The following four statements reflect the LRPIC view on the Euclid and CFHT initiatives, that have now become linked. Background information is provided below.
- We regard ngCFHT as the top LRP priority for CFHT now, and as an essential part of the future of Canadian astronomy, integrated with other facilities on Mauna Kea.
- New and upgraded instrumentation is potentially useful in keeping the current CFHT doing competitive science, but should not lead to development time or observing commitments that delay or jeopardize ngCFHT.
- We note that using CFHT for a survey in support of Euclid would appear to violate that priority. It would also buy a partnership in Euclid that falls far short of the LRP recommendation
- We view CASTOR as potentially a major DE mission, with considerable other science potential. Furthermore, there are other proposed missions that might offer DE possibilities for Canada, such as WFIRST and WISH. It is important to pursue these possibilities.
Euclid. The top priority for space astronomy in the LRP is significant (priced nominally at $100m) participation in a dark-energy (DE) mission. LRP Rec. # 22 states: “The LRPP recommends that Canadian astronomers participate in a major wide-field Dark Energy satellite mission. Joining Euclid or WFIRST as a significant partner would fulfil this recommendation, provided that we can (i) negotiate a partnership in the leading mission, and (ii) identify a contribution to the satellite instrumentation.”
The ESA Euclid mission is presently the only DE mission approved for launch. Consequently, starting in 2011, with full endorsement from CASCA/CSA’s JCSA, CSA and science advisors Ray Carlberg and John Hutchings entered into discussions with ESA and the Euclid science team, and CSA funded studies of ways to contribute to the mission. Such studies involved proposals for additional instrumentation (which exceeded the payload mass and other limitations), providing hardware items in the approved design, providing and characterizing the NIR detectors, and finally, providing the ground-based optical wavelength imaging survey data and analysis needed for the mission. A combination of the ESA schedule, CSA’s budget limitations, and CSA’s schedule for committing to a partnership, steadily eliminated all of these options. The last initiative, to join PanSTARRS and provide survey data handling and processing for Euclid, involved CSA, NRC, CADC, and Compute Canada working with PanSTARRS and Euclid, failed earlier this year. The last opening for Canadian participation in Euclid lies now in a proposal – led by Ray Carlberg, Jean-Charles Cuillandre and Yannick Mellier – to conduct the Northern part of the imaging survey needed by Euclid with the CFHT, after refitting Megacam with higher efficiency CCDs. The details of this idea have yet to be worked out and agreed by either side. The level of Canadian Euclid participation this agreement would buy, is also not agreed , but is expected to include no more than 10-20 individual scientists. According to a document prepared by Jean-Charles Cuillandre, the upgraded MegaCam could be on the sky as early as 2016. The survey, which would cover 7500 square degrees in g,r,I,z, would then require 7038 hours of integration, or 1117 nights assuming an average of 6.3 hours/night of validated time. This would translate into most of the Canadian share of CFHT observing from 2016 to 2022.
We note that the LRP stated that failing involvement in Euclid or WFIRST, a “Canadian Space Telescope (CST) could be developed as a component of a Dark Energy experiment” (rec. # 22).
CFHT. New or improved instrumentation for CFHT is listed as a medium priority in the LRP. In Dec. 2012, CFHT issued a request for proposals for the development of low-cost capabilities to be deployed on a timescale of 3 years or less, with the understanding that a more ambitious upgrade would be implemented in the longer term. The idea to upgrade the CFHT to a larger telescope is also noted as of interest in the LRP. Since the LRP was published, the development of ngCFHT has been very active, and has resulted in the publication of a science-case document and a technical study document. The basic proposal is to replace CFHT by a 10m telescope with a dedicated multi-object spectroscopic instrument, within the same size building at the site. In March this year, a workshop on ngCFHT was hosted by CFHT in Hawaii, and attended by close to 100 delegates from a number of potential partner countries. The science case was broadened, and international interest is considerable. The current timeline for the project has the new telescope on the sky in 2022, which is timely for many of the spectroscopic surveys that will be needed at that time. For this to happen, it is regarded as important to set up a project office in Hawaii within a year, to move the project forward. It is also important that improvements to the current telescope’s instrumentation do not impede the path towards a timely completion of ngCFHT, which has more impetus and urgency than was evident at the time of the LRP publication.
It is clear that these two LRP initiatives – ngCFHT and Euclid participation through a CFHT/MegaCam survey — are incompatible as they stand. The LRPIC mandate is to keep track of such developments and to assess priorities as things evolve. This is the background for the above LRPIC statements on the subject.
- LRP 2010 (PDF)
- CASTOR Report (PDF, June 2012)
- ngCFHT Project Webpage
- ngCFHT Science Feasibility Study (131 pages, PDF, Dec. 2012)
- ngCFHT Technical Feasibility Study (273 pages, PDF, Dec. 2012)