Report of the 62nd meeting of SAC
Waimea, CFHT headquarters,
November 15-16 2002

The meeting was attended by SAC members Pierre Bastien, Jean-Luc Beuzit, David Bohlender (vice-chair), Laurent Drissen, Eric Emsellem, Eduardo Martin , Marguerite Pierre, Chris Pritchet, Geneviève Soucail (chair) and Brent Tully. Taiwanese representative S.Y. Wang and Korean representative M.W. Chun were present as observers. Greg Fahlman, Christian Veillet, Derrick Salmon and CFHT staff members participated in the discussions.

On November 15, a summit visit was made by P. Bastien, D. Bohlender, M.W. Chun, L. Drissen, E. Emsellem, M. Pierre, G. Soucail, B. Tully, accompanied by G. Fahlman, D. Salmon, and C. Veillet.


  1. Technical activities report
  2. Instrumentation and Project Reports
    1. PUEO NUI: organization of a scientific workshop
    2. OHANA: progress report and science cases
    3. Sky Probe: status of the upgrade and upgrade plans, CFHT DIMM seeing monitor
    4. WIRCam: progress report, report of the Steering Group, WIRCam surveys at CFHT
    5. ESPaDOnS: project status, schedule and installation
    6. MegaPrime: project status and commissioning
  3. Telescope use and scheduling for 2003A. Trends in time application
  4. Evolution of the instrumental suite: MOS/OSIS and Gecko/Cafe
  5. The CFHTLS: report from the Steering Group, DOG activities, data proprietary time
  6. Future of the CFHT
  7. Other items

1. Technical activities report

SAC received a report prepared by D. Salmon about on-going CFHT technical activities. Many changes to the technical staff over the last semester have led to a reorganization of the previous CFHT technical groups into an Instrumental Group. This was described during the oral presentation.

Telescope Declination Oscillations:

A report was given about the continuing difficulties with the declination oscillations of the telescope. These seem to occur more and more frequently, and sometimes include severe jumps in declination. Although a detailed analysis of the mechanical structure of the declination axis has been performed, no satisfactory solution has been found as of yet. Discussions with a servo consultant began some time ago but have been postponed recently because of other higher priority commitments of the technical staff, especially during the commissioning phase of MegaPrime. SAC is concerned about the relatively long-term declination oscillation problem: it can induce significant elongation of the images about 20% of the time, and therefore causes significant losses in data quality, especially for instruments which do not include tip-tilt correction. (The oscillations do not affect AOB observations and should not affect upcoming MegaPrime observations once commissioning of the camera is complete.). Given this significant impact on many observing programs, we urge CFHT to increase their efforts to find a solution to the oscillation problem.

Instruments and detectors:

No important changes in the instrumental suite occurred this semester.

The new MIT-2 CCD has been installed on Gecko/Cafe and is now offered (still on a shared-risk basis) to observers. Users benefit from very low fringing amplitudes in the red when compared to the alternative EEV-1 chip.

A severe failure of one of the central CCD’s of the CFH12k camera occurred recently, but fortunately without severe effects on the scientific data. However a replacement of the chip is expected very soon in order to maintain availability of the camera for the next several months.

MIT CCD’s (1 and 2) are now fully tested and mounted in their own dewars. MIT-1 awaits a dedicated controller and so cannot be offered at the moment. Development is continuing.

The CFHTIR controller has been upgraded to give a much shorter readout time.

Several failures occurred in the GriF mode installed on PUEO. The Fabry-Perot was sent back to the manufacturer for repair and is again on the telescope. An additional unsolved problem is the locking of the mechanical wheel that occurs only within the cold. Help from the development team in Paris-Meudon is encouraged in order to make the GriF mode as efficient on the telescope as originally expected. SAC notes that a large number of nights have been allocated to GriF for 2003A on the French side.

SAC recommendation 1:

Given the impact of declination oscillations on most observers, SAC recommends that the priority for solving this problem be moved to second on the CFHT project priority list. This change is made with the understanding that it will not impact the WIRCam development.

Due to the large number of nights allocated to GriF for 2003A, SAC also encourages CFHT's efforts to solve the GriF problems, preferably in time for the scheduled 2003 March run, but certainly by 2003 May.

The top of the new list of CFHT project priorities recommended by SAC is as follows:

Priority Project
A+ MegaPrime
A Declination oscillations
A GriF

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2. Instruments and projects


SAC was presented with a proposal for a workshop for all parties interested in the PUEO NUI project.The goal of the workshop is to gather together experts in the field of adaptive optics, as well as potential PUEO NUI users in the Canadian, French, and Hawaiian communities, in order to discuss whether or not, given the current orientation of the 4-meter class telescopes and CFHT in particular, such an upgrade of PUEO is warranted. A tentative program of the workshop was also presented.

SAC fully supports the idea of a PUEO NUI workshop. Such a workshop should take place in early 2003 so that a report can be presented at the 2003 May SAC meeting. Members of the SAC will be available to assist with the organization of the meeting.


O. Lai presented a progress report of the OHANA project to SAC. SAC is pleased with the first results for Phase I of the OHANA project obtained at CFHT during the August engineering nights.

SAC supports the current efforts to continue Phase II development of the OHANA project, and also urges the OHANA team to pursue additional investigations of possible operational models for the project. SAC also strongly encourages continued experiments that could put the expected sensitivity limits on a firmer footing.

3. SkyProbe and Seeing monitor

An update of SkyProbe developments was presented by E. Magnier, with emphasis placed on the two most recent improvements: a change in the camera with a new device which does not suffer from the anti-blooming features previously identified, and (as shown during the SAC summit visit) the relocation of SkyProbe on the Caisson central of the telescope. Improvements in the quality of the data and the control of systematic effects are spectacular and SAC congratulates the CFHT personnel who continue to improve the performance of this important facility. The implementation of a second camera equipped with a blue filter is highly desirable, as it should provide a direct estimate of the sky extinction in addition to the sky transparency provided by the current one-camera system.

Thanks to the development of SkyProbe, new contacts were made with a group at the IfA (Hilo) in charge of operating a DIMM seeing monitor on top of Mauna Kea. Combining such a DIMM monitor with a SkyProbe camera may enable the installation of a fully automated seeing monitor within or close to the CFHT dome. SAC recognizes that some developments are still necessary to fully integrate this system, in particular in terms of software development. This will require some effort on the part of the CFHT technical staff.

SAC recommendation:

SAC recommends that the second Skyprobe camera be installed on the telescope as soon as possible. It is also delighted in the progress made towards having a seeing monitor at CFHT. We strongly encourage the installation of such a fully automated DIMM facility inside the CFHT dome. In terms of priority in the project list of CFHT activities, we propose a ranking at the B+ level, i.e. just below EspaDOnS development.

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4. WIRCam

SAC reviewed the progress report of the WIRCam project with the newly appointed Project Manager P. Puget. We are very pleased to see that the project is continuing on schedule. It is recognized that the detector controller development is currently close to the critical path and so it is important that this development be closely followed. According to the present schedule the instrument should be on the sky by May 2004 and could be offered to the communities in semester 2004B. The SAC applauds the efforts of CFHT to maintain this aggressive schedule for WIRCam.

SAC also received an oral report from the Steering Group and continues to encourage more active participation of their members in the final definition of the camera and filter set. In particular the choices in the narrow-band filters are still pending and should be defined very soon.

WIRCam surveys:

J.L. Beuzit reported on the recent “Call for Ideas” for wide field infrared surveys with WIRCam and the individual proposals were examined by SAC. More than 15 suggestions had been received at the time of the meeting.These involved 3 types of proposals or ideas: some « survey-like » proposals mostly related to the near-infrared counterparts of the CFHT Legacy Survey, several propositions of « large » programs requiring a large amount of time for a dedicated scientific topic addressed by a dedicated team, and a few PI-like programs which could easily be carried out through the normal process of time allocation. A brief discussion of the pros and cons of a legacy-type survey versus several large PI-programs was conducted, but at this time not enough information was available to decide between the two options for the use of WIRCam at CFHT over the next several years. Before any decision can be taken, much more consideration must be given to this issue by the SAC and the WIRCam Steering Group. SAC requests as a very first step that the Steering Group prepare a summary of the submitted proposals, and the overall program requirements such as the amount of time and the area coverage for each proposal. This summary will be distributed no later than December 15, 2002 and will be posted on the public WIRCam page on the CFHT web site.

In preparation for subsequent WIRCam survey discussions, SAC requests that the Steering Group meet early in 2003 in order to examine in more detail the scientific cases developed for the “Call for Ideas”, and to propose several alternatives for the best use of WIRCam in the next 5 years.An analysis of the amount of time acceptable for each scientific domain as well as of the data analysis requirements and resources needed to fulfill all of the selected programs should be produced. Such a discussion must also take into account the programs and schedules of other large surveys currently in preparation: UKIDSS at UKIRT, VISTA at ESO, Pan-STARRS at UH, etc. A report from the Steering Group is expected by mid-March and will be sent to SAC as well as to the national TAC’s. The TAC’s will be asked for feedback on the desirability of large programs within the member communities, as well as their opinion on the organization of the observing time allocated on WIRCam. The results of this work will then be reviewed at the SAC meeting in 2003 May and a final recommendation will then be made.

SAC recommendation:

A definitive decision in favor or against large survey(s) with WIRCam can not yet be made. Because of this SAC requires several actions to be taken by the Steering Group over the next few months:

- 15 December 2002: publication of the list of proposals received after the “Call for Ideas”, including an homogenization of the requirements. This list should be posted on the CFHT WIRCam web page and distributed to SAC members.

- Meeting of the Steering Group by February 2003 in order to prepare several alternative proposals for the best use of WIRCAM in the next 5 years in the context of surveys and large programs. The issue of whether surveys should be run in PI-mode, or be organized by the Steering Group and SAC, should also be addressed.

- Preparation of a report from the Steering Group to be sent to SAC and to the national TAC’s by mid-March 2003 for scientific evaluation. Feedback from the TAC’s is expected in time for the 2003 May SAC meeting.

- Synthesis and final recommendation will be made by SAC during 2003 May meeting

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An ESPaDOnS progress report was presented to SAC by N. Manset. The present schedule suggests that the instrument will be tested on the sky by mid-2003 and fully commissioned during the fall of 2003. It should be available to the communities for semester 2004A, a small delay when compared to the previous schedule. However, in order to maintain this schedule it was necessary to delay the design of the thermal enclosure for the spectrograph, with the result that the enclosure is now considered to be an upgrade of the instrument. SAC is concerned with the possible degradation of the stability of the instrument and its scientific performance, at least for some programs.

A discussion was carried out about the choice of a CCD detector for ESPaDOnS: there is a strong request from the builders that an EEV CCD (and in particular, EEV-1) be installed permanently on the spectrograph. It is easy to understand why this permanent set-up is required but questions arose about the limitations of the final instrument performance in the red because of strong fringing effects on the EEV CCD’s. It was also mentioned that some fringing was present with EEV-1 data even in the blue, although at a substantially lower level. The implications of this fringing effect should be presented to SAC and to the communities as it may have some consequences on the way ESPaDOnS will be used.

SAC recommendation:

SAC requests an evaluation of the impact of EEV1 CCD fringing on the performance of the ESPaDOnS spectrograph. Quantitative reasons as to why EEV1 is the "only" suitable detector are also requested before this or any device can be dedicated for use on ESPaDOnS.SAC also requests an evaluation of the scientific impact of a thermal enclosure (or lack thereof) for ESPaDOnS

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6. MegaPrime

C. Veillet presented a short update of the MegaPrime integration phase. Final acceptances of the sub-units have been signed (at the end of May for MegaCam in Saclay, and at the end of July for the GSFU at HIA). A first engineering run was carried out in mid-October, and the next two will occur in early December 2002 and early January 2003. A short presentation of the commissioning plan was presented but is still under development. Although there has been a shift of a few months in the schedule for MegaPrime compared with the schedule presented in May, SAC recognizes the desirability of a careful, detailed integration plan, sub-unit by sub-unit, before final assembly and the first tests on the sky. SAC encourages the CFHT technical staff to make every effort to maintain the present MegaPrime schedule. SAC also asks to be kept informed on progress during the commissioning phase of MegaPrime over the next few months.

7. NOP

P. Martin presented a summary of the QSO operations for semester 2002A. Despite a significant amount of bad weather throughout the semester, a 90% completion rate was achieved for the A-ranked programs. SAC is very impressed by this result, and it again demonstrates the efficiency of queue scheduling in completing the execution of the most highly ranked scientific programs.

Replying to a request from the SAC, statistics on the image quality (IQ) obtained on the images were presented and compared to the requested ones. Once again the results demonstrate the success of queue scheduling: more than 90% of the data have an IQ better than the upper limit requested!

SAC recommendation:

SAC is very impressed by the quantitative success of queue scheduling operations as they are currently being carried out at CFHT. SAC therefore urges the Board to provide additional financial support to continue to ensure the efficient operation of QSO, especially in the MegaPrime (and WIRCam) era.

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3. Telescope use and scheduling for 2003A

SAC TAC members reviewed the schedule of the telescope for 2003A. No great difficulties were encountered with the ranking sent by the national TAC’s. An examination of the distribution and evolution of the number of nights requested per instrument in the French and Canadian communities shows significant differences: there is a strong interest in high-resolution spectroscopy (Gecko) from the Canadian community, while the French community is very interested in high resolution imaging, especially with GriF mounted on the AOB. This tendency is very significant over the last 4 or 5 semesters and apparently reflects different uses of the CFH Telescope by two communities with considerably different access to other astronomical facilities around the world.

4. Evolution of the instrumental suite

An examination of the present instrumental suite and its evolution for the next 4 or 5 years was presented by G. Fahlman and extensively discussed by SAC. An estimate of the technical load on the CFHT staff was taken into account in the discussions.

Concerning the dark time instruments, the following issues were discussed:

CFH12k should not be made available to observers once MegaPrime is fully integrated and commissioned. In any case, once WIRCam is assembled on the PF upper end it will not be possible to mount CFH12k on the telescope (i.e., by mid-2004).

MOS/OSIS:This issue is more critical as this instrument competes directly with MegaPrime, and in particular with the CFHTLS. However, it is recognized that MOS continues to be a competitive instrument, even in this era of large telescopes. For example, MOS has a field of view four times larger than GMOS on Gemini as well as better spectral coverage, so both instruments are roughly equivalent in terms of performance for some types of science. This is not the case when compared to VIMOS on the VLT, but MOS is the only low-resolution spectroscopic facility available to the French community in the Northern hemisphere.From the CFHT point of view the load on the technical staff to maintain MOS/OSIS is not huge, but continuous maintenance of software, documentation, and the Laser machine are required.More subtle is the necessity to maintain CFHT technical knowledge and expertise for this rather complex instrument. However, given the fact that the demand for this instrument has been relatively constant over the last several semesters, at the current time SAC does not believe that this instrument should be de-commissioned in the very near future.

For the bright time instrument, the situation is the following:

OSIS/IR: SAC acknowledges the fact that no proposals have been submitted for OSIS/IR for the last two or three semesters. Because OSIS/IR does not compete well with other near-IR spectrographs on large telescopes, we recommend that OSIS/IR no longer be offered to CFHT users.

Gecko: As requested by SAC at the last meeting, an evaluation of the manpower requirements for maintaining and supporting Gecko was examined. After the de-commissioning of the UV train and the commissioning of the fiber link (CAFÉ), it is recognized that the load on the technical staff is now rather modest and comparable to what is expected for ESPaDOnS. Moreover, due to the continued strong interest in high-resolution spectroscopy from the user community, SAC does not believe that the decommissioning of Gecko should be scheduled before ESPaDOnS is fully tested and operational. Such a decision is therefore postponed until the user communities indicate a strong preference for ESPaDOnS vs. Gecko.

AOB: At present, most users of PUEO come from the French community, thanks in particular to the GriF mode. However it is anticipated that without an upgrade such as the proposed PUEO NUI, adaptive optics at CFHT will become less and less competitive once most of the 8m telescopes are equipped with similar facilities.

CFHTIR: It is anticipated that CFHTIR will be automatically replaced by WIRCam as soon as the latter is available.

Among the new developments anticipated over the next years, a Prime Focus fiber-feed for ESPaDOnS attracted the attention of SAC.If available in QSO mode, such a facility would make optimal use of CFHT observing time when seeing conditions are poor. If such a development is initiated, the desirability of locating such a fiber-feed on the MegaPrime prime focus rather than the WIRCam prime focus appears to be clear. MegaPrime is likely to be mounted on the sky for a larger number of nights than WIRCam, especially during the CFHTLS era, so it seems rather obvious to suggest this focus as a first priority. Bad seeing conditions impact optical imaging observations more than near-IR observations, so this also suggests that a MegaPrime fiber-feed is preferred to a WIRCam feed.

Finally, again assuming its availability in QSO mode, such a feed will also effectively increase the amount of dark time available to MegaPrime users.

SAC recommendation:

MOS/OSIS: SAC does not recommend decommissioning MOS/OSIS at the current time. The case for decommissioning MOS/OSIS should be revisited if either the required technical support becomes burdensome or demand for the instrument decreases significantly.

OSIS/IR: SAC recommends that OSIS-IR no longer be offered to CFHT users.

Gecko: SAC recognizes that Gecko may be decommissioned after ESPaDOnS has been commissioned and shown to be fully operational. We recommend that a decision on decommissioning be made after the performance of, and demand for, ESPaDOnS has been demonstrated.

PF feed for ESPaDOnS: SAC acknowledges the scientific benefits of having a PF feed to ESPaDOnS to help make optimal use of bad seeing conditions in QSO. SAC would prefer to have a PF feed to ESPaDOnS available for use with MegaPrime. However, SAC recommends that CFHT make the final decision on a PF feed on the MegaPrime or WIRCAM upper ends based on the level of effort required.

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C. Veillet reported on recent activities from the Steering Group including development of the CFHTLS Web page, the start of the registration process, and the opening of several mailing lists and the subsequent lively e-mail exchanges. A meeting of the Steering Group took place at the end of August and a detailed presentation of the CFHTLS was given at the meeting on « Structure Evolution and Cosmology » in Santiago in October, with a lot of feedback from meeting participants. C. Veillet announced that due to his new commitment as Interim Executive Director starting in January 2003 , he will resign from the Steering Group.

He proposes Jean-Charles Cuillandre as his replacement. SAC endorses this choice with enthusiasm.

The final choice for selected fields for both the Wide survey and the Deep/SN survey are now close to convergence, after extensive discussions between the Steering Group and the participating communities. This choice will be announced on the CFHTLS Web page as soon as it is finalized.

A Memorandum of Understanding (MOU) between the three institutions (CFHT, CADC, and Terapix) involved in the data processing of the CFHTLS was presented to SAC in its draft form. Comments have already been received from the three institutions. A few more details have to be completed before the agreement is signed. In the meantime, preparation of the Interface Control Document (ICD), which will be attached to the MOU, has progressed well, especially since the formation of the CFHTLS’s Data Operation Group (DOG). Weekly teleconferences have led to a better definition of the content of the meta-data distributed at the same time as the pixel data themselves. SAC is encouraged by the progress in data processing and distribution for the CFHTLS.SAC also urges the participating partners to maintain the view of the CFHTLS data processing and distribution system as a very important collaborative effort rather than as a set of rigid institutional contracts between partners.

Extension of the Proprietary Time of the CFHTLS data:

SAC received a detailed justification of the request for an extension of the proprietary time of raw and pre-processed data of the CFHT Legacy Survey, unanimously endorsed by the CFHTLS Steering Group. SAC agrees that such an extension is justified, both scientifically and technically.SAC therefore endorses the CFHTLS « 3-2-1 scheme » for the public release of both raw and preprocessed survey data. The final decision should be taken at the Agency level.

The UH SAC representatives expressed concern over the fact that this change in the data access policy for a substantial fraction of CFHT data was made after the UH community had decided not to participate in the Legacy Survey.

6. The future of CFHT

The near-term future of CFHT is mainly related to the instrumentation evolution and was treated as a full item during the meeting. One can also start thinking about the extent of service mode operation in the future. Although it is an expensive operational mode, SAC is convinced that it is very valuable scientifically, as demonstrated by the present success of NOP operating the CFH12k. The longer-term future is related to the ng-CFHT activities and other projects starting within the three communities. SAC recognizes that each of the member communities is interested in very large optical telescope initiatives and acknowledges the fact that several projects, which may interest one or another of the communities, are emerging in the international context. SAC is convinced that the success of the CFH collaboration has been such that efforts must be pursued to examine the prospects of a joint project and encourages a continuation of the existing collaborations between France (Observatoire de Marseille and Observatoire de Paris-Meudon) and Canada (HIA).

SAC recommendation:

SAC strongly recommends that the CFH communities pursue technical activities jointly in the framework of CFHT, with the participation of CFHT staff where appropriate.

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7. Other items

Some changes in SAC membership are foreseen for 2003: SAC members M. Pierre and L. Drissen are leaving at the end of 2002. New members will be announced in the new year. G. Soucail retires as SAC chair and will be replaced by D. Bohlender.

A spring meeting is foreseen on May 16-17 2003 in Toulouse (France).
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