Report of the 66th meeting
of the CFHT SAC

Waimea, Hawaii, 11-13 November 2004

Recommendation # 1 - GriF
Recommendation # 2 - MegaPrime
Recommendation # 3 - MegaPrime / Image Quality
Recommendation # 4 - WIRCam
Recommendation #5, #6, #7 - ESPaDOnS
Recommendation #8 - FlyEyes and Ohana
Recommendation #9, #10, #11 - CFHTLS
Recommendation #12 - WIRCam Large Programs
Recommendation #13 - CFHT Future

The meeting was attended by SAC members D. Bohlender, D. Elbaz, E. Emsellem, C. Ftaclas, G. Mitchell, P. Petitjean (chair), C. Pritchet, N. Saint-Louis (vice-chair) and B. Tully. Korean representative Dr. Moo-Young Chun and Taiwan representative Dr. Sun Kwok were present as observers. C. Veillet, D. Salmon, J.-C. Cuillandre, G. Barrick, W. Rambold, P. Martin, N. Manset, P. Puget and L. Albert participated in presentations and discussions.

1. Technical Activities Report

Derrick Salmon reported on technical activities.

Different maintenance or development activities on the building are reported : building air handling, soil erosion, remote monitoring and control of the cooling system chillers.

The DEC oscillations problem is not entirely solved but the much improved performances due to system re-tuning continues.

A significant performance improvement was made to the archive software responsible for transferring data from the summit to Waimea. Near real-time electronic transfer of raw CFHTLS data to the CADC has been operational for several months. Generally, the CFHTLS observations from one night are online at the CADC before the next night’s observations begin.

Despite an increasingly high standard of support given to the administration of MS Windows computers, computers are not secure. A virus attack made the Galil motor controllers used to operate the Cassegrain and Spectrograph units halted. One half of an engineering night was lost.

GRIF has been sent back to the Observatoire de Paris and is still experiencing friction problems. Bad motor bearings were discovered after several cold tests in early August. The new motors are still under test. Both Meudon and CFHT efforts to repair GRIF are constrained due to limited manpower .

Neither the French nor the Canadian TACs received any request for the instrument.

SAC Recommendation #1

The committee has been informed that the Meudon group is ready to send the instrument GRIF back to CFHT. Given the burden from new instrumentation and in particular WIRCam coming on line next semester, we recommend that GRIF be considered as a low priority and that it should not be made available for observers in 2005.

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The software group has taken ownership of the DIMM and is developing software that will be used to automate its operation. The DIMM is scheduled for reinstallation in the dome in early November.

Site testing: CFHT was asked for help. Currently TMT is focusing all its efforts on the north plateau site known as 13N. However, it is expected that IfA will propose the installation of site characterization equipment including a DIMM on the summit ridge within a year. This would be of great interest for CFHT to combine data taken outside and inside the dome.

2. Instrument and Project Reports

· MegaPrime

The camera continues to work extremely well. The maintenance of such an instrument however represents a major load on the staff given the significant number of failures. The amount of effort is larger than anticipated but collaboration with CEA is good and CFHT learns a lot.

The reliability of the rotating valve/pulse tube assembly is an ongoing concern. The rotating valve assembly was replaced in April and July. A new material for the valve seat may be investigated. The primary engineer at CEA responsible for the rotating valve should visit CFHT before the end of the year.

The cryostat continues to be plagued with vacuum leaks. Leaks have developed between the epoxy-metal interface on the connector feed-through flange. CEA is looking into possible modifications to the flange and assembly process but CFHT may seek outside assistance. Two connector feed-through flanges had shorts and should be replaced. Currently, there are no spare flanges at CFHT and the last is being assembled at CEA.

Some problems with the CCD controller electronics, the shutter, the guide probe and fiber connectors have been investigated.

A team was constituted to identify and correct the cause of the unexpectedly large MegaPrime image quality degradation seen off-axis reported during last SAC meeting. Apart from CFHT staff, Murray Fletcher and John Pazder at HIA and Guy Ratier at ESA were asked for technical advise and assistance, while Chris Pritchet and John Tonry have been active participants on the science side. The origin of the image degradation appears to be within the optics of the wide field corrector.

Several tests have been performed but the problem is still not understood. However, during one of the interventions on the wide field corrector, lens L3 was flipped upside down by chance. During the following run, the image quality was noted to be much better although still out of specifications. Detailed investigation showed that the improvement is real and not related to seeing conditions. Work should continue to understand the problem fully.

Based on this report SAC makes the following recommendations:

SAC Recommendation #2 :

SAC notes that the scientific performances of the camera are quite satisfactory. However, this arises at the cost of a huge operational effort. CFHT has faced some failures of the camera (electronics, cooling system, vacuum system etc..), which resulted in the instrument not being available for several days. To solve these problems SAC recommends that CFHT continue to seek support from CEA.

The observatory should commit to have electronic spares in place by the next SAC meeting and should formulate a preliminary plan for correcting the helium cooling system and flange problems.

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SAC Recommendation #3 :

It has been realized that the image quality improves quite a lot when lens L3 is reversed. SAC considers that the improvement is large enough to warrant placing the lens in that position for science observations as soon as the December queue-run. Investigations should be pursued to reach a genuine understanding of the problem.

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· WIRCam

The WIRCam project has progressed well and final integration in CFHT is planned to start in a few weeks.

Rockwell progresses in the optimization of the arrays manufacturing. CFHT is now in discussion for the acceptance of perhaps two out of three science arrays. Rockwell is confident on the possibility to deliver the four science arrays by the end of the year. The optical barrels are now assembled and aligned. The test dewar is now operational for the first cryogenic test of the optics at UdM. The cryovessel from Grenoble should be delivered at CFHT in December. To meet specifications, CFHT will use SDSU detector controllers that are completely compatible with the system already developed.

A fully operational and calibrated camera with science arrays should be available in June.

Discussions are still ongoing concerning the pre-reduction of the data.

SAC Recommendation #4 :

Given the new schedule provided by CFHT for the completion of WIRCam, SAC recommends that the instrument be made available to the community for semester 2005B. Therefore, WIRCam should then be considered as the first priority of CFHT for the coming semester.

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The Final Acceptance Tests in Toulouse took place from May 24 to June 9. The instrument arrived at CFHT on July 12 and had a successful first light and apart from minor problems, the instrument is working very well.

A very serious issue should be addressed very quickly however. The chip that was expected to be used for ESPaDOnS, EEV1, is not usable anymore for science. There are two clusters of hot pixels that bleed and make a few columns unusable. One solution might be to use a spare MegaCam chip although ESPaDOnS was specifically designed for an EEV1-like chip. Another could be to buy a new chip from EEV.

As agreed in the CFHT-Toulouse MOU, ESPaDOnS was to be delivered with a data reduction software package called Libre-Esprit. This is however not a free-use package and the observer will not be able to bring the software back home. Documentation is extremely minimal and Nadine Manset will write with the help of Donati a Users’ Manual and a Maintenance Manual.

SAC Recommendation #5

SAC is very pleased to see that ESPaDOnS had a successful first light observing run at CFHT and that the demand for the instrument is large.

There are difficulties with the currently available detectors at CFH. The scientific output would be maximized with a new detector, preferably similar to the planned EEV-CCD. SAC urges CFHT to find a satisfactory solution as soon as possible.

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SAC Recommendation #6

SAC is concerned about the proprietary status of the data reduction package. The executables should be made available to observers to (re)reduce their data at home. A manual should also be made available soon.

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SAC Recommendation #7

SAC notes that the spectrograph could be a unique UV instrument if optimised below 4000 A. It would therefore be interesting to investigate what the cost of installing fibers transparent in the UV would be.

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· FlyEyes and Ohana

The cryostat of FlyEyes has been assembled and delivered to CFHT in November (previous expectations were for a delivery in March). Several developments have been made. Progress on this project is made on a time-available basis. No further work on the Pueo-Nui proposal has been undertaken.

Ohana Phase II is under way. The goal is the demonstration of the potential of an 800-meter fibered interferometer with the 3-10 meter apertures existing on Mauna Kea. The first baseline to be used is the CFHT-Gemini baseline planned to be combined for the end of 2005. One night was spent with the Keck interferometer to validate the fibered coherent transport using single mode fibers. It is suggested an engineer from the instrumentation group be assigned to the project.

SAC Recommendation #8

SAC is pleased to hear that the development of FlyEyes is proceeding well and encourages CFHT to continue this project as resources permit.

SAC is content that CFHT continues to support the Ohana project as resources permit.

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SAC is pleased to note that the statistics of the time spent on the survey is much improved. This is mostly a consequence of much better weather conditions as compared to last semester. In addition, the camera is working well and communication between the coordinators of the different surveys and CFHT has improved and is working fine now. Photometric calibration and homogeneity of the data are satisfactory. Elixir achieves flattening at better than one percent and this can probably be improved further in the future. Comparison between MegaCam and SDSS calibrations is very good.

The first release of the data was expected to happen in June. Technical difficulties at Terapix made it impossible to meet the deadline. The first release has been announced on November 23 and includes data on D1 to 4 in the u, g, r, i and z bands. It will be complemented by data on Wide 1, 2 , 3 and Very Wide by early January 2005. The second release is expected to happen in April 2005 and then release should happen every six months till the end of the survey.

Because of the delay, the format of the first release and its announcement was not properly discussed and publicized. The steering group should discuss the content and announcement of the releases. It seems that communication within the steering group could be much improved.

The mid-term review will take place in May 2005 in Paris. SAC expects 5 reports: one on the survey itself, observing time, data reduction, overall quality and efficiency of the survey; one for each parts of the survey: Supernovae, Deep, Very-Wide and Wide. The reports are expected to reach SAC by March 15 and will be sent to 2 external referees to be chosen later. One person within SAC is responsible for following the process (respectively Petitjean, Saint-Louis, Elbaz, Tully and Bohlender).

The review will be held over two days. The first day should be organised as a workshop on the science with the CFHTLS, including five presentations of the five reports. SAC will discuss the reports on the second day and write recommendations on the continuation of the survey.

SAC Recommendations on CFHTLS

SAC Recommendation #9

SAC recognizes that communications between the coordinators and CFHT have improved recently. However, we re-emphasise that a report should be submitted by the steering group to SAC every semester. Furthermore, information in general should circulate more efficiently inside the steering group and between the steering group and SAC. In particular, release dates and information on data products should be widely announced at least one month in advance, after agreement within the steering group. Board policy for CFHTLS data access should be rigorously followed.

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SAC Recommendation #10

SAC also reminds the steering group that the mid-term review of the CFHTLS will take place next spring. This will be held in Paris on May 27-28, 2005. Detailed reports for each of the four survey-components and one for the overall survey (data reduction, archiving, time allocation) must be submitted by March 15, 2005. These detailed reports must include a description of what has been achieved so far, a discussion of the impact of image quality on the expected results and a justification for the completion of the survey. These reports will be reviewed by external referees with evaluations expected by May 1. Each of the five reports will be assigned to a SAC-coordinator who will circulate a summary to SAC no later than one week before the meeting. As a result of this review process, a re-evaluation of the goals and strategy of the survey could take place.

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SAC Recommendation #11

A one-day workshop will be organized by CFHT just before the spring SAC meeting in Paris to promote CFHT Legacy survey science.

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4. Telescope Use and Scheduling

Queue scheduling performs well although this semester was complicated by the inclusion of 13 PI-Programs. The semester is by far the best semester with MegaCam because of good weather conditions.

C. Veillet presented the preliminary 2005A schedule to SAC after the SAC TAC members had reviewed it. PI programs are oversubscribed by a factor of more than two. A strong pressure is noted on ESPaDOnS for the first semester it is proposed to the community.

5. WIRCam Large Programs Workshop

As announced at the last SAC meeting, a workshop on Large Programs with WIRCam was held on November 5-6 2004 at Institut d'Astrophysique de Paris. It has been organised by Jean-Luc Beuzit (WIRCam steering group chairperson), Tim Davidge, René Doyon and Yannick Mellier (CFHTLS steering group chairperson) under supervision of Nicole St-Louis (SAC vice-chairperson) and Patrick Petitjean (SAC chairperson).

About thirty people attended the workshop amongst them seven Canadians. CFHT staff attended via video-conferencing during the whole meeting. 11 LPs were presented: 6 in cosmology, 1 in extragalactic, 2 on the Galaxy, 7 on stellar physics (brown dwarfs , cool objects). The programs presented at the meeting are likely a fair sample , but could also be biased because Canadian were under-represented, and it was vacation time in two regions in France so some French astronomer could not attend.

The number of nights per LP requested ranges between 15 to 360 with an average of 20-60. No one presented a LP that uses only WIRCam to get a breakthrough out of it. All are multi-wavelength science where NIR is definitely needed in order to achieve the science goal.

Cosmology programs clearly focus on CFHTLS-deep and CFHTLS-wide using broad band J, H, K or K' filters. One program needs Y band, one needs a Ly-alpha NB filter. Other programs have obviously more diverse targets: the bulge of the Galaxy, star-forming regions of the Galaxy, open clusters, nearby galaxies, groups and clusters of galaxies. They also have broader request in terms of filters. In particular there is a strong need for NB filters: CO, Br-gamma, CH4, FeII.

After the presentations, two groups formed in order to coordinate and prepare joined proposals focussed on the Deep (likely D1 and D2), and on the Wide (likely W3 and extension of W1 on non- UKIDSS area).

All attendants were informed about the general rules envisioned by SAC and Board. It is proposed that a LP that is rejected by a joint TAC should still be kept in competition as a LP-PI program by national TACs. No one sees a need to a clear upper limit on the number of nights a LP may request, but it is requested that CFHT provides soon the number of expected nights per agency foreseen for WIRCam.

It is widely accepted that, as for CFHTLS, the LP data should be made available to all communities that provide observing time to a LP.

TERAPIX is ready to provide help and to process any WIRCam data (LP or PI) on request, without regards on the scientific domain. The multiple-pass pipeline TERAPIX for MegaCam should work for WIRCam without much additional work. Some tests have been made already with ESO/NTT/SOFI data.

TERAPIX will request special funds to the French agency in order to duplicate computing capabilities for WIRCam data.

The discussion during the SAC meeting was at minimum as participants thought that all had been discussed previously. A concern is raised however about the number of nights that will be available for WIRCam in general and for LP in particular. It is believed that, given the small number of nights that can be foreseen, it will be very difficult to accommodate LPs without a political willingness. Not all SAC members share this view and it is reiterated that TACs should be the place where LP are decided.

SAC Recommendation #12:

SAC reiterates the view that Large Programmes (LP) are important to give rise to the best science with WIRCam. However, we recommend that the Call for Proposals for LP should be released after the next SAC meeting and should be for semester 2006A. We suggest that the French and Canadian TACs meet at the same time to allow for common discussions which should occur after initial independent rankings by each committee to identify the potential issues.

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6. CFHT Future

What to do during the five coming years 2005-2010 ?

Christian Veillet presented a plan for these years that has been discussed in house to try to maintain the high level of motivation needed to produce world-class science in the period 2005-2010. R&D developments could be centered on the refurbishment of the AO system, a possible laser guide star system and the Ohana project.

In any case, at the end of 2005, CFHT instrumentation should consist of MegaPrime, WIRCam, ESPaDOnS, Pueo, MOS, and Gecko. SAC will almost certainly have to revisit the issue of decommissioning MOS and Gecko at that time.

Christian Veillet indicated that the long-term future of CFHT is partly linked to the possibility of other partners joining the Corporation. The site itself could be of interest for specific projects. Another solution would be to replace the telescope by another facility dedicated to a single project and hence relatively inexpensive to operate.

SAC is concerned that CFHT may meet with budget difficulties.

In 2004 the Agency annual funding was not sufficient to cover the operating costs of the Corporation when, at the same time, it is asked to maintain a very high standard on a large number of instruments.

SAC Recommendation #13:

The substantial investments made recently to install unique new instrumentation (MegaCam, WIRCam, ESPaDOnS) will produce world-class science at CFHT. There is a continuing need to support efficient operation and to bring these instruments to full functionality. It is also important that CFHT maintain a healthy level of technological development to attract and retain high-quality staff. Consequently, SAC recommends that the observatory budget be set to a level sufficient to support these activities at least for the next five years (2005-2010).

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7. Other items

CFHT12K – Disposition

The status of the 12K camera has remained unchanged over the past semester. CFHT is still looking for somebody interested in purchasing the camera or exchange it against observing time.


An unannounced visit by the Solid and Hazardous Waste occurred in June. The inspectors main intent appeared to be bi-products associated with mirror coating processes.

Staff; Astronomy Group

Loic Albert from University of Montréal has accepted the vacant Canadian Resident Astronomer position. He is in charge of the WIRCam data reduction pipeline and analysis. The UH Resident Astronomer position was advertised earlier this year but has not been filled and has been re-advertised in October. The candidate is expected to contribute to support of Elixir and QSO coordination. Sam Kim from Korea arrived at the end of May 2004 for a 1-year period. He will work on the DIMM and Ohana projects. Chi-hung Yan, from Taiwan, arrived in early September to help with WIRCam data analysis.

Next meeting

The next SAC meeting will be held in Paris on May 30-31, 2005. A one-day workshop “Science with the CFHTLS” will be organized just before (May 27). The mid-term review of the CFHTLS will take place in the day following this workshop (May 28).

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