GBT Commissioning Meeting 14 March 2003 AGENDA 1. Az Track Status -- Bob A. 2. Spectral Baseline, Front-end, and IF work -- Roger 3. K-band, Q-band, and other commissioning -- Ron 4. Software status -- Nicole 5. AIPS++ report -- Joe M. 6. Spectrometer status -- Rich 7. Project scheduling -- John 8. Observing schedule -- Carl 9. Any other business REPORTS & DISCUSSION 1. Az Track Status o The crack in Plate 44 deteriorated in the past few days -- a parallel crack has now produced a loose sliver. No travel of the wheels across the plate without visual monitoring is allowed. In practice, one passage a day is being allowed, typically at the end of maintenance day, so that the telescope can be set up for observations for the night. o The replacement plate should be ready on Monday or Tuesday of next week. GB Operations is sending a truck to pick it up. o We received four quotations for the mock-up weld of the track modification. Technical review of these proposals is underway. o We will begin weighing the telescope on Monday morning, 3/17. -- RA / PRJ Discussion. Dave Hogg agreed that considerable caution in moving the wheels over Plate 44 was now in order, until it is replaced. 2. Spectral Baseline, Front-end, and IF work Rick gave a presentation on the baseline investigation in CV, which was by all accounts well received. The Ku-Band receiver is ready to be installed on the GBT, and the installation is scheduled for March 20. There are several passband resonances in all channels, but Braatz feels these will not be an issue for the observations scheduled in April. The resonances are thought to arise in the thermal waveguide gap, and we are investigating alternative designs. One such was suggested by Tony Kerr, and Sri will do some EM modeling to assist in the redesign effort. The C-band receiver, with the Cryo3 LNA retrofit completed, is undergoing it's first cooldown. Cold testing and thermal cals remain to be done. The goal is to have it back on the GBT by April 1. The S-band receiver is in the lab for repair of some broken cables in the circular polarizer. This work has been slowed due to other receiver work. Our goal is to have the S-band back on the GBT by April 15. One IF cable type with improved phase stability has been identified and ordered for evaluation. Tests will get underway in the next week. The Q-band receiver was installed and first observation results were encouraging. Poor weather and competition for telescope time has slowed the commissioning. Time has been requested in April for baseline evaluations with this receiver. -- RN Discussion. This agenda item is being expanded to cover front-end and IF items, some of which are related to the spectral baseline problem, and some more general. Phil asked about the nature of modification that Tony Kerr suggested. Roger replied that it was a rectangular waveguide transition with a waffle pattern that isolates the RF. There is still a thermal air gap. 3. K-band, Q-band, and other commissioning We had first light with the Q-band receiver on Monday. The tests revealed a number of minor problems with the hardware and software, almost all of which were resolved the next day. The commissioning goal for the receiver was to determine beam offsets (found to be within the measurement error of the theoretical values) and a rough aperture efficiency (~35% at an elevation of 60 deg during excellent weather). Sidelobes are at worse around -20 dB. There's was some evidence of feed arm motion in some of our data. Focus and pointing looked reasonable. Tsys was about 60 K. Richard will probably discuss his PTCS/FEM tests from Tuesday night. The planned commissioning tests for next week will refine most of these estimates. Glen was been able to check out K-band proposals: 02A63 Claussen/Wootten - Water Masers in Young Stellar Objects 02B03 Sahai/Claussen - Water Masers in Planetary Nebulae 03A19 Swift/Welsh - Ammonia line image of "Pre-Protostellar Clump" all of which can be moved to the "To be Scheduled" list. Proposal 02B04 remains on the "To be Checkout" list since it has technical problems (power slope across the K-band bandpass and/or hardware limitations that would require 2-4x as much observing time as requested). Proposal 2C12 still needs some more checkout time, which we hope to get to in the next two weeks. I'll be going through all of the proposals to reassess which one can be scheduled in March/April or can be checked out in April/May. Karen has had a setback with Spectrometer mode checkouts in that ~12 hours of her data may not have been taken correctly. Since Karen is away for almost two weeks, we should try to schedule more time for mode checkouts in April. Frank, mostly, and I have been making good progress on the algorithm development for the ease-of-use/configuring-the GBT-hardware project. It'll be tight but I expect we will be done by our end-of-month deadline. -- RJM Discussion. Concerning Q-band commissioning, Al and Phil noted that atmospheric O2 lines will greatly increase Tsys and line absorption in the upper part of the 40-50 GHz band. Roger asked if the beam widths looked about right, and Ron replied that they did. Phil closed by congratulating all those who had worked on the Q-band project. It is both impressive and encouraging that everything worked so well the first time out. 4. Software status Software Development Division #28 - Friday, March 14, 2003 We are completing Week 1 of a 6-week development cycle, to culminate in the release of M&C v3.13 on 4/23/03 +/- 1 day. M&C v3.12 was released on Wednesday, March 12th on schedule, after regression tests and other independent verification indicated the health of the new version. RMS calculations for the active surface were updated, spectrometer software reliability was verified to be drastically improved, and the fix for the active surface 100ms problem was implemented and astronomically verified. Release notes are available at http://tryllium.gb.nrao.edu/release/MC_v3.12 and the regression report is forthcoming. On Monday, March 10th the Software Plan of Record was completed and approved by the program planning group. Release commitments for M&C v3.13 focus on completing the spectrometer improvements initiative that was started last summer, and completing another iteration of active surface improvements in support of the PTCS project. Complete details for this release are described at http://tryllium.gb.nrao.edu/images/POR_April03.pdf for both core and background activities. EMS work continues on schedule; a limited working example is now available which makes the group confident that the completed demo will be useful at the PTCS review in April. Out of the 7 MRs that comprise this project, 3 are complete and the remainders are in various stages of development, representing an expected level of progress. The SDD is also moving forward reviewing Frank's list of outstanding bugs from Bugzilla, moving towards its goal of completing all reviews and providing responses and/or high level level-of-effort (LOE) estimates on all 137 requests by the end of March. This is in support of the ease of use initiative. Once LOEs are in place, the SDD will work with the program planning group to divide and conquer the remaining bugs that have not been solved in previous cycles. The SDD requests that you submit all new software requests through the software Project Office at http://projectoffice.gb.nrao.edu and provide us with comments to help us make our system work better for you. You can also view and search the 137 aforementioned items from this location. -- NR Discussion. Nicole noted that a problem with the IF Manager in 3.12 had arisen during Glen's observing time, but has since been fixed. The "Requests" section of the the ProjectOffice has 137 entries, that include many of the bugs transferred over from Bugzilla. Those who had entered bugs in Bugzilla should browse the ProjectOffice Request list to see that all of the important entries were carried over. 5. AIPS++ report Joe reported that the external review of AIPS++ was conducted last week. An executive report from the review panel is expected early next week. Joe noted that he will be needing to spend more time on AIPS++ management, and the resource needs for Dish support of the GBT will require some attention. The way that the zero channel data of the Spectrometer is stored in the MS will be changed -- it will no longer be stored in a special bin of the spectrum. This should result in some performance improvements in some calculations (since spectra will have 2^N points rather than 2^N + 1). No changes on the M&C side are required. Joe and Steve will be in Green Bank from 8-16 April for the Visiting Committee Meeting and consulations with GB staff. 6. Spectrometer status The spectrometer is operating properly and we have a full complement of spares. All broken modules have been repaired and tested in the system. All of our system test time has been used checking the repaired modules in the system. Summary of problems found: LTA test fixture: Jitter in the 100 MHz oscillator was caused by bad contact in its socket (I think). The test fixture was modified to use an external oscillator which will allow testing over a frequency range. LTA S/N 9: Bad Xilinx chip LTA S/N 8: Intermittent memory control signal that fixed itself. No real cause found. System monitor: Fixed itself when re-inserted into system. Bad contact is the most likely cause. Efforts to make it fail again were unsuccessful. Sample Distributor S/N 5: Burned spots on the board either from shorted capacitors or contamination under capacitors were found. Also a shorted control wire from pin that got too hot and burned through the insulation was found. These were repaired. This board has a lot of corrosion on it so must have been exposed to a caustic solution at some point?? Plans for a new test signal source for the correlator were discussed with Rick and Karen. Requirements were modified as a result. A block diagram was drawn up. An M&C feature to more accurately specify the location of Xilinx Load failures was tested. It was shown that the log file correctly identifies the card with the bad Xilinx load, but that there is no mention of this detail in the message window. Additional testing of the multi-integration problems was conducted. Our logs show that the steps and spikes we saw in multi-integration scans were associated with LTAs which failed recently. The set of LTAs in the spectrometer now do not exhibit the multi-integration problem. The situation is similar with the slot sensitivity of the LTAs that we have seen lately. Possibly these are indications of an imminent failure. Plans for next week. Mode testing. Ray to come up and help investigate - the slot dependence problem in the LTAs if necessary - the multi-integration problem in LTAs if necessary - the low-level structure in the auto-correlation function - data frame problems in the pulsar spigot Discussion of plans for a new test signal source with Roger and Galen -- RL Discussion. Rich noted that the multi-integration problem now appears, fortunately, to be a board-level rather than system-level problem. There was a discussion as to whether a faster reset option might be available that avoided full shutdown. Most resets will result in a shutdown, but Rich and John felt that even a full shutdown and restart should be possible in about 5 minutes. A procedure for this has been written and given to the operators. 7. Project scheduling (From the Monday project meeting) 1) This week's schedule Decided to play the Q band scheduling and the M&C regression tests by ear, due to uncertainties in each. Approved with the exception of the M&C testing Wednesday. That will have to be coordinated so that the M&C software is not unavailable all day. [Subsequent happy events have rendered this moot, and required changes to the schedule to allow Q band calibration. See the resource calendar] 2) Next week's schedule Spectrometer test time on Wednesday and Thursday for Lacasse, Chen, and Escoffier to work on intermittent/wierd problems. M&C tests moved to Tuesday morning. Telescope weighing will start next week. Weather dependent, and will require people to be off the antenna while it is jacked up. Will require about 8 days of good weather to complete. 4) April Schedule Still holding the end of the month for the track welding test. 5) Softare targets for next cycle Amy presented the plan for the next cycle, and it was approved. This follows along the plan espoused where the focus is shifted to bug-fixing and user friendliness from new capabilities. Specific items to be worked are: PTCS Project: 4 FTE's Critical Design Review Support: 0.7 FTE Spectrometer reliability enhancements: 1.0 FTE GO Maintenance: 1.0 FTE Frank's Bug List: 1.0 FTE (in addition to the Spectrometer and GO effort, some of which is directed at Frank's bugs.) 6) AOB PF 2 Commissioning: This is scheduled for July. The receiver will be put up as soon as the pulsar monitoring project at the end of June is completed. 40-60 hours of telescope time will be required for this work. Telescope Summer Maintenance Schedule: The telescope will be scheduled for 4 12 hour maintenance days per week over the summer, beginning in May. This will allow better efficiency on the structural inspections, painting, and other rigging-intensive operations. -- JF Discussion. Phil added that PF2 commissioning was being set for July to make best use of the remainder of the high frequency observing season and to avoid conflict with other scheduled projects. 8. Observing schedule Last Week ======== Observations for GBT02B-018, GBT02C-007, GBT02A-031 GBT02B-018 was not completed because of Az track restrictions. March ===== Astronomy remaining ~ 180 hours Maintenance remaining ~ 93 hours April ==== Astronomy ~ 329 hours Maintenance ~ 152 hours Tests & Commissioning ~ 202 hours Shutdown (track work) ~ 39 hours May === Astronomy ~ 16 hours Maintenance ~ 197 hours (12 maint days) Shutdown (track work) ~ 24 hours Beginning Mar 12 Az track limits became more stringent because of the large crack deterioration in the wear plate. This may result in canceled observations depending on timliness of repairs. -- RCB 9. Any other business