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

Attendees: Darren DePoy, Jen Marshall, Dan Papallardo, Tom O'Brien, Mark Derwent, Bruce Atwood, Jerry Mason, Paul Byard, & Rick Pogge

Dan reported on his tests of the MicroLYNX controllers. He and Jerry got them running again, after uploading some new firmware. We have one each of their 4-amp and 7-amp units. Dan set them up as before and with the scope can see no sign of the current pulsing problem reported with earlier units. We don't have an example of that earlier problem unit in hand, as it is in Arizona running one of the gate valves for the aluminizing system (where it works just fine and the noise spikes aren't an issue).

One thought from Bruce is to downgrade the firmware and see if the problem recurs, but nobody is quite sure how to do this (or, more precisely, exactly how you go about getting the old firmware).

This is good news, so the next step is to test the limit handling properties of the systems. This is the most critical test they face. Dan will work with Tom and Mark to set this up to repeat their tests with the Applied Motion Products controllers.

Dan has also been working on the interconnect design that would link any controller with the stepper motors, sensors, and outputs. Using data from Amp re: current handling in their CPCs (circular plastic connectors), he found that their 28-pin Series 2 CPC, which we use a lot in other systems, will work just fine. The pin count from Mark's and Tom's mechanism data sheets suggests that 19-pins is currently the maximum we have to deal with, so the 28-pin connector has enough headroom. The idea is to adopt the same common connector for all mechanisms. Dan has not yet selected a cable, but a number exist that meet our specifications. He will also create a list of cable vendors who can make these units for us.

Dan has also started evaluating power requirements. In particular, our CCD head electronics box, rigged like we would use with the 4K CCD, requires 90 Watts per box. He and Jerry are tasked with looking into options for enclosures for the electronics that will connect to the liquid recycling system at LBT to carry away the waste heat. A number of commercial units are available (e.g., as used on GEMINI) that we can explore. The basic goal (after some discussion) is to target "zero waste heat" that isn't captured by the recycling system. This will require working with LBT to get all of the specs for the units. Jerry will be looking into that.

We have taken delivery of the first 4K CCD from Mike Lesser at Steward, and Bruce is going to setup to test it. The actual MODS dewar is not yet designed (it's in the queue), so we will use one of our test dewars (Bruce needs to evaluate the options and make the call). Tom and Bruce are also tasked with getting the MODS dewar design underway. We have a head electronics box for the 4K that Bruce will use for his testing.

No news on the MODS optics from Steve Miller at Steward Mirror Lab. Paul will be trying to contact him again regarding this. In particular, we don't know the current state of the optics fabrication work on the corrector, nor have we received word on when we can expect delivery of the camera mirror.

Paul has been working out the optical alignment protocol for MODS. This has implications for the tolerances with which the camera correctors are cut from the parent, so this needs to be discussed with Steve Miller before the protocol can be finished. It looks like from Paul's analysis (modulo uncertainty about de-center of the corrector from systematic errors in cutting), most of the alignment can be done with the on-axis beam, as the cross-terms for the off-axis points are much weaker. Our plan to use the MODS AGW stage to hold a CCD camera to look backwards through MODS (instead of out towards the sky) at a pinhole mask in the detector plane will give us a very powerful way to align and test MODS using the full optical train of MODS (it also is way easier than building a large test rig to simulate MODS - we'll use MODS itself).

Paul has also been working with one of the prospective vendors for the bypass gratings on various design issues associated with this item. More news on that as things proceed.

Mark reports that we've sent out our biggest anodizing order yet, so we should be getting lots of matte-black metal bits in the lab soon.

We have not received any updates from Indian Creek on the painting of the MODS1 structure, though we have been working with the rigging/moving contractor on the delivery process. We'll need to get Traffic & Parking to restrict parking on 19th Avenue on delivery day, as the truck will need room to get to the loading dock. We've done this before, and T&P has been very helpful.

Mark has begun working on the overall enclosure design for MODS, starting by using AutoCAD to build a model of the instrument with all of its mechanisms in place. The trick is to peel down the immense detail of that model to the essential bits so that it can be handled easily on the computer (we need to know the volumes occupied, and locations of access ports and such, but not every nut and bolt and tiny part). This will give us a nice global model to work with, once he convinces AutoCAD to stop crashing on it.

Assembly and testing of the first AGW stage is proceeding nicely. We don't have a lot of fabrication going on right now, because we've got a lot of stuff built, and things out for finish work (anodizing and such). While much remains to be done, we are now visibly moving from the fabrication to the assembly stages. By our review in March, it should be a lot easier to visualize how all of the pieces of MODS will fit together.

The only issue that has arisen so far is minor: a few people marking their weekly timesheets have not noticed when they've overrun the time remaining items. If you need more time to complete a task, please make a note of how much more time you think you'll need so it can be inserted into the system as part of the weekly analysis. This is not a big problem, but a few things have started to crop up as negative time remaining.

Also, if your work is actually split between MODS1 and MODS2 (e.g., fabrication of parts that are for both), be sure to indicate which is for which so we can properly count that work against the MODS2 schedule.

Some adjustements are going to be needed, Mark will be contacting people with specific questions. In particular, it is clear that the software development parts of the schedule have slipped, in part due to the stall in selecting a motion control system (can't write device-specific software until you have device to write for), and Ray's arrival delays from early January to late February are introducing some slip. Once Ray arrives, he and Rick will go over the entire software plan with Mark (in advance of the March Progress Review) and get that back on track.