Report of
the 73rd Meeting
of the
Canada-France-Hawaii Telescope
Scientific Advisory Council
Toronto, Canada, 15-16 May 2008
| NOTE: | The
report presented below is the public
version of the SAC report as amended by the CFHT Board of
Directors. The recommendations contained in this public version have been endorsed by the Board. |
| Recommendation
1 |
ESPaDOnS Users' Feedback |
| Recommendation
2 |
ESPaDOnS QSO-PI communication |
| Recommendation
3 |
CFHT-TAC interaction |
| Recommendation
4 |
CFHT-PI communication on
time allocation |
| Recommendation
5 |
C Programs |
| Recommendation
6 |
Phase II no-tolerance policy |
| Recommendation
7 |
CFHTLS 2008B allocation |
| Recommendation
8 |
CFHTLS completion |
| Recommendation
9 |
CFHT-LP interaction on RA |
| Recommendation 10 | LP review |
SAC
members Pierre-Alain Duc (chair), Laura Ferrarese (vice-chair), Chris
Ftaclas,
Brett Gladman, Jean-François Gonzalez, Robert Jedicke and Dae-Sik Moon,
attended
the meeting. Cecile Gry, Henk Hoekstra and Denis Mourard were unable to
attend.
Jeremy Lim from the Academia Sinica Institute of Astronomy and
Astrophysics in
Taiwan and the chairs of the Canadian and French Time allocation
committees,
Gregg Wade and Coralie Neiner, also attended the meeting as invitees. The CFHT director Christian Veillet, Derrick
Salmon, Jean-Charles Cuillandre (for CFHTLS) and Pierre Martin
participated in
presentations and discussions.
1.
Technical activities
report
Derrick
Salmon reported on the technical activities for the period November
2007 - May
2008.
SAC agrees with the following development priorities proposed by CFHT:
1 Operational Priorities
2 New Instrument Development
3 Observatory Automation
4 DIMM
MegaCam
operation
SAC
was informed that no major new failures of MegaCam occurred during the
last
semester; however, minor problems had occurred and were investigated.
The
MegaCam team investigated intermittent communication problems
experienced
between the controller and the detector host computer via the S-LINK.
Due to a
marginal drive signal, clock resets occasionally fail after an exposure
causing
problems for the shutter timing.
SAC is
pleased to see that
the overall operation of MegaCam has been smooth. The MegaCam team
should
address the issues of the S-LINK communication board and shutter timing
board
as soon as possible.
SAC was informed that a major maintenance period for MegaCam would be carried out in June and July with the participation of CEA. Among the planned tasks are the modification of the shutter timing circuit to fix the above-mentioned problem, the replacement of the side rails of the jukebox, the cleaning of the pulse tube, the installation of the new rotating valve delivered from CEA (and successfully tested by CFHT), and possibly the installation of SNDICE.
The SNDICE (SuperNova Direct Illumination Calibration Experiment) project is aimed at improving the photometric accuracy of MegaPrime data using a LED source already installed on the dome and a CLAP (Cooled Large Area Photodiodes) detector to be installed in MegaCam during the major maintenance period. This is a joint effort between the SNDICE team based at the LPNHE laboratory (IN2P3, France, currently involved in the calibration of the SNLS) and the CFHT. Christian Veillet informed SAC that a review of the experiment is planned in the near future to make the final decision on the implementation of SNDICE.
SAC has
not yet been given
the opportunity to evaluate the cost and benefits of SNDICE in detail.
So far,
SAC was not given convincing arguments that future programs with MegaCam would scientifically benefit from
the
implementation of SNDICE. Furthermore, SAC is concerned about the cost
of
SNDICE and wishes to know whether its installation and maintenance may
cause a
risk to the instrument.
SAC
wishes be informed about
the outcome of the SNDICE review before any implementation of SNDICE on
the
MegaCam camera.
WirCam
operation
SAC
was informed that WIRCAM did not have any major problem over the last
year.
After taking care of the negative and positive crosstalk that affected
the deep
stacks, the WIRCAM team successfully suppressed the edge crosstalk.
They were
caused by a grounding problem in the amplifiers of the video channels.
The
first run with the improved control electronics took place mid April.
SAC is
very pleased to see
that the problem of the electronic crosstalk has been solved, and
appreciates
the efforts of the CFHT staff on this matter. CFHT should however still
check
deep stacks to ensure that all the crosstalk has indeed disappeared.
ESPaDOns
operation
SAC
was informed about several minor improvements to the instrument:
reduction of
oscillations, a better red sensitivity for the guider, implementation
of a seeing
estimator and of a new automatic procedure for the focus, setting up of
a new
device and automation procedures to help and secure the instrument
setup.
Finally, CFHT is about to purchase a new triplet lens in the
polarimeter. The
expectation is that it should help to reduce the polarization cross
talk, a
long-standing recommendation of SAC.
SAC
was presented a report to replace the EEV1 detector that suffers from a
few
cosmetics problems and long readout times due to the failure of one
amplifier.
CFHT plans to purchase a new detector (E2V) which would offer a better
quantum
efficiency in the blue and red, better cosmetics (if a grade 1 device
is
ordered), less fringing in the red, no smearing and shorter readout
times using
two amplifiers. According to CFHT, the gain will provide about 30 more
minutes
per night on the sky. The cost of the new detector is $100K while no
additional
cost for the readout electronics is expected.
SAC
recognizes the potential
of replacing the EEV1 detector to improve the efficiency of the
instrument. It
noted however that there is a risk associated with the use of dual
amplification.. SAC was informed that tests are being carried out on
the sister
instrument at Pic du Midi, Narval, and understands that the final
decision to purchase
the detector will depend on the results of these tests. The purchase
order may
occur before the next SAC meeting. SAC also discussed issues of
instrument
ownership and whether it will be necessary to have the consent of the
instrument PI to make major changes. SAC wishes to be informed of the results of the tests as soon as
they
are available.
Observatory
automation
SAC
was informed of the high priority given to this activity that is now
managed as
a formal project with newly allocated technical resources. The
expectation is
to implement routine Waimea based remote observations by 2010.
SAC
sees this as an
important project for the observatory and supports its
continuation, although the planned completion of automation in
2010 may
be somewhat optimistic. The SAC wishes to see the cost estimation
report in the
next semester, together with the estimation of potential risks and a
risk
management plan.
DIMM
SAC
was informed that the DIMM was installed in the dome shutter well but
that a
few major tasks should still be completed before it is fully
operational. The
once unreliable motors of the DIMM telescope were replaced. Inexpensive
CCDs
were successfully tested and purchased. Dedicated software and web
applications
were written.
SAC sees the
construction
of DIMM and monitoring of the seeing as an important long-standing
issue for
CFHT and supports the continuation of the project. In the long term,
the DIMM
information should be implemented in the file headers of the science
exposures.
Mauna
Kea All Sky Mid-IR camera
SAC
was presented a report written by Glenn Morrison (CFHT/IfA) on the plan
for a
Mauna Kea All Sky Mid-IR camera. It will allow a measurement the mid-IR
emission from all clouds, including thin cirrus, and map their
distribution on
the sky even on moonless nights. A commercially available instrument is
being
considered and a demonstration unit will be installed this summer near
the UH
88-inch. If the tests are successful and if the project is accepted by
the
Mauna Kea site monitoring working group, the instrument will be
purchased.
Various Mauna Kea corporations will share the cost. The contribution of
CFHT
should be about $10K.
SAC sees this as a worthwhile project and supports CFHT to lead the project for the Mauna Kea observatories.
2.
AO activities at CFHT and
their future
SAC
was asked by the Board to evaluate the activities on adaptive optics at
CFHT
and to comment on their possible link with the future of AO with this
telescope. Christian Veillet presented to SAC a report summarizing the
past and
on-going efforts on AO at CFHT and giving some reflections for the
future. He
emphasized that the AO system, PUEO, was particularly productive until
2001 and
acted as a reference system for other telescopes. Since then PUEO is no
longer
much used. It has nevertheless still
been scheduled on the telescope each semester to fulfill the need of a
few
scientific programs but mainly to carry out engineering tests (12
nights
between October 2007 and April 2008) and thus maintain AO expertise at
CFHT.
FlyEyes
FlyEyes is an in-house development project to test the use of CCDs instead of the Avalanche Photodiodes (APDs) that are currently used with PUEO. Since last October the wavefront sensor for FlyEyes has been tested three times on the sky. The Strehl performance, limiting magnitude and loop-sampling rate were estimated.
VASAO
The
feasibility of the VASAO (Visible All-Sky Adaptive optics) system was
studied
at CFHT in parallel with the development in France of the ELP-OA
project (polychromatic
laser guide star for the adaptive optics). The concept using a
two-color laser
guide star was found to be unfeasible in visible light in the 2012/13
period
when new instruments are being considered.
Nevertheless,
in November 2007 CFHT carried out a two-color
experiment with natural stars to test
the long-term potential of a polychromatic laser guide star to make
tip-tilt
corrections. In principle, the atmospheric tip-tilt can be inferred
from the
centroid displacements of the light from a single source filtered in
two bands
but no correlation between the tip-tilt and the centroids was measured.
The
experiment might have failed due to poor signal-to-noise and an
inadequate
field size.
The
long-term plan for creating this polychromatic laser guide star is to
use a
mode-less laser (MLL) and the radiative cascade at 589 and 330 nm
following the
excitation of the mesospheric sodium by a single photon. CFHT has
started a
collaboration with the Laboratoire de Spectroscopie Physique (LSP,
France) to
carry out an experiment with an MML purchased on CNRS and CFHT funds
($30k for
the CFHT contribution). The evaluation of the experiment will require
the use
of the other Laser Guide Stars available on the mountain (Subaru, Keck
and
Gemini) and the use of a lidar telescope.
A
key ingredient for the success of the VASAO/ELP-OA concept is the
sensing of
the vibrations of the telescope that induce an extra component in the
tip-tilt
correction that cannot be monitored with the laser guide star alone..
The installation
of a seismometer on the telescope is thus required. Vibration
measurements of
the declination axis with a seismometer mounted on the central pier of
the CFHT
were reported at the 72nd meeting of the SAC.
Future
CFHT instruments
In
his report, Christian Veillet noted that two of the future instruments
proposed
for feasibility studies, `IMAKA and FIRST, could benefit from the
Adaptive
Optics developments at CFHT. The one deg imager `IMAKA does not
initially plan
to use laser guide stars (LGS) but instead a constellation of at least
five
natural stars associated with AO systems. In the longer term the use of
LGS could be considered as an option.
The
high-resolution and high dynamic range imager FIRST would be even more
efficient if coupled with an IR-optimized AO bonnet such as PUEO. The gigantic interferometer `OHANA will
eventually require an AO-correction at each telescope.
[Note added]
SAC opened a discussion on the future of AO at CFHT and on the AO-related developments currently under way at the observatory. This discussion will continue at the next SAC meeting together with the review of new instrumentation proposals for 2013 and beyond.
3.
Telescope use and
scheduling
Queue
ESPaDOnS
SAC
heard the CFHT report on the new Queue mode for ESPaDOnS and received
feedback
from a few PIs. Despite some initial problems with the control
software, data
access to PIs and unfriendly weather, the QSO went well (technically)
during
the first run. The implementation of the QSO required the development
of a new
pipeline called Upena that uses several routines from the data
reduction
software Libre-ESpRIT.
SAC is
grateful to the QSO
team for the efforts made in this achievement. It is however too early to determine the overall efficiency of
the queue
mode for this instrument which, compared to MegaCam and WIRCam, faces
many more
observing constraints, in particular severe time-critical conditions.
SAC
recommends that PIs of
all ESPaDOnS proposals be contacted at the end of semester 2008A to get
their
feedback on the new QSO mode, including the phase 2 process and
interaction
with the QSO team.
The
report given to SAC lists several suggestions to improve the Phase 2
Tool (such
as better finding charts or more flexibility to enter the time
constraints),
run planning and automatic data reduction.
SAC
noted that the success
of the QSO mode of ESPaDOnS would largely rely on the PIs being able to
monitor
the observations and thus be informed about them. Indeed, for
monitoring
programs, an incorrect instrument setting might imply the loss of a
whole run
even if the problem is identified early.
SAC
recommends that CFHT
alert the PI when their program is started and provide access to all
required
information to monitor data quality. When properly justified (e.g. by
the need
for coordination with observations at another telescope) the PI should
be
informed in advance when his/her observations are likely to be
scheduled.
MegaCam/WIRCam
QSO report
Pierre
Martin presented to SAC the usual QSO report for WIRCam and MegaCam.
During the
fall 2007B run the weather was worse than usual. More than 35% of the
MegaCam
time was lost due to bad weather and an additional 5% was lost due to
technical
problems. As a result, the completion level for B programs was only
60%. The
improved focus model contributed to a global high validation rate. The
fraction
of WIRCam time lost due to bad weather was about 30%. Almost no time
was lost
due to technical problems.
As
usual, the balance between the agencies has been strictly respected.
The Deep
part of the CFHTLS, which was affected by the break of the i' filter, did not get its full share of time.
SAC
notes that the QSO
statistics provided by the CFHT to the SAC could be of interest to the
chairs
of the national TACs. Even more useful would be the success rate of all
proposals for which an allocation of time had been recommended. Such
information is already available on the QSO web site but is not easy to
retrieve. Compiling the data in a compact table would be more practical.
SAC
recommends that CFHT
inform the chairs of the national TACs about the status of all A, B and
C
programs after the end of each semester including an indication of
their level
of completeness.
Status
of C programs in QSO mode
Some
misunderstanding has arisen in the community about the status of the
so-called
C ranked proposals, i.e. proposals ranked below the cut-off line that
may still
be considered for a phase 2 proposal. SAC received a letter from a PI asking for clarification. The
director
of science briefly explained to the SAC that C-ranked proposals are
considered
as "bonus" proposals. Depending on their probability of being
executed some of them are allowed by CFHT to pass through a phase-2
step and
others not. Contrary to common belief the ranking of the proposal below
the
cutoff line is not the main driver for the decision.
SAC
discussed new procedures
to properly and rapidly inform PIs about the status of the proposal
given the
additional fact that the cutoff line between "accepted" proposals
(ranked A and B) and below (ranked C) is usually not known at the time
the
national TACs meet.
SAC
recommends that after
their meeting the TACs only provide the PIs the relative ranking of
their
proposal and the referees' comments. If
however the TACs decide for any reason not to allocate any time to a
proposal,
the PI may be informed immediately. CFHT
will then be responsible for informing all PIs in due time about the
final status
of their proposal: A, B (accepted), C (only accepted as a backup and
going
through a phase-2) or rejected (i.e. not allowed a phase-2).
SAC
heard from Pierre Martin that the success rate of the C-ranked
proposals that
went through a phase 2 had been quite high during the last semesters.
It is
actually sometimes as high as for the B-ranked proposals even though
the number
of C-hours is much less.
SAC
understands the need for
having backup C programs in the Queue mode context. However, it felt
that their
impact had not yet been fully addressed. Their importance has increased
with
CFHT only operating in service mode. The level of the cutoff line
(counted in
nights) between the B and C ranked proposals is sensitive to the
arbitrary
conversion factor between hours and nights. The conservative decision
of CFHT
to reduce the conversion factor to 5.5 hours per night for MegaCam and
7.5
hours per night for ESPaDOnS will artificially increase the number of
potential
C-programs in the coming semesters. Furthermore, the regulation of the
balance
of time between the agencies is made on a per instrument basis. With
that rule,
C-ranked proposals from a given agency requiring an instrument for
which no
time was granted by the same agency in the A+B categories cannot be executed irrespective of their ranking or
their ability to fill RA holes! Adding more flexibility in the process
will
help ensure that the best possible science is carried out and that the
time
allocation for C-ranked proposals is less random.
SAC
recommends CFHT to
consider various solutions to control the balance of time between
agencies that
would address the issue with the C-ranked proposals.
Suggestions
will be discussed during the next SAC meeting in November.
Phase
II templates and quality control
SAC
discussed ways to improve the quality control of the data obtained in
QSO model
based on the experience acquired with the CFHTLS.
In
his CFHTLS SG report, Jean-Charles Cuillandre explained the reason why
some
CFHTLS images validated by CFHT had been rejected by Terapix. To improve throughput efficiency CFHT
applies a tolerance to the constraints on the data quality (e.g. on the
seeing)
off which the Terapix team was not
aware.
Although
this rule is
explicitly mentioned in the phase-2 document, the SAC is concerned that
some
PIs might not be aware of the policy when filling their phase-2
proposals.
Since some scientific programs cannot accept any tolerance, SAC
recommends that
the Phase-2 template be modified as follows:
SAC
recommends that the
Phase II template be modified with the addition of check boxes next to
the
image quality, sky brightness and cloud coverage that offer the option
to
refuse any tolerance limits.
The
box would be labeled by the heading "please click if you do not accept
a
15% tolerance in these parameters. Note that selecting the field
decreases the
chances of the data being acquired." A link to the relevant web page could be provided.
3.
Current and future Large
Programs
CFHTS
progress and time allocation
On
behalf of the CFHTLS Steering Group (SG) Jean-Charles Cuillandre gave
the SAC a
detailed presentation including a progress report and justification for
future
time allocation.
Following
SAC recommendations, the 2008A CFHTLS observations were carried out
with
priority over PI programs. During the first three 2008A MegaPrime runs,
CFHTLS
observations comprised approximately 50% of all validated MegaPrime
hours
(although the fraction was significantly higher in the first run which
was
badly impacted by bad weather). This is typical of previous semesters,
i.e. PI
programs were not severely affected by the decision to grant priority
to the
CFHTLS.
There
are four main issues for which the steering group requests additional
time in
2008B and 2009A: 1) completion of the Wide Survey (92.2 hours requested
for
2008B); 2) patching of the Wide field (essentially re-observing fields
validated by the CFHT QSO but rejected by Terapix,18 hours requested
for
2008B); 3) photometric calibration of the Wide (11.2 hours requested
for
2008B); and 4) photometric calibration of supernovae observed with the
new i'
filter (40 hours requested in 2008B and 10 hours requested in 2009A).
The total
time request for 2008B is 154 hours, and 10 hours for 2009A.
During
its Nov 2007 meeting, SAC recommended allocation of 50 hours for
completion of
the Wide survey and 4 hours for the photometric calibration of the
Wide, all to
be carried out in the 2008B semester. In its May 2007 meeting, SAC
recommended
that these observations be carried out with priority over PI programs.
Furthermore, SAC discussed whether additional time allocation in 2008B
would be
considered following an evaluation of a detailed justification from the
steering group.
SAC
carefully considered
three separate issues in evaluating the additional time request made by
the
CFHTLS steering group: 1) the interplay between CFHTLS, PI and Large
Programs
in 2008B; 2) whether the 100 hours requested in addition to the 54
already
allocated by SAC in 2008B are justified; and 3) the request to extend
the
program to the 2009A semester to complete the i'-calibration of
supernovae
discovered and followed-up during the 2008A semester.
SAC
feels that the
explanation provided by the CFHTLS steering group justifies granting
the
additional 100 hours requested beyond the 54 hours previously
allocated.
However, SAC feels that allowing these 100 hours to take priority would
have
too negative of an effect on the PI and/or Large Programs.
SAC
recommends that an
additional 100 hours be allocated in 2008B for the CFHTLS and scheduled
with
the same priority as the PI and Large programs.
Any
additional CFHTLS
related time request beyond 2008B should be made through regular PI
programs.
This
applies to the 10 hours
requested by the SNLS in 2009A for the photometric calibration of the
Wide and
to any observations that are not completed in 2008B.
Time
allocation and implementation of the Future Large Programs
A
total of twelve proposals for Large Programs (LPs) were submitted.
Following
the ranking proposed by the Large Program Time Allocation
Committee
(LPTAC) and taking into consideration the feedback given by the
national Time Allocation Committees (TACs) and information on the technical feasibility provided by CFHT,
SAC recommended to the Executive Director of CFHT to accept the
following
programs with the full amount of requested time:
The Pan-Andromeda Archaeological Survey (PandAS)
PI: McConnachie – Instrument: MegaPrimeThe Next Generation Virgo Cluster Survey (NGVS)
PI: Ferrarese - Instrument: MegaPrimeMagnetic Protostars and Planets (MaPP)
PI: Donati - Instrument: ESPaDOnSMagnetism in Massive Stars (MiMeS)
PI: Wade - Instrument: ESPaDOnS
For
all four programs, time is shared between the French and Canadian
communities.
Since no PI objected to the time sharing all the raw data from the new
LPs will
be available to the entire French and Canadian communities with no
proprietary
period. Taiwan provided additional time for one of the proposals. The
Hawaiian
TAC decided not to join the Large Program scheme but will consider
participation on a per semester basis alongside regular PI programs.
SAC is
disappointed with the
Hawaiian TAC decision since it contradicts the official wish of the
Hawaiian
agency to take part in the Large Programs. Furthermore, it adds
uncertainty to
the total amount of time allocated to the LPs that include Hawaiian
partners.
Following
deliberations by the CFHT Board, LPs and PI programs are treated as
separate
agencies and must compete for observing time.
Because
of the severe RA
pressure produced by some of the LPs, SAC makes the following
recommendation:
Each
semester, before the
call for proposal for PI programs, the PIs of LPs should provide to the
CFHT
their expected RA distribution in exposure hours and the parameters
requested
for the image quality. This will be included in the call for proposals
to
inform the PIs where there is heavy pressure.
SAC
discussed the procedures to monitor the progress of the LPs. It
proposes the
following steps:
SAC recommends that the following procedure for review of the LPs be implemented: Every semester, approx. two weeks before each national TAC meeting, LP teams shall submit to the chair of the national TACs and to SAC a short outline summarizing the status of data acquisition, processing and analysis. During the course of the LPs, with at least one semester's notice, SAC will ask for a detailed report describing the science results obtained up to that point, any problems encountered, and a proposed strategy for the remainder of the survey. As a guideline, the detailed report should be expected at the halfway mark.
3.
Future of CFHT
CFHT's
Golden Age plan and the future of CFHT
Christian
Veillet presented to SAC a quick update on the CFHT's Golden Age plan.
Initially made for the period 2005-2010, it will have to be extended to
2012.
This will be addressed during the next SAC meeting.
SAC
was informed that the staff has decreased naturally (with departures
and
retirements) and the number is already at the level foreseen for 2010.
The
Executive Director informed SAC that the Board supported his efforts in
seeking
new CFHT partners. Up to 30 CFHT nights per year could be sold or
exchanged.
SAC was informed about a plan for an exchange of nights between CFHT
and the
AAT starting in 2009B. Five nights per semester are being considered.
New
instrument feasibility studies
Following
the recommendation of SAC and endorsement of the Board, four teams
received
CFHT funding to finance their instrument feasibility study. The
Executive
Director postponed the deadline for submission of feasibility studies
to
October 1st, 2008. The new deadline has been advertised on the CFHT web
site.
SAC will discuss these studies during its November meeting and possibly
recommend one or several instruments for a phase A study.
SAC
was informed by the Executive Director that CFHT will itself evaluate
the
technical feasibility while SAC should mainly discuss the scientific
interest.
Given
the expertise of
several SAC members on instrumentation, SAC felt that it should also be
associated with the evaluation of the technical feasibility of the
proposed
instruments. Three members of the SAC, Dae Sik Moon, Denis Mourard and
Christ
Ftaclas, were nominated to discuss this matter with the CFHT, external
experts
and the teams proposing the new instruments and will report to the SAC
the
technical aspects of the proposed instruments. Given the short delay
between
the deadline for the submission of the feasibility studies and the SAC
meeting,
SAC asked the Executive Director to inform the communities about the
proposed
instruments well before the deadline. The feedback from the communities
will be
an important element in their evaluation.