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Workshop

University of Sydney/AAO involvement in VLT and E-ELT

November 24, Darlington Centre, University of Sydney


Pre-Workshop Information



Program Information (pdf)


Invitation. This document invites you to participate in a 1-day workshop on hexabundle science on November 24 (Monday), 2008. The meeting will be attended by key personnel from the ESO community (Lyon, Potsdam, Marseille). Hexabundles see first light on SOAR 4m in Chile later this year, and we are now moving quickly to install these on the VLT by 2010. The workshop will also discuss our involvement in ERASMUS for the EELT (first light: 2018). There will be technical sessions over the days November 25-26, 2008 that will address the details of the VLT and E-ELT developments.

The workshop will be devoted to science talks mostly. I would like to encourage interested U Sydney and AAO staff to consider giving a talk on their science areas of interest. Now is the time to put down a marker! This technology has the potential to revolutionize how we carry out and think about optical (later IR) wide-field surveys. You can think of each hexabundle as an “imaging fibre” that will produce superior data to the SAURON survey for huge numbers of objects.

Background. The Astrophotonics Group and the Australian Astrophotonics Partnership (USyd/AAO) have been developing a new photonic device – a hexabundle – that has the dimensions of a conventional multimode fibre but samples an object over a contiguous hexagonal format (up to 397 spatial positions). This is a major development for future wide-field surveys because these devices have low loss, conserve brightness and can be used within conventional robotic fibre positioners; commercial “imaging bundles” do none of these things.

One can now envisage many of these devices (~100) roving over a wide field on the AAT, Subaru, WIYN, Magellan, VLT, Gemini, GMT, TMT or E-ELT. There are numerous scientific applications, not least the build-up of baryons, dark matter, chemistry and angular momentum in galaxies over cosmic time. Some details can be seen in my Dunk Island talk in April 2008 (http://www.aao.gov.au/conf/dunkisland).

SOAR. A demonstration of the technology is now well advanced and will see first light on the SOAR 4m in Chile by the end of the year or possibly early next year. The robotic positioner developed by G.N. Cecil (U. North Carolina) can place four 1×61 bundles over a 5’×11’ field where each bundle has a field of view of 6” sampled 0.67”. We will upgrade to 1×167 (10” field) during 2009. The bundles feed the Goodman optical spectrograph. (1×A indicates 1 input port and A output MMFs; the input port has A cores.)

VLT. Roland Bacon (Lyon/ESO) and Martin Roth (Potsdam/ESO) have now agreed to explore hexabundles on the VLT with a longer term view towards the E-ELT. Our fast track concept is to install ~10 hexabundles on the VLT in the next two years. Each hexabundle will have up to 397 apertures1 (1×397) sampled at 0.4” giving a total field of view of 10” for each. These will be deployed over the full 24’ field with the FLAMES positioner built by the AAO. The fibres will feed down to two MUSE optical spectrographs (Appendix B); the two 4K focal plane detectors will be supplied by Potsdam; the hexabundles will be supplied by the AAP (U Sydney/AAO). The systems integration will be discussed in the days following the workshop.

E-ELT. The longer term development relates to ERASMUS, the first light instrument proposed for the E-ELT 42m. This instrument concept follows on from the MUSE spectrograph under development for the VLT (first light: 2012). MUSE is an optical integral field spectrograph with 90,000 contiguous spatial elements feeding the same number of fibres and 24 optical spectrographs! The MUSE team is happy to see us exploit two of these spectrographs by 2010 ahead of their systems integration.

I note with interest that we could reasonably deploy 225 hexabundles with 1×397 sampling over the 24’ field of the VLT if we had access to the full complement of MUSE spectrographs. Had hexabundles been successfully demonstrated before 2005, the MUSE concept could well have gone a very different route. In any event, ESO is now keeping an open mind about whether to pursue the MUSE or the hexabundle approach for the ERASMUS concept, or to incorporate elements of both.

Needless to say, we are not members of ESO and therefore cannot expect to dominate (nor would we want to) any of these developments. But, as Drs. Bacon and Roth will make clear in November, we can expect to lead key scientific surveys for the fast track instrument. There has already been some discussion within the department about possible key projects and related surveys (e.g. ASKAP, GAMA). We will also be invited to participate in the ERASMUS development with the prospect of attracting major funds for the AAP. This will require a number of PhDs and postdocs for our part, and decent lab facilities.

The AAP has been down this path twice already (FLAMES, DAZLE) with ESO and has every reason to believe that this collaboration will proceed with a minimum of fuss, supported by a common MoU. This is an extraordinary opportunity for astronomers and experimentalists at the AAO and University of Sydney, with outstanding long-term prospects for future honours students, PhDs, postdocs and external funding.

AAT concept? In hindsight, one could envisage modifying 2dF to feed a complement of ~200 or so 1×397 hexabundles (1” cores, 23” field) with long fibre leads down to a full complement of MUSE spectrographs. This would allow us to survey up to 100,000 galaxies at z~0.05 over 5 years. Since the 2dF positioner is an integral part of the wonderful HERMES project, we would need to entertain an alternative approach. Indeed, starbug positioners developed by the AAO could do the same task since the positioning needs only to be accurate to ~half a core size, say 50 microns. If nothing else, it shows that the AAT can still continue to dominate the survey game for years to come.

Program Information (pdf)


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For more information contact Joss Bland-Hawthorn

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