GBT Commissioning and Operations Meeting 29 August 2003 10am EDT AGENDA 1. Az Track Status -- Bob A. 2. Observing news -- Karen 3. Spectrometer status -- Rich 4. Spectral Baseline, Front-end, and IF work -- Roger 5. Software status -- Nicole 6. Schedule -- Carl 7. Project scheduling -- John 8. Any other business PRELIMINARY REPORTS 1. Az Track Status Most of the effort of the antenna and mechanical engineering group went to follow-up on structural inspections, so there is little to report on the azimuth track this week. 2. Observing news Observing report, 20-28 August, 2003 Five different observing projects took place during the last ten days, with the rest of the telescope time going to maintenance, hardware tests and PTCS. Two of the observing projects were pulsar projects (02C-060 - Nice and 02A-062 - Camilo) and both used the Spectral Processor backend. The 02C-060 project ran for 5 nights for a total of 27 hours and was occasionally plagued by impulsive RFI at about the 1.2 Hz rate. Jeff Acree tracked this down to an electric fence, which was turned off for the last 2 nights of the series. In the end 3-4 of the 7 observing sessions for this project were reasonably free of RFI. No problems were encountered during the 02A-062 observing run, which ran for four hours on one night. The other three observing projects (02A-031-Lockman, 03A-014-Lockman, 03B-030-Benjamin) were L-band 21-cm observations with the spectral processor. The spectral processor crashed a couple times during the combined total of 54 hours for the observations, which is consistent with the spectral processor behavior seen by this group in the past. It should be noted, though, that after a spectral processor crash, GO does not accurately reflect the state of the spectral processor, and if "observe" is hit without hitting, e.g. "prepare" in the spectral processor window, the observing parameters will likely be incorrect and will not match that seen in the GO window. -- KO'N 3. Spectrometer status There was a fairly successful test of the pulsar spigot system over the past weekend. A few bugs in a command used for setting gain and scale factors for data sent to the spigot were found and fixed. Data were taken in 1 IF, 16-, 8-, and 4-bit modes. Comparisons were made to data taken in parallel by the BCPM and Spectral Processors. Sample comparison data will be shown at the meeting. Certainly getting the first mode to work is a large part of the job; however only 3 of the 34 available modes have now been checked astronomically. An effort was begun to make use of idle spectrometer time to elicit clues about the DMA and other errors and to exercise recently modified hardware. In about 8 hours of testing, no DMA errors have occurred. The effort to document software requirements for the spectrometer's pulsar modes is continuing. In the process a variety of documentation has been improved. Upgraded all 10 LTA Boards. All boards have been tested in the system and on the bench. 8 boards passed self test both in the system and on the bench. Now all quadrants are upgraded with 32MHZ LTA boards. Upgraded interface card FIFO from 2Kx9 to 4Kx9. it passed self test both in the system and on the bench, now is running in the system. Nathan has is back on the task of upgrading the high speed samplers. Cables carrying 1.6 GHz reference signals are being upgraded to semi-rigid to reduce the interference emitted by the rack. -- Rich and Holly 4. Spectral Baseline, Front-end, and IF work Six ripple-compensated fiber modulators have been received back from the fiber splice contractor. Lab testing showed that two of these will have to be re-spliced - one due to an apparent laser diode going south, and the second due to a bad splice. However, testing is almost complete on four units, and they should be ready for installation in the next week or two. A day or two for in-system alignment and testing will follow before they are released for use. Replacement of the second set of four modulators will then begin. The first real feed tests in the indoor antenna range were accomplished this week, at 26-40 GHz on the feeds designed for the 1cm Receiver. Measurements on the same feeds were previously accomplished at a MIT range, so this provided an opportunity to compare our range performance. The initial results were pleasing and compared well with those from the MIT range. Sri and Gary identified and covered with absorber several parts of the range that were sources of reflections, causing ripple in the measurements (not unexpected for initial range setup). The dynamic range of measurements in our range is about 40dB, and with optimization of the setup we should be able to improve this further. Reflection tests on the C-band feedhorn were accomplished last week as follow-up to baseline tests on the GBT done earlier in the summer. A report is available on the "Baseline" web page at: http://www.gb.nrao.edu/gbt/baseline/subpages/reports/MiscReports/CbandFeedMe as.pdf In summary, reflections from the feed radome with various obstructions were quantified to allow comparison with baseline results on the GBT. We also found that the radome itself contributes a reflection at the -50dB level. While the receiver was off for these tests, Cryo found a broken refrigerator seal that had been causing erratic 2nd stage temperature variations. The K-band upgrade proceeds. Initial testing found quite good noise performance in most cases. However, one beam showed a fairly large noise peak in the middle of the band that has been isolated to the vacuum window. That unit is being rebuilt. Resonances were also found in the hermetic coaxial feedthrus which carry the RF signal out of the vacuum dewar. We are investigating the best way to replace these, as vacuum feedthrus that are specified to 26.5 GHz are not commonly available. Planning is underway toward a trial cooldown of the Penn Bolometer Array 300mK cryogenic system on the GBT during the week of September 22. --RDN 8/28/03 5. Software status Single Dish Development IPT #48 - Friday, August 29, 2003 This week ends Week 2 of the 6 week development cycle which is the 7th cycle in 2003. The Plan of Record for the current development cycle is available from the Project Office web site at http://tryllium.gb.nrao.edu/docs/POR/POR_Sept03.pdf. Today we are starting to track our progress using earned value metrics. Although we anticipate that the process will be refined from now until the end of the year as our understanding grows, today we can report that we have completed 33% of our progress measures in 32% of the cycle, meaning we are approximately on schedule. Activities for the current cycle include PTCS work on Python data displays, enhancements to the laser rangefinders, expansion of EMS to include the ability to include data from other parts of the telescope control system, several updates to support PTCS antenna characterization, the development of a configuration alpha from prototype developments over the past year, a new gbtlogview, validation of data preprocessing components, and continued support for electronics to resolve spectrometer issues. The Python scripts for az/el pointing and focus for PTCS were made ready for experiments on Tuesday evening, and work continued throughout the week which resulted in improvements to response speed but many more iterations are necessary before this will be ready for prime time use. Next week a framework will be developed so that the components are more interoperable, which will help solve some of the usability issues that have been noted with these experimental programs. This framework will also serve as the foundation for a new and improved gbtlogview to be released at the end of the cycle. Several AIPS++ pgplotter issues are being resolved at the moment; Ron recently approved Jim's MR describing four specific changes to be made. Additionally, an MR has been written and approved to make multi-IF data available from UNI-jr type functions in DISH. In addition this week, the L-Band notch filter fix has been patched in to M&Cv3.16 this week. Operational support this week has included participation in the PTCS trilateration experiments. -NMR 6. Schedule Last week ======= Observations for: GBT02A-031, GBT03A-014, GBT02C-060 GBT03B-030, September ======== Scheduled hours [backup]: Astronomy ~ 258 [120] Maintenance ~ 147 [48] Tests & Comm ~ 306 [15] October ======== Scheduled hours [backup]: Astronomy ~ 72 [7] Maintenance ~ 124 Tests & Comm ~ 134 Un assigned ~ 406 -- RCB 7. Project scheduling August 25th Planning Meeting Minutes Rm 241 10:00 A.M. <0> Observer comments None available online Richard prestage told of his PTCS experiments over the past few days. Things generally worked well, including the weather, and he got more good data than the whole rest of the year's observing. A couple of problems were the LO1 went berserk a couple of times, and the configuration gui didn't work right for X band. Pulsar observations went well the past week, with very good RFI levels at 300 MHz. Phil asked that the RFI group write an article for the newsletter on the RFI environment. <1> This week's schedule PTCS will be able to use Thursday for tests if the ultrasonic testing of the elevation axle is finished. It is currently scheduled to be finished on Wednesday. <2> Next week's schedule 8 hour maintenance days are scheduled for next week due to the holidays. Telescope Operations and possibly the shop will remain on 10 hour days for the month of September. <3> September Observing Schedule discussions We will tentatively allocate maintenance and possible overnight time to repair of the elevation axle joints to September 16th through 26th. We will revisit this after the ultrasonic inspection is completed later this week. <4> October Observing Schedule discussions K band observing will not be scheduled before October 15th. Possible delay in getting K band back on the telescope due to resonances found in some SMA connectors. <5> GBT development planning No comments on minutes of the meeting. Discussion of any Latest Ideas There were no ideas submitted to the WIKI this week. Phil brought up some things that have been on the back burner. We (Frank, Phil, and John) had a telecon with some people from Haystack who wished to get our support for installing a wideband VLBI terminal in Green Bank. This would be done with no cost or effort on our part. We saw no negative impact on GBT from this, so we told them that we would support that proposal. The Documentation project, a part of the ease of use initiative, has lain dormant due to other pressing business. Phil wondered how much of it would be useful in the context of helping to define the next generation of tools to be produced under the EOU initiative. Nicole said that Toney will be editing the GO keywords document to get rid of all the unimplemented features. Carl Bignell pointed out a few documents that would be of use to the observers: A document describing the RFI environment, and a report from the baseline group on the known problems and some solutions. Phil also suggested that we need to revisit the proposal queue and see if any of the proposals in there can be checked out and scheduled. Ka/Q band We have taken the following steps to ensure that both the Q band and Ka band receivers make progress this 6 weeks: 1) Gary Anderson will take on much of the Q band refurbishment tasks. 2) Randy McCullough will take on the task of designing the detector assemblies. 3) Chuck Niday will develop the control cards for the cal and phase switch signals. This will leave Galen free to concentrate on overall systems issues, and the dewar assembly. Cryo test for Penn Array W/O September 22nd This test is set up, and will not be affected by the possible elevation axle repairs. <6> AOB Power outage scheduling It seems that the best day for this is September 10th. From 4-7 P.M., the power will be off to the site. Antenna Range Dennis pointed out that Sri may not bring his feed here as soon as he thought, and so there may be some breathing room in the schedule. Nicole updated the progress of Michael Lacasse on the software. John stated that he' like to continue on and get this project off the books. It is one of the few remaining projects not covered by the project management system. K and Q band receivers Richard wanted to know if there was a test plan in place to test the K and Q band receivers before putting them on the telescope, in order to avoid any surprises. John agreed to mail Ron and Frank (Project Scientists) to make sure they had a plan to do this sort of test, including the data processing for these receivers. Design reviews Several projects are scheduling design reviews for the coming months. Penn Array Reciever is scheduling a CDR for early-mid October. PTCS review will be in the first half of November. A review of the Ease of Use program will be scheduled for early next year, as will the AZ track review panel. 8. Any other business