The Ohio State University College of Mathematical & Physical Sciences Department of Astronomy

Attendees: Pat Osmer, Bruce Atwood, Paul Byard, Dan Papallardo Tom O'Brien, Mark Derwent, Jen Marshall & Rick Pogge,

Optics

Corning has completed the Fused Silica blanks for the Blue Camera Correctors ahead of schedule. Reports from Corning are that the melt exceeds our refractive index homogeneity specification - interferograms will be forthcoming, along with photos of the blanks. We will need to negotiate with Corning for storage while we wait to finish the optics fabrication bid and so can tell them who to ship it to.

Hextek in Tuscon has finished the Collimator and Camera Primary mirror blanks (8 pieces total). They are awaiting an acceptance review to be held at Hextek after the New Year (probably when DePoy goes out observing at MDM in late January). Photos of the unslumped blanks were available for Rick's presentation at the December SAC meeting, but slumping has since been done and was successful on first examination (the blanks are cooling now).

Revised bid packages and negotiations continue between us and the prospective optics vendors. It is clear we are splitting the contract between two vendors, details are being worked out. We hope to announce the first of the optics contracts after the New Year. In the meantime, all discussions are confidential and not reported here [This writer will be mightily glad to stop having to write that soon - rwp].

CCD Detectors

Bruce and Rick paid a visit to Mike Lesser's Imaging Technology Lab in Tucson after the SAC meeting. In collaboration with Steward, we will be getting up to 8 4Kx4K CCD detectors for MODS from a run currently in progress, plus another 2 devices we are going to buy for other instruments (a 4Kx4K imager for MDM and maybe a second copy for elsewhere). The fabrication of the devices is scheduled to start soon at Zarlink/Mitel.

The full 8Kx4K detector plane of MODS will be met by butting two of the 4Kx4K (3-side buttable) devices together. At present, the gap may be as large as 400-microns (25-27 pixels). We have to think through some issues carefully, as in the current design, an image of the slit with the flat would land right smack in the middle of the tap, and be smaller than the gap. Bad. However, very likely the first-light deployment of MODS will use a single 4Kx4K device, since the full 8K is needed primarily for extended spectral coverage in the high-res mode (for which we don't yet have either a grating design or an estimate of the fabrication and delivery time - maybe 18-24 months from the order).

AO and MODS

Bruce went to Tucson before the SAC meeting to attend a two-day meeting on Adaptive Optics concepts for the LBT. Bruce gave a detailed report, along with some ideas for how MODS might be able to use the AO capabilities of LBT after we finish the baseline instrument. Bruce will (hopefully) write up a more detailed report than his PowerPoint presentation in the future to flesh out these ideas.

The next meeting will be after the Winter Quarter starts, probably mid-January 2002.

R. Pogge, 2001 December 20