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.