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

Attendees: Pat Osmer, Bruce Atwood, Darren DePoy, Tom O'Brien, Mark Derwent, Paul Byard, Jerry Mason, Dan Pappalardo, Ed Teiga, Andy Krygier, & Rick Pogge

Welcome to Andy Krygier, a junior engineering major at OSU who is starting work with us on MODS!

Darren reports that the MODS1 work plan is now done and being reviewed. Individuals should expect to be contacted by Carrie or Darren to provide additional details, and by next meeting we'll be ready to discuss the plan and start handing out report forms for progress tracking and assign tasks.

An issue for the work plan is for everyone to examine their responsibilities for any potential long lead-time purchased items (like gratings) and flag them so we can plan our spending. We don't want to get caught short. Long lead items should be passed along to Carrie to get them into the work plan schedule.

There has been a major setback in progress on the MODS blue corrector lenses.

Paul reports that he has been told by Steve Miller of SOML that during work on the reworked null lens to give better fringe contrast, ball bearings from the null lens mounting were dropped approximately 1.5-meters onto the concave (spherical) side of the blue camera corrector lens parent. The impacts left a series of 4-5mm diameter, ~2mm deep craters in the surface of the glass. Photos were shown of the damage. We may get one corrector w/o flaws, but we don't have photos with the maps of the actual corrector parts in the parent so it is hard to tell at this point. Steve Miller wants to wait until he has finished generating the asphere before taking corrective action.

We need to explore with Steve options for what to do. One option is to blacken the dings, the other is to polish off a few mm of surface, the latter of which does not sound good. Paul needs to get more data so he can do an analysis of the impact on the optical performance.

Needless to say, we are not happy, and await further developments.

With the TSIP money becoming available soon, we will be placing orders for the second set of low-resolution red and blue gratings for MODS2, and placing orders for the two medium (R=8000) red gratings for both instruments. These are long lead items and need to get into the queue at Richardson soon.

We also have funds to begin design of a custom ruling for an R=8000 blue grating. This will be tricky. Paul is tasked with opening discussions with the folks at Richardson Gratings.