Minutes of the GBT Commissioning Meeting 7 February 2003 AGENDA 1. Az Track Status -- Bob A. 2. PTCS project report -- Richard 3. Spectral Baseline work -- Rick 4. K-band and other commissioning -- Ron 5. Spectrometer status -- Rich 6. Software status -- Nicole 7. AIPS++/Dish status -- Joe M. 8. Project scheduling -- John 9. Observing scheduling & report from Feb 3 proposal deadline -- Carl 10. Any other business Reports & Discussion 1. Az Track Status * All 48 wear plates have now been inspected.  13 plates have one or more cracks, of which, 4 plates are serious and are being monitored. * No change in the long, top surface crack on plate 44. * Plates are on order - expecting the first 3 the week of 2/21. * Several discussions this week with each of the welding and machining companies.  A demonstration criteria document has been created and will be sent to them today.  There is a serious engineering issue with being able to perform a post weld heat treatment without damaging the grout underneath the joint.  This will be investigated during the weld demonstration. * Bolt strain test was done yesterday.  Data being reduced and converted to stresses and strains. * Dennis and Bob are working on design of wear plate geometries for the trial. * I had a discussion with a metallurgist this week - he confirmed a number of our assessments about the conditions of the wear plates, and the need for PWHT for the base plate weld.  His opinion is that there may be a material better suited for the wear plate. * Dennis is planning to go to Germany next week to observe their track welding repair. -- RA Discussion: Dana asked if the new wear plates would affect pointing. Bob answered that efforts would be made to level the new plates through shimming or other techniques. Questions were also raised about clarifying ranges of restricted azimuth motion, the procedure for the high frequency / low frequency dynamic scheduling scheme, and the procedure for using the active surface. Carl and Bob will address these matters and communicate them to the operators. 2. PTCS project report Work on system design continues. The specs for the small foot-print data acquisition system and the EMS charter have now been reviewed. A monthly project review meeting was held on Wednesday; the goal of a Conceptual Design Review in early April is considered challenging but achievable. Jim Condon will be visiting GB Friday to start work on past commissioning data. Next PTCS commissioning time is Wednesday 12th February. Discussion: Richard noted that because of the nature of the project work, there was not always a great deal to report on PTCS on a weekly basis. In the future, we will not include PTCS as a weekly agenda item in this meeting, but will have reports when warranted. 3. Spectral Baseline work Galen and Roger used the spectrometer on one day to attempt to isolate sources of sinusoidal baseline structures that have been observed from time-to-time. The results were not conclusive, but they did see a strong effect linked to variations in electrical length of cables connecting various subsystems. They are now modeling this mechanism and studying whether it is of concern in system operation. Work on the C-band LNA replacement continues - it has been slowed by other work. Several improvements to the total power stability of the Ku-band receiver have been made, and lab testing continues. Old 140-foot data taken with the spectral processor were analyzed for the purpose of comparing spectral baselines with the GBT. Observations toward continuum sources were made at L, C, X, and K-band. At least the X and K-band GBT receivers were being used at the 140-foot at this time. For strong continuum sources the major feature consists of the ~11 MHz ripple due to feed/subreflector reflections. The GBT X-band baseline structures have a similar amplitude to those in the 140-foot data, but some GBT spectral features are more narrow than any observed at the 140-foot. We think that these should have been visible in the 140-foot data. Currently, we are thinking about what could be different in these systems. Hypotheses regarding coupling of the waveguide thermal gap to dewar resonances and possible resonances in partially contacting feed ring joints are beginning to be investigated. Analysis of a bit of low-K-band data from baseline tests of Monday, 1/27/03, which immediately followed the Carilli and Walter run that weekend, showed this receiver to be reasonably stable in all four channels L1, R1, L2, and R2. Hence, the L1/R1 instability we saw on Wednesday, 1/29/03, was probably unrelated to the baseline difficulties experienced by Carilli and Walter (still no baseline examples forthcoming from observers or commissioners on that observing run). Inspection of the feed 1 and radome later in the week showed no noticeable problem other than moisture on the radome due to rain on the day of inspection. We received reports from both Rich Bradley and Marian Pospieszalski on calculations of receiver noise temperature frequency dependencies using plausible impedance mismatches. We will be discussing ways of connecting their findings to specific GBT receiver measurements. -- JRF Discussion: Phil noted that Ron and Jim had processed about 4 hours of Spectrometer data in 200 MHz BW mode, which had yielded a pretty flat baseline. A 4th order polynomial had been removed, but the variations were smooth. Rick noted that in his tests, a 4th order polynomial would fit the baseline over 200 MHz, but would not always provide a good fit over 800 MHz bandwidths. 4. K-band and other commissioning There were only a few commissioning activities on the telescope since last Friday because of the hiatus with the telescope. The tasks consisted of: o Training Karen O'Neil in the use of the system. The training was with a stationary telescope and, as such, were not as wide ranging in topics as we wanted. But, it looks like Karen will be able to solo soon. o Observing checkouts of proposal GBT02B-002. I've reduced half of the data and determined that 4 hours of integration with the upper K-band system using beam-switching and the 200 MHz Spectrometer mode produced very usable spectra for their project. After I reduce the remaining data, the results will be sent to the PI's after which we probably can schedule this proposal. o Tests to recreate the DCR/K-band receiver problems discussed at our last meeting. Five hours of test with the telescope at access and 1 hour with the telescope at various elevations did not show any problems. o The commissioners, Jim Braatz, Toney Minter, ... meet on Tuesday to discuss how we can make the telescope easier to use by astronomers. This is the first step in a rather long process before things will start to change. I think the meeting was very useful and we came away with a number of action items. More meetings are planned. o Observing support for Mort Roberts et al and Harvey Liszt et al. Next week I've planned for more observing checkouts and observer support. -- RJM 5. Spectrometer status Little work was accomplished this week since Holly was at a conference and Rich concentrated on the Feed Arm Servo. There are a few things to report. - With regards to the failed pulsar spigot card, the Xilinx chip has been eliminated as a possible cause of the failure. - With regards to duty cycle problems in the 200 MHz band, several candidates for the cause of the problem were eliminated: sampler set up, sample distributor set up, duty-cycle read-out hardware. The most likely cause (as unlikely as it is) at this time is the software which configures and reads out the duty cycle monitor. Further progress on this item will take some joint work by hardware and software engineers. - Another pulsar spigot test run was supported. We re-verified 18, 8, and 4-bit modes using a pulsed sine-wave generator. We verified the 16 bit mode using the Cal Tech artificial pulsar. We successfully tested a few commands to the pulsar spigot cards from the VME computer. -- RL Discussion. Richard asked what the consequences to observers were for the duty cycle problem described by Rich. Rich stated that one could not set the power levels in 200 MHz mode with this problem (for multi-IFs). Rich stated that he and members of the Software group would get together next week to see if they can solve this problem. 6. Software status We are completing Week 3 of a 4-week development cycle, which will culminate with the release of M&C v3.11 on February 13, 2003. Out of our 9 release commitments for this month, 8 are being tested in preparation for regression tests which will begin Sunday night. The remaining 1 (spectrometer duty cycles) has been dropped. This issue was handed to Rich Lacasse over a week ago for review after detailed investigation of the code by three members of the SDD did not reveal any software errors. Rich concluded that the error does not seem to be caused by the hardware either. Both groups have exhausted their solution options at this point, so the activity will have to be resumed at a later time. Several other items from the background list have also been completed and are in test, including: updates to the Configurator to support K and Ku band configurations, the doppler issue with the LO1, beam selection in GO, and planet pointing. Detailed descriptions of the changes that are being made are available for review. As for operational support, investigation into the recent DCR issues was abandoned due to lack of reproducibility. All activities remain "green" except for two "yellows" - updating the FEM and the antenna trajectory preprocessor fix, identical to last week's report. Staff effort early next week will focus on tying up the loose ends in preparation for Thursday's release. SDD member Ray Creager led a review of the EMS Project Charter this Wednesday, attended by much of the software group plus Kim, Richard and Don Wells. The framework for the project was discussed so that the SDD can now begin design and development of the first incarnation of the algorithm development platform. Several members of the SDD also attended the PTCS project meeting this week, where our work on the Active Surface and Antenna Instrumentation was reviewed in addition to PTCS. 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. -- NR Discussion: Jim asked if the Configuration Tool would set up both beams of the K-band receiver. The answer appears to be no, but will be clarified. Ultimately, it needs to configure both beams. 7. AIPS++/Dish status o New Stable Snapshot. For details see: http://aips2.nrao.edu/daily/docs/reference/updates.html o Targets ----------------------------------------------------------------------------- Key: done Target completed add Target added during cycle (or during previous cycle) inc Target incomplete early Target delivered early postponed Target Postponed during cycle dropped Target Dropped from development cycle ----------------------------------------------------------------------------- status name target deadline completed done add george calibrater performance improvements 80 28/2/03 george ALMA Phase II support 80 28/2/03 kumar ALMA Phase III support 80 28/2/03 inc joe migrate glish access utilties 40 28/2/03 daniel variable shaped spw in ms2archive 120 28/2/03 daniel variable shaped spw in archive2ms 120 28/2/03 george flag scope:flag based on average 80 28/2/03 kumar spectral-line velocity imaging across spw 60 28/2/03 darrell combobox mega-widget 40 28/2/03 darrell reference counting defects 80 28/2/03 david msasraster: enable display of multifeed data 80 28/2/03 david msasraster: pixel identification 80 28/2/03 bob gbtmsfiller: multibank data to single MS 80 28/2/03 joe gbtms average/decimate routines 40 28/2/03 george high freq cal ii:opacity, gain, ant pos 20 28/2/03 sanjay spectral-line velocity imaging across spw 60 28/2/03 bob gbtmsfiller: support weight spectrum 40 28/2/03 jim iards: display 1 spectrum/spw 40 28/2/03 jim iards: append to one ms 40 28/2/03 early postponed bob gbtmsfiller: document 40 30/3/03 george ms tool improvements design 80 30/3/03 dropped tim joint sd/int calibration scaling 80 28/2/03 tim full joint sd/int deconvolution 80 28/2/03 george auto reject of solutions below snr 40 28/2/03 george reject intervals with insuff data 20 28/2/03 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 AOCso04292 the tsys values in the dish header are incorrect AOCso04118 after issuing newpage, plotxy1 does not label axis AOCso03963 only returns radio velocities AOCso03444 seems to be an intensity problem -- JMcM Discussion: Joe and Steve are coming over to GB tomorrow (Saturday) and will be in the lab from Monday through Wednesday next week. 8. Project scheduling Much of the telescope time this week went to track repairs and servo system RFI reduction. The weather cost us a full day of work in the receiver room, which translated into some lost telescope time. The baseline project's time was disrupted by the track and servo repairs. PTCS structural vibration tests were likewise delayed. We met this week and discussed the 6 month forward look. We will meet next week to go over the list and decide priorities based on staffing loads. The preliminary list follows below (comments welcome). GB Priority projects (in quasi-priority order) 1. Azimuth Track 2. Operational & useability enhancements complete Spectrometer checkouts Configuration Tool / user interface critical bug (hardware or software) resolution (things impeding observing) continued robustness improvements of Spectrometer, DCR documentation 3. PTCS 4. Spectral baseline improvements Implementation phase 5. Q-band Rx initial engineering checkout 6. K-band Rx upgrade 7. Ka-band Rx 8. Common MM Converter Background projects requiring/deserving some effort (no priority order) o Caltech backend support o Penn array support (occasional review) o W-band Rx o Beam-forming array o RFI reduction program: Work with Dormitory contract to ensure quiet devices are used Laser Rangefinder retrofit JL Shielded Room improvements -- doors, floors, walls o Spigot card support o Pulsar timing mode o Spectrometer Polarization modes o Fix Tipper data processing Move to manager, put in sampler o Fix Atmospheric Phase Interferometer. Science projects o Wideband Spectrometer study group o Science with Penn Array - JF 9. Observing scheduling & report from Feb 3 proposal deadline Last week ======= Most of the time went to Telescope track & RFI work (~64 hrs) Two projects observed: GBT02A-052 & GBT02A-008 First week of "pseudo" dynamic observing proceedures February ====== Astronomy remaining ~ 170 hrs Maintenance remaining ~ 108 hrs Tests & commissioning remaining ~ 220 hrs March ===== Astronomy ~ 332 hrs Maintenance ~ 146 hrs Tests & commissioning ~ 267 hrs Other ==== Feb 3 Call for Proposals - Received 35 proposals for 1421 hrs Three of the proposals are background using non moving telescope for 346 hrs Top 3 most popular frequencies (higest to lowest): L, K, 850 MHz Now available: An additional file for schedules which graphically displays low frequency secondary projects that are scheduled. -- RCB 10. Any other business Glen noted that a number of the glish scripts used to set up pulsar observations have the IF modules and other components used hardwired into the code. The components in use change with time, so the glish scripts have to be modified accordingly. The information about components is contained in the Cabling file. The best fix to this problem will come when the pulsar backends are fully integrated into the system and utilize the Cabling file. In the short term, the users will have to keep editing the glish scripts, or make the glish scripts able to read the Cabling file and use the right components automatically. PRJ 7 Feb 2003