allocated from their shares of CFHT time. Non-participating agencies will not have access to survey data. It is also possible that the minimum survey program time could be accomplished by using more time for fewer years. It is desired that this program should be completed on the CFHT without interruption or further major alterations to the telescope. It is currently hoped that Megacam will begin full scale science operations in 2001 semester II.

Processed data will be deposited in a database accessible to the participating agencies as they are completed. Individual survey participants will be involved in processing as needed. Access to data outsidethe participating agencies will await the usual 1 year delay before release, and only raw and calibration data will be publically archived.

The CFHT, with advice from SAC, has agreed to sponsor a working group to to begin planning of an initial suite of programs that account for a nominal 2/3 of the proposed Megacam survey program time. The group should define the filters and observing strategies for a core suite of survey programs. These will take into account survey programs planned or under way elsewhere, and also consider image quality, data processing, and sky areas. The discussions should consider observing date windows, the advantages of queue or shared night scheduling, and the optimum way to complete programs over 5 years or less. Techniques for observing and making use of transient targets such as KB objects or SN should also be planned.

The working group will be appointed by CFHT, with advice from SAC, CEA and Terapix, to represent a balance of interests, expertise, and community. The members of the group should expect to participate in the surveys as they occur, after peer-review.

In order to set up the group, and also to initiate survey planning, this notice calls for survey suggestions, as well as for volunteers to serve on the group.


The CFHT SAC invites brief proposals of ideas for surveys from all CFH communities. These may be from individuals or groups. Responders should submit, to the CFHT director, by July 31 1999:

  1. a description in 2 pages or less of the survey idea and database required

and, optionally,

  1. statement of interest in serving on the working group, plus brief resume.

The group should begin work during summer/fall 1999. Meetings and activites will be funded by CFHT.

  1. Archive

SAC is in agreement with the memo from CADC, and encourages CFHT to incorporate weather information and data quality in the header. SAC would like to see CADC carry out the archive tasks and development as outlined in their memo, and would like to be informed of details as they emerge.

  1. Phase One Observing Proposal Submission (POOPSY).

SAC heard and reported favourable reaction to the new proposal submission system. The appendix contains some detailed coments on it. Problems of transatlantic transmission speed and some improvements in the proposal editing are to be addressed for future semesters. SAC thanks those who worked to develop and implement the system.

This was the last SAC meeting held during the directorship of P. Couturier. SAC would like to express appreciation on behalf of all CFHT users for the leadership and dedication he has brought to the job, and for the impartial way he has worked to maximise the scientific output of the CFHT. During years of increasing fiscal difficulty, under his directorship, the CFHT has retained and increased its reputation for performance, powerful new instrumentation, and scientific achievement second to none. We wish him success in his new post, in which we look forward to continued fruitful collaboration with him.

The next SAC meeting is scheduled for Oct 28, 29, 30 in Hawaii, with summit visit on Oct 27.

J.B.Hutchings (chair) for SAC