GMT Instrument Development Gary Da Costa ANU Representative GMT Science Advisory Committee

After initial ideas at the 2006 telescope conceptual design review, in 2009 a call for instrument concept studies was issued. The SAC recommended 6 proposals for funding (from 9 received): GMACS – low res, optical, multi-slit spectrograph(s), natural seeing NIRMOS – low res, near-IR, multi-slit spectrograph, natural seeing G-CLEF – high res, optical spectrograph, natural seeing GMTNIRS – high res, 1-5um spectrograph, AO-fed GMTIFS – 1-2.5um IFU spectrograph, AO-fed TIGER – 3-25um high spatial / high contrast Imager, AO-fed Plus (regarded as a facility, not an instrument) MANIFEST – flexible fibre system proposed by the AAO capable of feeding GMACS / NIRMOS / G-CLEF

Each Design Study provided: Scientific motivation for the instrument Technical feasibility Conceptual/preliminary design Approximate schedule for fabrication Risk Assessment Cost estimate to ~30% and was reviewed by a panel of experts, including representatives from outside the GMT partnership. Process completed by 3 rd quarter of GMT Project budget for 1 st generation of instruments is ~70M US$. The cost estimates for the 6 instrument concepts totaled about twice this figure, so down-select process was required.

Criteria for selection process: Scientific Opportunities enabled by the instruments Link to GMT Science Case and science interests of partners Balance – science, operations, partner involvement Bright vs Dark time, variable seeing, cloud-cover, water vapour AO vs natural seeing: sky coverage for natural & laser guide stars Complementarity with other ELTs (or not) Synergies with other facilities (LSST, ALMA, JWST, SKA) Commissioning constraints Coordination with AO Commissioning Sequencing telescope and instrumentation commissioning Overall Budget constraints Panel (Instrument Development Advisory Panel) formed to advise the GMT Board on the way forward.

IDAP: Chaired by the SAC Chair with the GMT Project Scientist ex-officio member Other 10 members chosen primarily to represent the partner organizations, though 2 members were from outside the partnership. Members covered a wide range of scientific interests and included both experts and non-experts as regards instrumentation Major membership criterion was ability to take a broad view. After a number of telecons and a face-to-face meeting, recommendation made to the GMT Board, which was accepted. GMT is to proceed with development of: G-CLEF – broad science case was particularly noted. GMTIFS 1-arm version of GMACS IDAP also recommended that the MANIFEST concept be further developed to exploit GMT’s large field-of-view (20’) by feeding GMACS1 and G-CLEF. GMTNIRS to be pursued if additional funds can be found.

Next Step – develop full preliminary designs for these instruments. GMT project itself is moving towards a full complete PDR of the telescope and all its associated systems in April next year. Assuming this review is successfully completed then the project will move into the construction phase. At present the partnership has ~35% of the required build funds.