The requirements document was reviewed.
Baldwin suggested that we prioritize the goals that were listed in the document.

• It was decided to put in explicit language that the A/G unit be upgradable to an AO-bonette-type AO feed, and that a means be provided for automatic correction of focus errors induced by the telescope (zenith angle, temperature, etc. -- anything that can be reliably calculated and stored as lookup tables.)
• Diaz reported that Brazil was happy with a straight-through, 4-mirror Cass. location for polarimetry. Simkin reported that there was no interest at MSU in coronagraphic requirements that would need a 2-mirror-to-focus Cass.  On this basis it was agreed to formally drop the goal of a 2-mirror Cass. focus.  A 4-mirror Cass. would remain as a goal.
• The project will provide jigs to ensure that there will be no need for service personnel to stand on the M1 mirror cover!
• The SAC agreed that calibration issues were related to instruments, but felt that structural aspects of a calibration unit should be included in the telescope, not instrument, budget.

Blanco reported that his inquiries with engineering firms who might bid on the telescope structure had included presnetation of the mass and volume envelopes required for Gemini instruments. The vendors did not regard these numbers as being strong drivers on the structural costs. Blanco has worked on a concept that ``captures" the Gemini instrument in a cage. This allows the instrument moment to be bridged and supported on two bearings. The cage also could be used to mount a bench. Blanco replied that the take on Gemini compatibility by engineering ``management" was that is was a given in the design.

McMahan felt that this engineering response was totally unsatisfactory. He felt that the SAC was starting to debate instrument requirements, and needed absolute assurances from the engineering team that Gemini compatibility was not going to limit telescope performance in other ways. He did not want us to get 3-4 months downstream, having made a series of irrevocable and tightly interlinked science decisions, only to be told by the engineers that they've now had time to take a serious look and ``this is crazy". He asked the engineering team to be very careful in its answer, to avoid credibility loss later.

The concern was raised by Simkin that the mounting cube on the other Nasmyth port would not provide sufficient space for other instruments. Cecil replied that the instrument masses were 2100/3 kg each, 0.8m mounting flange which might be of concern to people with folded optics, and rhomboid space-filling volumes that Blanco agreed to sketch and distribute on the Web for comment. The spectrographs were envisioned to go on the straight-through side of the cubes or cube (if the GIRS clone was selected on the Gemini side). Simkin noted that space limits for spectrographs are particularly troublesome because of fold optics and routes for flexure. The SAC asked Blanco to consider the mass and volumes for two instruments and three at the cube, as well as the cage concept. Blanco noted that 2 instruments meant that all then required 4 mirrors to focus.

McMahan felt that the issue remained not whether you can do it.  The question is,is the added cost limiting telescope performance in other ways. In particular, were we trading glass for dumb weight? Could the money being spent on Gemini compatibility go instead to increasing  telescope aperture? The SAC agreed that it needed a reasoned response from the engineers outlining the likely trades that would be made to accommodate Gemini compatibility.

Diaz asked the project to establish what would be a reasonable mass and volume for an IR spectrograph if the GIRS was split into two less capable units. Would the volumes available on the cube suffice? After some discussion it was agreed that this would be taken up by the SAC sub-committee charged w/ the spectrometers, as well as Elias. This needed to be done soon, to ensure that the cluster concept of 2 or 3 instruments, and the cage concept, were valid. Cecil will make the edits discussed today in the requirements document, then circulate it for final approval over the upcoming weekend. Forms will be emailed for signature and airmailed back.

SAC sub-committee membership and task list
A few names were shifted around on the assignment lists. It was agreed that there needed to be a group looking at the optical imager. Baldwin wanted to add a group to deal with AO upgrades. SAC members will spearhead the efforts but are encouraged to draw on expertise at their institution. It was decided that the SAC members identified by Cecil on each task would decide amongst themselves who would be the leader responsible for ensuring that the report is written in time. Report guidelines would be circulated next week. The goal is for these 2 members, in consultation with others at their institution, to develop additional points beyond those suggested by Cecil. The expanded list should come back to Cecil for review by Oct. 6th.

Draft reports should be circulated by Nov 3rd, for a face-to-face meeting of SAC members on the weekend of Nov. 15/16, with a backup closer to Thanksgiving on 22/23 (plan accordingly!) It was tentatively decided to hold the SAC meeting in Tucson on Nov 15/16 because this was 2 days after the next SOAR Board meeting, also in Tucson. Cecil will try to finalize the meeting dates and location with Elston and Dottori by Monday Sept. 30.

The next telecon will be held at the usual time on Wed. Oct 1.  The agenda will be circulated the day before, to include the final SAC subcommittee membership.