Participants: Baldwin, Cecil, Diaz, McMahan, Smith (MSU). Absent: Dottori, Elston, Simkin. The telecon lasted 45 min.
Efforts to prepare for the SPIE conference were distracting the project team this week.
A preliminary report from L&F documents their mount concept. They propose to bear both vertical and horizontal loads on hydrostatic pads. Their design takes a Gemini-class instrument on each side of the telescope. Gemini compatibility is addressed in their document in terms of the effects this mass has on the first 3 structural resonances. 2 Gemini instruments: 11, 15, 18 Hz; 1 Gemini instrument: 12, 16, 20 Hz; no instruments: 13, 16, 23 Hz. They have not adjusted the structure, simply modeled different loads. They note that the OSS+mirror cell can be made more rigid if structural members are allowed to cross through the cell, i.e. the two are not connected by a 3-point kinematic attachment. If a kinematic connection is made to a carbon-fiber cell, then probably more weight in steel will be required to stiffen the structure than is saved w/ the composite.
The CDR is to be June 2 & 3 somewhere on the UA campus (to allow up to 60 attendees); make your reservations accordingly. The Board will select 2 external reps for NOAO, 2 for Brazil, and one each for UNC and MSU. These are the outsiders, but anyone from the Project communities can also attend and are free to submit written questions. 1.5 days will be spent on the design, 0.5 days on the budget. The review is for concepts so don't expect details, i.e. there will be a number of empty space-allocation boxes. On the other hand, once this review is done, the project moves forward rapidly. Concerns therefore need to be registered by the SAC and external reviewers, probably in more detail than will be in the concepts themselves! Sebring asked the Board to fold the review desired by Brazil into this CDR to expedite the process. All review material will be distributed as bound briefing books 2 weeks before the CDR.
Costs will be frozen at the time of the CDR. If the Board moves quickly to approve contracts and cash-flow, then these will be valid enough estimates to simply move forward. Otherwise, more time and money will be spent negotiating contracts.
Gemini would like SOAR to use their building for many activities. They would prefer that the SOAR and Gemini operators both be in the Gemini dome, for safety. Cecil felt that we would need to develop an EPICS driver for pacemakers for that to happen.
A working draft of Part IV Instrument Requirements, has been circulated for comment. One section in particular that awaits the Part I Science Requirements doc (which McMahan hoped to emit early next week, before he leaves for the Kona SPIE conference) is a ranking of the implementation order of the science instruments.
Simkin's efforts on the Science doc are being devoted to the IR imager. McMahan is looking at the other instruments. Baldwin hoped that this draft could be circulated asap, so that others could see the form and help out.
Cecil felt that we can finish the science doc well before the SAC meeting, so that the emphasis in Chile should be to approve what has been discussed rather than endlessly reviewing what is there. Note that a thermal emissivity spec has been added to part IV. Baldwin, Diaz, and Cecil in consulation with IR astronomers felt that 7% emissivity is a reasonable goal for M1-3. This keeps telescope background usefully low in the windows at 2 and 3.5 microns. Cecil had not yet had an opportunity to review with Tom the operational implications of this re. mirror cleaning, etc.
Cecil asked for critiques by email, especially what's missing and the overall order. It was agreed that this document could now be circulated around the partner communities for comments on its completeness but not writing style (which is rough in this draft stage.) Cecil noted that this document still needed links to the more detailed reports that were done on power, etc. a couple of months ago. Baldwin felt that section 5.6 of part IV (Priorities for Instrument Deployment) was the bottom line in our science document. Would this process be complete by the SAC meeting in April? Cecil wanted to get as far along as possible beforehand, but it would be necessary to discuss instrument specifics in Chile to gauge what was possible on our budget.
Cecil emphasized the need for on-instrument tip/tilt sensors to ensure that we meet our image spec. After the concept design phase there will be considerable work within the Project to detail the error budget and understand how we can address instrument flexure. Our tip/tilt sensors differ from the OIWFS on Gemini. We will not do fast-focus. Also, our peripheral sensors are just quad-cells, not wavefront sensors as found on Gemini. We will not use these to monitor active optics.
Larry Daggert has totaled the costs of the optical imager, based on a spare mini-mosaic dewar at NOAO. For $60K (burdened) this dewar could be refurbished and fitted with an ARCON (or Leach) CCD controller. This cost does not buy a filter wheel. 2x4.5K EEV chips are $50K each (in a consortium buy) and we would need 3 of these or 2x6K EEV's to cover 8x8' in Moretto's f/9 reimaging design. The cost of the reduction optics also need to be added in this design. We should have reasonable cost estimates that include these items by early April.
The $1M mentioned by S. Wolff for the GIRS-clone does not include the array, controller, or OIWFS.
One possible approach for the optical spectrograph will come from Australia, but we'll need some way to estimate a multi-slit design. [Elias suggested to Cecil that GMOS would be one way to do this. It is a state-of-the-art (hence not instantly obsolete) f/16 design that would cover roughly 10'-diameter at SOAR. Its slit-cutting laser would also be available in the Gemini-S dome 400 m from SOAR. GMOS will certainly remain full-time on Gemini-S because it is their only optical imager.]
Diaz will host a meeting in 2 weeks for Brazilian astronomers at Sao Paulo. They will review all parts of the SOAR instrument document to verify that it is something with which they are comfortable.
Cecil, Elston, & McMahan will be at the SPIE meeting, so the March 25 telecon will be cancelled. Jack Baldwin has kindly agreed to chair the March 18 telecon since Cecil will be in transit to Hawaii.