Minutes of the GBT Commissioning Meeting 31 January 2003 AGENDA 1. Az Track Status -- Bob A. 2. Spectral Baseline work -- Rick 3. PTCS project report -- Richard 4. K-band and other commissioning -- Ron 5. Project scheduling -- John 6. Observing scheduling -- Carl 7. Spectrometer status -- Rich 8. Software status -- Nicole 9. AIPS++/Dish status -- Joe M. 10. Any other business Reports 1. Az Track Status -- Bob Azimuth track work update: * A quantity of 10 plates are being ordered today (1/30/03) for the cracked plates and to use for the modification trials. * We are expecting engineering representatives here today (1/30/03) to inspect the track baseplate joint for the welding trial. * We have experienced a delay in the bolt strain tests.  The raw material used for the test piece was labeled as 17-4 PH, but was a           much softer stainless steel.  The test piece deformed during calibration.  New test pieces are being machined from confirmed (by hardness test)          17-4 PH, and will be ready for strain gauge mounting and calibration next week. * Lee King has begun a design calculation for plate attachments to the baseplates, and is working on the specification for the finite element analysis. * We have now inspected 14 of the wear plates during shimming work.  5 have cracks.  To date, we have found 15 broken bolts. [New crack found in plate 31 splice 30. Antenna will remain stationary in azimuth through Tuesday or Wednesday next week while this plate is repaired, and an accelerated inspection/shimming program implemented for remaining plates.] 2. Spectral Baseline work -- Rick The optical fiber stability was investigated with the IF noise source for a continuous period of 200 minutes. The even numbered optical driver modules (ODMs) were used consisting of an original external modulator, the new external modulator, and a direct modulator. Spectra were produced by calculating (Sig-Ref)/Ref where Sig and Ref consisted of either single records or groups of records taken at different times. The 2.4 MHz ripple was only detected in the original external modulator with a maximum amplitude of ~0.02% of the system temperature. The 2.4 MHz ripple appears to average out over longer integration periods. Further investigation is required to understand what effects the stability of the 2.4 MHz feature. The 60 MHz ripple, presumably related to the temperature variations observed in the equiptment room, does not average out in most cases is is clearly visible in longer integrations. Further observations of continuum source spectra at X-band do reveal that the irregular structure reported earlier is (i) similar in both polarizations; (ii) appears to be upstream of the first mixer; and (iii) roughly scales with continuum source intensity. Five minute on-off measurements toward cold sky reveal large frequency scale structures (few 100 MHz) with an amplitude of 0.05% of the system temperature. Recent observations were made with the K-band receiver (beams L1/R1 and L2/R2) using the IF noise source, cold sky, and continuum sources. There appears to be a significant instability in the total power in the first beam (L1/R1) detected in both continuum (DCR) and line (Spectrometer). Baseline structures with amplitudes of ~3% of the system temperature are observed with the first beam for both polarizations. Roger et al. plan to look into the K-band instability. Also, they intend to focus on isolation of the 60MHz ripple cause next week. [K-band L1/R1 beam instability might potentially have been ice or water on the radome. This will be checked over the weekend. If you have examples of poor baselines which you would like the baseline group to investigate, please send explicit details, including pointers to actual FITS files where the effect can be seen.] 3. PTCS project report -- Richard Work on the system design, Active Surface and Engineering Measurement System workpackages continues. Satish and Kim had an evening of PTCS time on Tuesday, which was used to obtain accelerometer vibration test data. Unfortunately, due to a problem with the Archivist's connection to the ServoMonitor samplers, no data were logged (the CLEO sampler displays appeared to be working fine). This test will be repeated next week. 4. K-band and other commissioning -- Ron There has been only one commissioning exercise this week. Frank, on Monday night, continued his work on Spectrometer mode checkouts. This finishes observations for all modes that have been on the checkout list plus a new one that last weekend's observers would have preferred. Frank found a few issues with regards to Aips++ and the filler that must be resolved before he can process the data and give the definitive OK. Our remaining time was mostly devoted to observer support. I sent out on Tuesday a lengthy description of the problems encountered during last weekend's observing. One significant problem, the power levels into the Spectrometer, have been worked upon but we have not had a chance to use the new hardware setup on test observations. I am starting to collect information from M&C and engineering on the costs of fixing the other problems I saw. Next week will be devoted to training, checking out the technical feasibility of some K-band proposals, and observer support. The rest of February will mostly be devoted to observer checkouts, observer support, and Spectrometer multi-mode tests. 5. Project scheduling -- John This week track work continued. More plates were inspected and shimmed. This will continue through a few more weeks, until all of the track has been inspected and shimmed. Baseline projects continue to take up considerable microwave group and scientific effort, along with telescope time. Tests are ongoing. This week we started planning our activities for the six months starting in the March-April time frame. This planning is starting with building a comprehensive list of projects, ongoing, deferred, and planned, and then taking that list and prioritizing it based on our objectives for the telescope. Once the project list is filled out, we will estimate the amount of effort required from each discipline, which will allow us to determine which projects can proceed, and which will be left for later. We will have a meeting with all the project managers to discuss this and decide the projects that will be undertaken next. [Reminder if you have equipment time scheduled and can't make use of all of it, please send an email to "gbt" to let others know.] 6. Observing scheduling -- Carl January ===== Astronomy - 51 hours (backup of 100 hours) Maintenance - 127 hours Tests+commissioning - 555 hours Finished 2 projects -GBT-0 2B-013, GBT02C-049 (radar exp) February ====== Astronomy - 225 hours (backup 222 hours) Maintenance 158 hours Tests+Commissioning - 266 hours Next week ======= Observations of GBT01A-014, GBT02A-008, GBT02A-052, GBT02C-033 March ===== Astronomy - 20 hours Maintenance - 147 hours Tests+Commissioning - 124 hours Will schedule ~ >120 hours of k band astronomy and ~ 40 hours of pulsar etc 7. Spectrometer status -- Rich Additional testing was performed to try to better understand the source of the low level structure in the auto-correlation functions (acf) of certain modes. Last week, a Xilinx chip in an LTA in the third quadrant was replaced. It was slower speed version than the rest of the LTAs Xilinx's. This cured a problem in the self test. This week we verified that it also cured the "low-level spike" problem in this quadrant. Some hardware debug of the spare spigot card was performed. It was found that a CLOCK_ENABLE signal was not being emitted from the xilinx chip on the board. Ray will be consulted before further action is taken. He was travelling most of this week. A meeting with Ron Maddalena was held to compare notes on checked-out modes. Based on his recommendations we have made a list of modes to check next week. These should satisfy the astronomical needs. We also need to see which xilinx personalities have not yet been exercised and see if those work. The duty cycle counts do not work correctly in 200 MHz mode. Most likely, there are errors in documentation produced by Lacasse in 1999. The documentation needs to be reviewed. This was started this week, but more work is required. It turns out that it is possible to run Shelton's pulsar spigot scripts if the Spectrometer Manager is turned OFF. These scripts were tested again. They produce data that is not quite correct. More work is required to isolate the cause. Another spigot test run was supported. Data frames with an improved way of ordering the data were tested for 8 and 4 bit, 1 quadrant modes. Plans for next week include tests of modes identified in the meeting with Maddalena, and tests to further isolate the cause of structure in the acf of certain modes. If not complete before next week, the 200 MHz duty-cycle problem will also be addressed. [Software support for spigot card testing is taking longer than was originally expected. The next two spigot test days will be used to explicitly attempt to get the scripts to run successfully. If this cannot be achieved, the for subsequent tests the spectrometer will need to be set up manually.] 8. Software status -- Nicole We are completing Week 2 of a 4-week development cycle, which will culminate with the release of M&C v3.11 on February 12, 2003 +/- 1 day. Out of our 9 release commitments for this month, 4 are in development, 4 are ready to test, and 1 (spectrometer duty cycles) has been handed over to Rich Lacasse to examine changes in the hardware that may not have been represented in the documentation. This investigation will determine precisely which changes need to be made in the software. Progress has also been made on some background tasks, including the Configurator GUI updates for K and Ku band, and the spectrometer quicktests activity. As of Friday, the SDD is slightly behind schedule due to operational support activities that came up this week, which amounted to 1.2 FTE of our effort for the week. These issues included restoring and resolving errors with gbtaio1, helping restore vortex and sadira after the machines went down, providing unexpected support for pulsar spigot card problems, and making sitetime, weather and PF2 operational after yed did not reenable them post-maintenance. A servo monitor bug that prevented data collection for PTCS was identified and investigated, but has not yet been resolved. The most critical operational support issue pertains to recent difficulties with the DCR; this remains our highest priority operational support issue and has supplanted any further work on the antenna trajectory preprocessor fix until it is resolved. All activities remain "green" except for two "yellows" - updating the FEM and the antenna trajectory preprocessor fix. FEM work moved more slowly than anticipated due to operational support responsibilities, but additional effort was added to this task on Thursday so we can bring it back up to green next week. The antenna issue is still under sponsor review, and pending satisfactory resolution of outstanding issues, can also be turned green again for next week. SDD members have spent time this week preparing for the GDAQ meeting on Friday, regarding hardware and software for new antenna instrumentation. Additional progress was made supporting Brian Mason for the Caltech Backend CDR, and we expect feedback from Caltech by the end of the day Friday. Work was undertaken to set up the infrastructure for an EMS development environment, including a directory structure and build mechanism. To further organizational development, a presentation on the software development methodology XP was given on Wednesday by Mark Clark to the SDD team. This was also attended by Bob Garwood and Richard Prestage, and resulted in lively discussion. February commitments can be reviewed by going to http://projectoffice.gb.nrao.edu and clicking on the February graphics on the left hand side of the screen. (Graphical status is available online at http://tryllium.gb.nrao.edu/status/20030131.html) 9. AIPS++/Dish status -- Joe M. o New Stable Snapshot should be available Tuesday. For details see: http://aips2.nrao.edu/daily/docs/reference/updates.html o January targets - bob gbtmsfiller: support bs data 30-jan-03 Done bob gbtmsfiller: support multi-beam data 30-jan-03 Done Complete. Changes as represented in Note 254. joe beam-switched imaging 30-jan-03 Pending further technical discussion. Initial imaging mode will be covered under "multi-beam imaging" target. joe beam switched calib refinements 30-jan-03 jim bs calibration refinements 30-jan-03 Generic calibration refinements occurred to better handle multi-feed,if data. The bs calibration refinements are deferred until the filler changes. sanjay multi-beam imaging 30-jan-03 Sanjay received the data for this last week. It will not make it into the snapshot but should be ready soon afterward. Added joe+ multi-if,feed,bank implementation 30-jan-03 joe calibration refinements (perf.,robust.) 30-jan-03 bob gbtmsfiller: multi-bank data in single MS 28-feb-03 Added target for next month's cycle. Full support for some multibeam modes are deferred until this occurs (e.g., Nodding). Calendar: GBT/AIPS++ Coord 2/10; Re-evaluate GO/IARDS communication 2/12; o User Support o Defects resolved: Use http://aips2.nrao.edu/ddts/ddts_main to examine AOCso04105 got an error message adding to a ms AOCso03941 previous problems leave import non-functional AOCso04096 multiple uses of import bombed AOCso04187 for OFFON scans the OFF scans are not calibrated AOCso04171 add exposure time to header to see averaged data AOCso04050 unexpected result for flat table AOCso03022 DISH: I averaged spectrum has wrong header info AOCso04028 write to file operation does not preserve the x-axis AOCso03839 writing optical velocities not possible (Defected:irritating flash). 10. Any other business [The "DCR" problem was discussed at length. As part of training, Ron and Karen will specifically attempt to reproduce the problem, and then to diagnose whether it is really occuring in the DCR, or elsewhere. This will be done using the current version of the DCR software. If the problem can be reproduced, appropriate staff will be called in to investigate further. SDD will circulate an email describing the symptoms, and how to revert to the previous release of the DCR if necessary. The short-term schedule for the next few days has been invalidated by the az track work. A new schedule will be agreed and released Friday afternoon.] R. Prestage 31 January 2003