Notes from Commissioning Coordination Meeting 29 October 2002 1. Antenna News The issues with the feedarm have been largely resolved and were described in a seminar given by Kim Constantikes last week. Some of the tasks following on from this investigation are underway. The Quadrant Detector is now in the Metrology Lab undergoing tests and measurements. Tests on methods to make the measurement of resonant frequencies of the structure more straightforward are also underway. Phil reported that a panel review of the azimuth track would be held on Thursday and Friday (31 Oct and 1 Nov) of this week. About 10 experts will be coming in for this review. They will hear presentations from the GBT antenna engineering group and make a visit to the GBT. The problems with premature wear of the track will be described in terms of what is happening, and why it is happening. We will describe the short-term mitigation approach -- inserting teflon and zinc shims and runners under the wear plates -- which appears to be having some success in reducing wheel tilts and further wear. We will state that this can probably serve as a stop-gap approach for a couple of years, but that the best long-term solution is likely to be replacement of the steel portions of the track. The panel will evaluate our analysis and approach and give us both a verbal and written report of their findings and recommendations. 2. GBT Commissioning Review Meeting Phil described the GBT Commissioning Review Meeting that will be held on November 12. This will be an all-day meeting that will go through present GBT capabilities, system integration and commissioning plans in the coming months, software development plans, GBT development projects and their interaction with commissioning, AIPS++/Dish status, etc. The purpose of the meeting is to provide general information, to identify issues and possible solutions, and to ensure that the Observatory as a whole is bringing to bear all its available resources in support of the commissioning program. A number of scientists and engineers from around the Observatory, including Dr. Lo, will be attending. The meeting is open to all interested GB staff. 3. Commissioning and program checkout status Dana has been working on pointing issues over the past week. He confirmed the presence of a sign error between the Tpoint model and the model in the control system. Dana also did a test in which sources were tracked over the splice joints in the azimuth track to see if there was any detectable change in pointing. None was observed, within the ~5" measurement accuracy. There was not time to do a planned determination of box offsets, and this will be done later. Dave Hogg is coming over this week to work on observational tests of the 800 MHz modes of the Spectrometer. The priority of mode checkouts was discussed, and we will stick with the plan to check out 800 MHz bandwidths first, then 200 MHz bandwidths. Toney noted that the level balancing between the IF Rack and Spectrometer was now working, but it is done during the Activate stage and you need to be on source before this is started. The commissioning schedule has not been set for Friday and beyond. Ron will work on this. 4. K-band commissioning plan The plan that Ron issued at the last meeting is presumed to be the working plan. Last week, Ron distributed a memo on requirements for multi-frequency observing. Comments should be in by next Thursday, 7 November and will be discussed at the 8 November meeting: Action 29oct02-1: Comments on memo on multi-frequency observing due on 7 November 2002 (to Ron & Richard). -- Commissioning Staff An LNA in the K-band Rx failed and was sent to the CDL for repair. It has been returned and will be reinstalled. Roger was at the CDL on Tuesday discussion amplifier upgrade options. 5. Software status M&C v3.8 will be released on Wednesday, 30 October. Key features of the release will be Spectrometer updates to improve multibank support, antenna improvements for multibeam, etc., FITS file changes, and some other miscellaneous updates. Spectrometer multi-bank capability is vastly improved, but there are still some crashes happening after 300-400 scans. This will be worked on for the next major release (3.9), which is scheduled for December 11. Nicole circulated a weekly update later in the day. All major projects are still on schedule. There will be a mini-release of M&C on November 7 for IF Manager support. John emphasized the importance of addressing some of the requested upgrades to the antenna servo. Some of these involve handling of moves to stow and snow dump positions, and are needed asap before the snows begin. A discussion on this topic was organized for later in the day. 6. Spectrometer Status Rich has been working with Ray Escoffier on Spigot Card and other thorny Spectrometer issues over the past few days. Rick reported that there were lots of engineering mode checkouts in the past week. About 1/3 showed problems and need further work. The possible LO Blanking problem is being investigated. 7. Baseline investigations Dana reported that not much time was available for baseline work in the past week. There will be a test in the coming days on the X-band Rx in which a shorting plate is placed in the waveguide after the feed, which will serve as an effective cold load. This will eliminate any effects from the sky or telescope optics. 8. AIPS++ Status Joe McMullin reported on AIPS++ status. During the past week, Joe has been named the AIPS++ Project Manager. Joe introduced Steve Myers, who has been named the new Project Scientist for AIPS++. Since most of Joe's time will now go to management duties, there are effectively fewer staff assigned to single dish support and development. The implications and response to this have not be determined yet, but there will necessarily be a large change in process for support in GB. A first step in this process will be to write down the set of requirements for offline data reduction. This should start with GBT staff writing a set of specifications, then AIPS++ writing a matching document. In the short term, efforts will continue to concentrate on functionality, useability, and documentation. Glen and Jim have been working a great deal on documentation in recent days. An effort is underway to make the documentation more like a users guide. A dedicated link now exists so that M&C can link with the glish libraries. This should eliminate some of the problems of the past with installations. A new executable, 'gbdish,' now exists that sources the right version of aips++ in one step. 9. Other Business The next Commissioning Coordination Meeting will be on 8 November at 1 PM, returning to the regular Friday schedule. Summary of Actions: Action 29oct02-1: Comments on memo on multi-frequency observing due on 7 November 2002 (to Ron & Richard). -- Commissioning Staff PRJ // 30 Oct 2002