Report of 61th meeting of SAC

Québec, Canada, May 5-6, 2002

QSO priorities
QSO user reports
Mauna Kea Weather Center
Semester boundaries
GECKO decommissioning
 CFHT Legacy Survey

    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 was present as observer. Greg Fahlman, Christian Veillet, Derrick Salmon and Jean-Charles Cuillandre participated in the discussions as CFHT representatives.

Agenda items

1.    Time allocation and observing issues (Martin, Veillet)

     NOP status report
     Semester boundaries
     Trends in time application (CFGT, CTAC, UH)

2.    Technical activities report (Salmon)

3.    Instrumentation and Project Reports
     Gecko: status of the UV train
     Fly Eyes (Cuillandre)
     OHANA (Fahlman)

4.    WIRCAM
     Report of the Steering group (Beuzit)
     Need for a "WIRCam legacy survey"?
     Links with UKIDSS, the UKIRT Infrared Deep Sky Survey

5.    MegaPrime project update (Veillet)
     First light, instrument characterization and photometric calibration requirements

6.    CFHTLS
     Start of the SG mandate
     Start of the survey.  Planning for the 2002 year
     Registration procedures and policies
     Data proprietary time and definition of data releases

7. Other issues

1.  QSO/NOP observations
  • SAC received a detailed report on the last 2 semesters of operation of queue observing mode. The committee is very pleased with the current operation of QSO. After examination of the completion level attained for each type of proposal (A to C-grade),

  • Recommendation #1

       SAC strongly expresses the statement that the foremost priority of QSO remains the high-level completion of A-grade proposals. 

  • In order to better understand the way QSO mode is operated in various seeing conditions more information is needed about the way the seeing requirements of the proposals correspond to those of the real observations. Therefore, SAC suggests that a summary of the statistics of the seeing distribution requested by queue programs be provided by the QSO team. This distribution should be compared with the seeing distribution realized for all of the QSO data.

  • At the present time, the feedback from the users who received data obtained in service mode is very small and it is difficult to estimate the level of satisfaction from the QSO users. As it is the case for visitor mode, CFHT should solicit user reports on the operation of the QSO/NOP/DADS system.  This might, for example, provide information about the impact of <100% data validation on PI programs.  Results should be presented to SAC in 2002 November.

  • Recommendation #2

        As it is the case for visitor mode, CFHT should solicit user reports on the operation of the QSO/NOP/DADS system. 

    This might, for example, provide information about the impact of <100% data validation on PI programs.  Results should be presented to SAC in 2002 November.

  • In order to improve the efficiency of the QSO mode, and to optimize the selection of the observing programs to be executed during the night, information about Mauna Kea weather forecast is essential. SAC recognizes that this is a global Mauna Kea issue, which should be operated at the level of the Mauna Kea observatories. Weather forecasts with a timescale of on;y a few hours is considered as a requirement  for the best  use of the telescope in QSO mode. Other issues need to be addressed such as acquiring "upward looking" sky information in the form of an all sky 10 micron camera and a seeing monitor.

  • Recommendation #3

        SAC recommends that CFHT should continue to pressure the Mauna Kea Weather Center to improve the timeliness of this service. If there continues to be no action on the part of the Mauna Kea Weather Center, SAC requests an estimate of the resources required to implement CFHT's own all-sky IR camera and seeing monitoring facilities.

  • Semester boundaries: the difficulty in handling efficient QSO observations at the end of the semesters has already been mentioned at the previous SAC meeting and the QSO managers were asked to present possible solutions. This issue was examined from two points of view, corresponding to the completeness level of the best-ranked programs at the end of the semester, and the difficulty to observe targets with RA's close to the boundary limit of each semester. This last issue is seen as the most critical one, and several suggestions were proposed and discussed.

  • Recommendation #4

         SAC's final  recommendation is that if QSO managers see A-ranked programs that will not be completed then CFHT can contact the relevant TAC(s) chair to see if these should be carried over to the first QSO block of the subsequent semester.  It is anticipated that only 1 or 2 programs per agency will be extended in this manner.

    In order to reduce the effect of semester boundaries, the concept of a 1-year schedule was also suggested but needs more attention before any action can be taken. SAC encourages CFHT to explore the impact of such a schedule change on QSO operations and to propose practical solutions.  SAC will discuss these at the next SAC meeting and will ask the agency TAC's to discuss this possibility with their communities.

  • Trends in time application: a significant decrease in the over-subscription factor of CFHT time appeared for semester 2002B, especially on the French side, confirming a trend already suspected the previous semester. This is interpreted partly to the fact that several groups are now waiting for the start of the CFHTLS. In addition, new instrumentation is available on 8-m telescopes (NAOS/CONICA on the VLT, VIMOS coming soon, HOKUPAA and GMOS on Gemini) and several programs are now shifted towards larger telescopes. Because of  difficulties in the installation of some instruments like NIRI on Gemini, some proposals are sent back to CFHT. One can anticipate that a relatively low pressure factor will remain on CFHT bright time until ESPaDOnS is available, while the overall subscription rate is expected to increase again as soon as the CFHTLS starts.

  • 2. Technical activities report

    SAC received detailed comments from D. Salmon about on-going technical activities at CFHT: dome maintenance, F/8 secondary mirror aluminization, on-going investigations on the declination oscillations of the telescope. Recent detectors developments are strongly supported by SAC, especially the MIT/LL CCDs. There is concern about the failure of one quadrant of KIR. SAC encourages the CFHT technical staff to find a rapid solution which will not interfere with the current schedule of observations: possibilities include repair of the device by Rockwell or replacement with an engineering-grade device of sufficient quality.

    A review of the different projects and developments is presented below.
    Recommendation #5

         SAC recommends that no change in project priorities be made for the upcoming months. 

    3. Instrumentation and Project reports


    SAC acknowledges the information on the development plan of the project. As the detectors have been ordered recently after a few months delay, a shift of approximately 3 months in the overall development plan is now foreseen since the detectors are on the critical path of the project. With a detector delivery by the end of 2003, it is now expected that WIRCAM will be on the sky during the summer 2004.
    Pascal Puget has volunteered as WIRCAM Project Manager. SAC applauds the efforts of Derrick Salmon as interim Project Manager in moving this important project forward quickly.
    A detailed presentation of the FlyEyes experiment was presented by J.C. Cuillandre. SAC wants to congratulate CFHT staff on their initiative in pursuing this upgrade path for PUEO.  The experiment should continue, but not at expense of other high priority CFHT projects.  Considering the fact that FlyEyes cannot be on the sky before the end of 2002, SAC requests that CFHT provide a comparison of APDs vs. CCD performance at the 2003 May SAC meeting.
    SAC encourages CFHT to continue to look for potential technical collaborative efforts from the participating member institutes. Preliminary contacts are quite constructive. In addition, Canadian SAC members will poll the Canadian community for interest in scientific side of the project and solicit science cases. Therefore, SAC repeats its request for a final science case document.
    SAC is very pleased with the SkyProbe development.  Recent progress includes replacement of the detector which provides better sensitivity although with some more complexity in the data analysis, due to some structure at the sub-pixel scale. SkyProbe is an extremely valuable facility and is now available at any time and for all instruments thanks to its new location on the telescope. CFHT should continue its efforts to improve the system with a two-color version.
    Elixir and the fringe pattern correction
    The Elixir pipeline has been tested on data obtained with the WFI camera operated at the 2.2m at ESO. This camera is a mosaic of CCDs very similar to the MegaCam ones and with similar sensitivity to fringes in the far-red. Very successful results were provided, both in testing the robustness of Elixir to handle a large variety of data and in demonstrating that the effects of severe fringing can be very significantly attenuated by software. SAC is very pleased by the demonstrated progress made in dealing with these two difficulties as it  provides confidence for the success of MegaCam observations.
    Gecko / UV mirror train
    Considering that the UV train of Gecko is very lightly used and requires a significant amount of setup to be installed on the telescope, the question of decommissioning the coude UV train was examined by SAC. SAC also recognizes that the UV train requires the installation of the "old" prime focus upper end, i.e. the one presently used with CFH12K, which will soon be modified to accept WIRCam.
    Recommendation #6

         SAC recommends that the Gecko+UV train be decommissioned at end of semester 2003B. This should be advertised in the next call for proposals for semester 2003A.

    In addition, CFHT should produce a summary of manpower requirements and detailed needs for the support and maintenance of Gecko+CAFE for 2002 November SAC meeting. The availability of Gecko in the Espadons era should be examined carefully at a future SAC meeting.

    A document on the Ohana project update was sent to SAC. SAC supports CFHT tests of the Ohana injection module in August 2002, and the subsequent attempt to obtain fringes late in 2002B. CFHT should report the results to SAC at subsequent SAC meetings.
    A science case is expected for the 2002 November SAC meeting. Additional documentation on operational scenarios and data reduction would help assist SAC evaluate the impact of Ohana on the operation of CFHT.

    4. WIRCam and Infrared surveys

    No report from the WIRCam Steering Group was received at that meeting.  SAC discussed the implications of the UKDISS (UKIRT Infrared Deep Sky Survey) for the CFHTLS and in the context of a survey that may be carried out with WIRCam. SAC requests that the WIRCAM Steering Group discuss interest in a WIRCAM survey with community members.  A call for ideas for WIRCAM observing programs must be circulated as soon as possible. A meeting of the Steering Group is foreseen for September 2002 to examine suggestions from the communities. A WIRCAM survey science program, if supported by the community, must be developed quickly and be delivered to SAC in advance of the November 2002 SAC meeting.

    5. MegaPrime status report.

    The MegaPrime project schedule presented at the SAC meeting foresees first light for MegaPrime by early September. However, SAC requests an update of the status of MegaPrime by August 15 in order to evaluate the possibility of the camera being available in 2003A.
    With the present schedule, commissioning time will be relatively limited in the 2002B semester before the start of the CFHTLS.
    Recommendation #7

         While it is hoped that the CFHTLS can start as presently scheduled at the start of semester 2003A, SAC recommends that sufficient time be provided to CFHT staff in order to guarantee that the camera is fully operational before it is offered to CFHT users. 

    Finally, although it is not its mandate to define it and to interfere with the project team, SAC would like to be informed about the plans for MegaCam commissioning.

    6. The CFHTLS

    Since the last Board meeting several actions have been carried out by SAC. At the request of the Board, a revised version of the "Very Wide component" of the CFHTLS was prepared and submitted by the MSWG (now superseded by the Steering Group). This document, received by SAC and examined by the committee, was also sent to two external referees who sent their reports before the meeting. In accordance with the referees comments and after its own analysis, SAC recognizes that by incorporating follow-up observations and multi-color observations (at the detriment of the total area surveyed) the legacy value of the survey is increased very significantly.
    Recommendation #8

         SAC strongly recommends that each component of the CFHTLS now be allocated the number of nights requested in the CFHTLS Steering Group report.  This includes 94, 162, and 194 nights for the Very Wide, Wide, and Deep Surveys with seeing better than 0.9", and an additional 16 and 8 nights for the Very Wide and Deep Surveys respectively with seeing worse than 0.9".  The total of 450 nights with seeing better than 0.9", is within the limits previously set by the BoD. Final decision on the choice of filters and best observing strategy should be produced soon by the Steering Group. 

    In order to better advertise the CFHTLS and its scientific justification, SAC requests that the CFHTLS Steering Group produce a final merged, and carefully edited, CFHTLS proposal for the CFHTLS Web page once the final survey fields have been defined.

    The next step in the preparation phase of the survey is the registration process, which is the responsibility of CFHT. A preliminary CFHTLS User registration page is already being prepared and was discussed at the meeting. SAC will be available for testing it and to provide feedback if required.

    SAC has proposed a revision in the CFHTLS proprietary time policy for consideration by the CFHT Board.

    8. ngCFHT

    A report about recent ngCFHT activities was given by G. Fahlman. Some interesting initiatives are being pursued both on the Canadian and French sides, mainly on Adaptive Optics issues. SAC encourages CFHT to retain an active role in discussions about ngCFHT projects, and encourages the continuation of all ongoing initiatives.