Participants: Baldwin, Cecil (chair & minutes), Diaz, Dottori, McMahan, Simkin
Conversation lasted 1 hr. The telecon was devoted to a discussion of SAC tasks in preparation for the meeting in mid-Nov.

Web-based discussion

McMahan has now setup a ``hypermail archive" on his PC at UNC. SAC members should copy McMahan in correspondence that they wish to archive. He has distributed instructions. Please be careful of ``replies", otherwise the conversational thread will be lost by the server.

Gemini compatibility

Blanco summarized the scope of what he should be able to say by mid-Nov. on costs and possible performance hits from Gemini compatibility. From the moments of inertia he can estimate the requirements on torques. Replying to a query by Dottori, Blanco said we would also look into the effects on tracking and pointing for the two different masses: 1500 and 2200 kg. Costs will come from the sub-contractors. Two design studies will be funded, and are intended to last about 3 months. Costs would come in the replies by mid-Jan.

From a discussion the day before, Cecil learned from Elias that Gemini was trying to make their optical high-resolution spectrograph competitive w/ HIRES on Keck. This was driving the HROS-team to seek a weight waiver above 2100 kg! We are clearly pursuing a moving target! Cecil reported that Elias was exploring the feasibility of placing a larger InSb detector in the GIRS. At the Gemini workshop in Tucson 10 days ago multi-object work in the IR was discussed a fair bit. As a result of this, Todd Boronson was beginning to organize an effort that would lead to an NSF proposal to fund a 1Kx2K InSb array, maintaining the Alladin pixel pitch of 27 microns. Elias had looked briefly into vignetting etc. in the GIRS design and felt that the extra spectral coverage was not compromised by any optics up to the camera. A new camera would probably be needed. He will estimate the cost in a couple of months. Elias also expected that the question of what IFU upgrade would be possible and how much it was likely to cost, by Dec. Both of these otherwise desirable modifications would increase the cost of the clone above the $1-1.5M mentioned by Wolff previously. Finally, Cecil noted that the next GIRS design review is public and currently scheduled for the two days immediately after our Nov. meeting, in case any SAC member wishes to hang around town.

He was sure the instrument committees would explore these possibilities in detail, and felt that every spectrograph design started from the detector .

Review of SAC tasks

Cecil reviewed the various email deliberations of the last week. It was agreed that at this stage, the instrument requirements should be driven entirely by partner science and not by  predefined instruments. The SAC will therefore sift through the Michigan transcripts and viewgraphs archived at the web site, and the SWG report, to ensure that all partner science can be addressed with an instrument suite characterized by R(lambda), fov(lambda), and pixel-scale(lambda). That is a realistic goal by Nov. Then it can be left to the instrument designers to decide what of this to put into ``imagers" and what into ``spectrographs". Simkin agreed and felt that the next step, also feasible by mid-Nov, was to work out detection limits as functions of these parameters. This would allow the science programs to be quantified. The instrument interface sub-committee should also be expected to report in Nov. As Baldwin noted, we have to ensure that the telescope provides all the necessary ``hooks" for calibration (ditto for AO.)  The SAC agreed to proceed with these tasks.

Baldwin felt that we still needed to get into the huge software interface to Gemini, which was buried somewhere in several inches of Gemini docs. Schumacher at CTIO is looking at what level we should patch into the Gemini protocols. Dottori will replace Diaz on the AO sub-committee. Both will work with Moretto to ensure that Brazil keeps the project briefed on AO. Loh will also be on that sub-committee. Simkin will get in touch with Kibblewhite.

It was decided to consolidate the spectrograph groups and let  instrument designers decide later where the wavelength split should be: either at the thermal IR starting near mid-H or at <1 micron where IR materials began to beat CCD's in DQE. For immediate purposes, it was decided to make the IR spectrograph thermal IR (longward of 1.5 microns) and the optical spectrograph from UV to 1.5, the designers could then push the limits. Baldwin felt that we needed to establish a weighting function for fov, to decide how much more science would be enabled from the larger fov. Cecil felt that the same should be done for scattered light control. Moretto would brief the SAC in Nov. about what software is available to analyze the telescope and instruments for scattered light control.

Baldwin felt that we needed to ensure that the instrument requirements would be reflected in the telescope structure. In other words, were the instrument volumes discussed by Blanco at the last telecon going to suffice? He noted that Cecil had emitted an email where he had dumped a strawman spectrograph into the straight-through space and showed that a 2" collimated beam could easily be accomodated with minimal folds. Baldwin noted that 6" beams were standard on 4m spectrographs. [Cecil replies here that 6" beams are used because no-one goes above 1200 grooves/mm. His ``design" for SOAR assumed holographic gratings w/ 3000-5000 ``grooves"/mm, an example of new-technology which should go into our instruments.] It was agreed that we should allow certain instrumentalists at the various institutions to sketch crude designs into the volumes to see the implications of e.g. optical folds on their designs. They could the report back to us in unprejudiced terms whether or not the volumes were adequate, without getting too specific. Ingerson will check the volume for the spectrograph. Cecil noted that we can easily sample the 15-arcmin field with fibers and still use small optics. Baldwin noted that the imagers were also getting large, especially because the optical imager  might change the f/ratio. Loh will also look at the imager volume since he has an interest in a dual optical/IR camera.

Future Oct. SAC meetings

Cecil will be in Australia for the rest of Oct. so will miss these SAC meetings. He will ask  other members to chair the meeting in his absence. Kitty will continue to initiate the telecon calls, now with the correct number for Elston. The topics for discussion should be 5-min long progress reports from the different sub-committee chairs. Kitty is also handling the details for the Nov. SAC meeting.  Please send your travel details to her. She will make arrangements for accommodation at the Clarion hotel on Alvernon (formerly InnSuites, formerly Aztec) unless you tell her otherwise. Also indicate if you will be staying for the GIRS design review on Mon & Tues. Cecil will get more schedule info on that meeting shortly.