Notes from Commissioning Coordination Meeting 4 October 2002 1. Observing Program Checkouts Ron reported that program 2B6 is now ready to be moved from the "active checkout" list to the "to be scheduled" list. Frank reported that of the 5 projects he is checking out, 3 can be scheduled. In other news, Richard reported on the investigations of feedarm motion with the quadrant detector. This will be documented in detail in a separate report. In brief, quadrant detector data are showing motion of the feedarm when it is tipped over that departs from the linear structure model. This departure is in qualitative agreement with the pointing residuals we see as a function of elevation angle. The QD was also used to produce a spectrum of resonant frequencies of the structure. Some unexpected frequencies appear to be present. The antenna and PTCS groups are following up on these measurements by installing some new, high precision accelerometers and by repeating the conventional, optical survey of feed arm motion versus elevation angle. Frank discussed astronomical checkouts of the spectrometer. He showed a table of the status of the dozen or so modes that have been requested so far by programs in the queue. This table needs some more updating, but appears to be a helpful summary of Spectrometer status in the most essential modes. He was asked to place this table on the web once the information is complete: Action 04oct02-1: Place table of requested Spectrometer modes on the gbtstatus web page. Separate single bank and multibank modes in the table. [Frank] 2. Spectrometer hardware status. Rich reported that most of the week had been spent diagnosing and repairing some problems with the Spectrometer that occurred last weekend. There were a couple of different problems, including more paddle board problems. Ray Escoffier and Rich have done some research into possible remedies to the paddle board problems, which appear to be caused by dissimilar metals between the board contacts (gold) and the backplane (tin). Rich has been talking to a vendor who can supply tin connectors for the paddle boards, which should improve the problem (for a few months, anyway). These connectors have been ordered. The large, single-point blips in the auto-correlation functions have showed up in a self-test, which should help to narrow down the source of the problem. The small ACF blips affecting many channels appear to be ground-bounce problems, and delays have been implemented in the Long Term Accumulators to get around this. Ray is coming out again next Wednesday and Thursday to work on the Spigot Card, but may also help with the above problems. 3. K-band Commissioning Plan Ron presented a plan for the next phase of commissioning the K-band (18-26.5 GHz) system. The tasks are identified in Gantt chart form in approximate order in which they should be done. Tasks include the relevant Spectrometer checkouts, baseline work, observing mode checkouts, etc. The commissioning staff is asked to review this task list and get comments to Ron and Richard by noon on Wednesday, 9 October: Action 04oct02-2: Comments on K-band commissioning plan due to RJM and RMP by noon on 9 Oct 2002. [Commissiong Staff] Roger reported on the K-band receiver itself: all the rework has been done, and Mike Stennes has done initial tests and calibrations in the lab. He needs a few more days to refine the thermal calibrations. It is hoped that some time can be blocked out to do test observations with the receiver in the Equipment Room before it is installed on the telescope. This would allow some useful benchmarks of baseline stability. At present, the test time available for this is rather tight, but the schedule will be examined. 4. Software Update Nicole gave an update of software development activities. The new development cycle for M&C v3.8 has begun, and will culminate with a release on 30 October. The primary activity this cycle is developing multibeam and multibank capability. Other activities include continued work on the Configuration Tool, and a variety of other tasks. The software development group has updated the project descriptions on the web page at http://tryllium.gb.nrao.edu This page contains project charters, modification requests (MRs), and the weekly Software Development Division status reports. There had been some discussion earlier in the week by email about further enhancements to the Configuration Tool. Nicole noted that the enhancements being worked on now are things for which there is general agreement. There have been requests for other tools that observers need, such as an on-line status screen. Richard suggested that when the present development cycle concludes at the end of this month, that we consider tasks and priorities again and perhaps address this. The Software Division has been asked to assume responsibility for the data Filler for the AIPS++ Measurement Set. Plans for doing so are under discussion. This will require a rearrangement of priorities and some tasks will be pushed back to accommodate this change. 5. AIPS++ News Joe M. reported that the AIPS++ single dish group is now focusing efforts on useability issues such as speed, robustness, and documentation. New feature development may take a hiatus while this work is being emphasized. The reason for this emphasis is to address the problems that single dish users have been experiencing. Speed profiling will be underway next week (Filler profiling was underway on Friday by Bob). Eric is building a benchmark suite for testing single dish tasks. A new version of the GBT AIPS++ link should be in place by Monday. Jim reported that the new version of IARDS that uses the standard Dish reduction calls is now in place. 6. Baseline investigations Rick reported that X-band baseline studies are now underway. Some preliminary tests with the IF noise source and 40 MHz bandwidth showed stability to the 0.1% level, whereas stability was ~0.5% with the receiver connected. This points toward receiver stability issues. Ron reported that in checkouts for an OH observing program at 1720 MHz, the baselines at 12.5 MHz bandwidth were extremely good. 7. RFI status Rick reported that the RFI group has spent much of its time lately working with the contractors and architects on the shielded rooms in the new Visitor Center. The new 3.6 m RFI-sniffing dish has been installed west of the Lab. Two students from BYU were out to do this, in collaboration with local staff. This dish can be used for azimuthal sweeps with a fairly directed beam. It can also track satellites such as GLONASS, and will be used for the adaptive cancelling research. Rich reported on the feed arm servo work: there are 17 filters remaining out of an original 58 to be installed. This will take about another 3 weeks to complete. 8. Other business The group was reminded of the computer shutdown on Friday afternoon in connection to the scheduled power outage on Saturday. Summary of Actions ------------------ Action 04oct02-1: Place table of requested Spectrometer modes on the gbtstatus web page. Separate single bank and multibank modes in the table. [Frank] Action 04oct02-2: Comments on K-band commissioning plan due to RJM and RMP by noon on 9 Oct 2002. [Commissiong Staff] PRJ // 6 Oct 2002