GBT Commissioning and Operations Meeting 16 October 2003 AGENDA 1. Az Track Status & other telescope news -- Bob A. 2. Observing news -- Ron 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 REPORTS 1. Az Track Status & other telescope news * Measurements plan was critiqued for the track FEA yesterday. * Comments on our welding procedures, and overall welding strategy, were received from M&M yesterday, and we are reviewing them. No word yet from Hahn and Clay on contract records for the welding of the shaft assemblies. Strain gauging is still scheduled for the week of 10/27. Document search of our files continues. Other repairs on the structure continue. Welding on far side is complete. * Trial seals for the azimuth bearing are scheduled for delivery10/23 or 24; installation of the first set is tentatively planned for 10/28. -- RA 2. Observing news Observing since last Friday has pretty much been event free. Only 10 minutes of observing time was lost to a BCPM problem. More than half of the nine hours scheduled for observation setup was actually used for astronomy. That is, the time to setup the system has averaged to less than one hour. We lost 90 minutes of test time to Spectrometer, Spectral Processor, and FITS file problems. Another notable item from this week is that Toney rediscovered the antenna trajectory problem that occurs at the start of an observation. Due to the high winds yesterday afternoon, there's been a delay in warming up the receiver and we were able to use last night to finish the commissioning of the upper K-band system. The lower band should be completed this weekend. The results from the upper K-band tests show system temperatures at the zenith in the lower forties, notably lower than last year because of the new amplifiers. The calibration for both bands is much better than at the end of last season. We repeated a lower-K-band experiment from last spring and found baseline shapes that are now less curved than previously measured. The only problems so far encountered with the system is excess noise in the R1 channel. The cause of the problem is not known but we suspect that the problem lies after the beam switch. -- RJM 3. Spectrometer status - Spigot testing: Reproduced problem reported by Kaplan for Escoffier. Ray is looking into fixing it. Will require more test time. - High speed samplers: Good result by adding a filter and regulator board without modifying the phase-looked loop proper. Trying to reproduce this on other samplers - Continued work on LTA redesign. Received some help from Escoffier. -- Rich & Holly 4. Spectral Baseline, Front-end, and IF work Two recent observing sessions investigating the X-band baselines on continuum sources have been productive. At least two separate types of baseline structures are identified: fairly narrow (1-2MHz) structures that originate in front of the first mixer, and generally broad (>100MHz) structure that originates after the LO2 mixer in the common IF system. For brave souls, detailed reports are located in the directories: /home/users/groups/baseline/Projects/TBASERDN030926 and /home/users/groups/baseline/Projects/TBASERDN031010 Next week, we plan to pursue the stuff following the LO2 mixer, trying to isolate and understand the origin. Work on the Ku-band and Q-band continue. -- RDN 10/15/2003 5. Software status 6. Schedule Last Week ======= Observations for: GBT03C-029, GBT03C-008, GBT02A-031, GBT03B-026, Completed: GBT03C-008, GBT03C-029 October ====== Scheduled hours [backup] Astronomy ~ 307 [120] Maintenance ~ 132 Test & Comm ~ 307 November ======= Scheduled hours [backup] Astronomy ~ 270 [46] Maintenance ~ 102 Test & Comm ~ 230 [7] Shutdown ~ 36 Un assigned ~ 82 -- RCB 7. Project scheduling October 13th Planning Meeting Minutes **** Rm 241 OCTOBER 14th 8:30 A.M. **** [0] Discussion of Observer comments Frank again made a plea to get the HF phase cal signals working. Carl will consult with Frank on the importance of this issue. Ron's Holography problems were discussed. We dropped the ball by not having some time to check out the holography system before trying to do a holography run. That will be remedied today. Spectrometer balancing was discussed again, and we agreed that we need to get the 3 level balancing algorithm working again. Toney Minter reported a multitude of problems, most related to known software problems in GO. Other problems reported were: Bad data from the spectrometer. Spectrometer failed to stop on command IF Rack wouldn't balance Optical Driver 8 We also discussed Toney's comments on the antenna tracking problems. The upshot of this is that it seems that the antenna is not settled on source for some time after the start of the scan. Toney will be asked to generate some plots so that we can further investigate the problem. [1] This week's schedule Spigot card testing Tuesday afternoon and possibly Wednesday, depending on the results of Tuesday. We don't need anything but the spectrometer, so config testing can continue on other devices. Spectrometer balancing time will be made available Thursday morning. [2] October Observing Schedule discussions We talked about scheduling some antenna time to track a pulsar during the Jansky Lecture in Green Bank. Frank is handling the question of feasibility. [3] November Observing Schedule discussions Backup time for the high frequency projects is still needed. [4] GBT development planning 6 month forward look meeting Thursday, 9:30 to 12:00 [5] AOB Antenna tracking problems After a long discussion, it was noted that there are several possibilities here. We need to investigate the cause, that is, why is the antenna off source after the start time. We need to investigate the magnitude of the problem by looking at typical error vs time plots. finally, we need to have a method of dealing with the problems in the short term and long term. Toney has been asked to generate some plots demonstrating some of the problems. 28.75 Hz interference. Mike Stennes and Jeff Acree will have a look at the maser signal to determine if it is changed since the last observation. John will ask the pulsar observers to look in Spigot data for the same effect. K band noise and cryo problem Roger Norrod and Mike Stennes will be consulted to determine the problems with R1. We will attempt to get the refrigerator replaced this week, per Carl's request. Spectrometer balancing problems Mark Clark will work on getting the three level balancing to work again. The time on Thursday will be allocated to him. He also would like someone from electronics to work with him to validate that end of things once he thinks it's working. After that, we need an on-sky test with one of those pesky astronomers at the wheel. Measurements database failure The SQL server handling the databases for the telescope went down. Joe restarted it. John has asked Chris Clark to add as a task to his telescope independence project the addition of an SQL server inside the protected telescope LAN that will run all telescope database activity. -- JF 8. Any other business