From:   casca-members@physics.queensu.ca
Subject: [Casca-members] summary of CFHT future discussion
Date: September 16, 2009 5:41:14 PM PDT (CA)
To:   casca-members@physics.queensu.ca
Reply-To:   casca-members@physics.queensu.ca

Brief Summary of the CFHT Discussion Meeting
From: Ray Carlberg [corrections and further comments welcomed]

Connected (at some time)

1.       Victoria
2.       HIA
3.       UBC
4.       Waterloo
5.       Toronto
6.       QueenÕs
7.       Montreal
8.       Laval
9.       Carnegie DTM
10.   CFHT HQ (Derrick Salmon and others)
11.   Gemini  (Dennis Crabtree)
12.   Definitely others, but donÕt want to give names without being sure

The first comment is that although this video/telecon was a bit choppy
due to first-time technical complications it looks like it is an
effective means to have a national discussion.  The classical phone
connection was probably the most effective and reliable. Although it
took awhile to get going, by the end, speakers were offering
insightful comments on a wide range of issues.

The minimal conclusion is that there are very strong feelings in
Canada about CFHT.

The context of the meeting is clearly set in a message from Racine,
which has been reordered somewhat below.  ÒThe one unique asset CFHT
partners enjoy is occupying the best-seeing site in the world.  In all
other respects (aperture size, field size, clear sky fraction,
opto-mechanical quality and agility, MIR performance, etc.) some of
CFHTÕs competitors are or will soon be much better equipped, on the
ground or in space. A non-competitive ÒnationalÓ facility is of no
interest.  The median natural delivered image quality (DIQ) over an
arbitrarily large field-of-view at the focus of a perfect telescope at
the CFHT site would be 0.45Ó fwhm at 500 nm and 0.35Ó fwhm at 750 nm.
Any future astronomical use of the CFHT site must take full advantage
of this uniqueness.

High quality, wide field imaging remains a very strong interest in
Canada.  The facts, as far as they are known, are that opportunities
for Canadians are:

á The CFHT IMAKA project is developing a conceptual design with a goal
of 0.3Ó images (i band, roughly) across a 1 degree field.
á Gemini plans to acquire 25 Subaru nights per year (for the entire
partnership), which on an aperture weighted basis with
Hyper-Suprime-Cam will be equivalent to about 250 CFHT Megaprime
nights.
á JWST will of course provide superb images in the red optical, near
infrared and mid-infrared over 2-3 arc-minutes.
á LSST data is planned to be publicly released. Recall that the site
and current plan do not allow for very good images. LSST will map much
of the southern sky.
á JDEM satellite data is planned to be publicÑassuming that the
project goes ahead, although there is a case to be involved to better
understand the data. JDEM will map much of the entire sky.

There is considerable interest in wide-field spectroscopic data at
various resolutions. This is a much more complex situation given the
wide range of science cases. It is notable that many younger
astronomers are very successful at obtaining spectroscopic time at
Keck, VLT and Magellan to undertake spectroscopic work. Particular
science interests cover a wide range.

á 4m R~1000 spectra play an important role for brighter objects and
defining samples for R~40000 work on 8m class telescopes.  An
important issue is to consider what could be done with the existing
telescope with a spectrograph behind the existing one degree field
imager.
á The WFMOS stellar archaeology case greatly excited many people. It
is a natural match to the parallax and proper motions that GAIA will
provide. This is of wide interest internationally, particularly in
Europe.
á The WFMOS large scale structure case probably resonates less
strongly in the observational community but it is a natural match to
JDEM (if approved) and CMB studies.  It is a very broad interest
globally.

 

Finally, there is strong interest in the Canadian community in
maintaining an ongoing program of astronomical instrumentation
development. Instrument development without a telescope that allows or
even guarantees visitor access is very hollow. CFHT has played an
important role in instrument development in the past and in some way
an integrated telescope plan should take this into account.

This discussion suggests a number of next steps.

á The interested scientists should develop the science case and
opportunities for what could be done with multi-object spectroscopy on
the existing 4m CFHT and on a larger replacement telescope.  I will
try to pull together a group to write a report and welcome volunteers!
á Ideally, we should get a better idea of the improvements that
various modifications to the existing CFHT dome would give in the
image quality.  Some of this will be considered in the IMAKA report,
but it is a distinct issue that should be considered on its own.