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GBT Operations & Commissioning Meeting

25 May 2007

AGENDA

• Upcoming Activities -- Carl
• Az Track, Antennae Report -- Bob
• Observing News -- Ron
• Scheduling Status -- Carl
• Microwave Electronics Status -- Steve
  • Operations
  • Development
• Digital Electronics Status -- Randy
  • Operations, Problem Summary
  • Development
  • Plans
• Servo Systems Status -- John and Tim
• Software Status -- Amy
• Computing -- Chris
• PTCS -- PTCS Team
• Pulsar Related -- Scott
• MIT/LL 43m Project -- Glen
• Commissioning Plans -- Ron
• Any other Business

Upcoming Activities -- Carl

Az Track, Antennae Report -- Bob

Work progresses a little slower and meticulously (and quieter!)after all the demolition has been completed.

• Baseplates have been set in two octants, and the part growth due to welding that was observed in Savannah accumulates to cause a concern for alignment. While the amount is very small (5 parts per 100,000), at the circumference of the track it accumulates to nearly 1/2 linear inch. This could double after completion of the field welds. Our contingency plan was to make corrections when doing the tie-in welds in Phase 2, but we thought it best to address it incrementally now, rather than risk a major correction then. Our expectation of the contractor was to provide for this contingency, and they are in the progress of making the corrections. This isn't a simple effort: it requires nearly a half day of measurement and analysis to determine the correction needed. We've machined two octants worth of plates, and they are being placed yesterday and today, and if alignment and level are acceptable, we should release them for welding tomorrow!
• John Shelton has performed some sanity measurements behind SATCOM, and has a pretty good assessment of that effort. The present octant being measured has a level within 4 thousandths.

140': Preston restarted all of the systems successfully last night following the transformer installation, and we are in the process of replacing the broken brake spring. That should finish up late today.

Observing News -- Ron

Scheduling Status -- Carl

Microwave Electronics Status -- Steve

Operations

• Prime Focus and L band are in use with no problems to report.

Development

• Ka band testing revealed possible source of amplitude imbalance.
• Ka phase switching transients coupling to bias lines are being investigated.
• Andy Harris arriving Monday to assist with sorting Z spectrometer problems.

• X band is cool with stability testing and characterization set to begin.

• Second C band downconverter module construction is nearly complete and ready for test.
• Third C band downconverter module construction is 50% complete.

• Feed defroster upgrade continues with machined parts nearly complete.

Digital Electronics Status -- Randy

Operations, Problem Summary

Development

Plans

Servo Systems Status -- John and Tim

Software Status -- Amy

We are in the first full week of the fourth development cycle of 2007 which can be viewed at PlanOfRecordC42007.

Operational and user support was relatively light this week and included:

• Revived software after brief power outage.

Modification Requests:

• MRs released this week:
  • Update Pointing/Focus code to Handle Old Data Sets (ModificationRequest3C207)
  • Add Encoder Velocity to PrePoint Output (ModificationRequest3C307)
• MRs ready for integration/regression testing:
• MRs ready for sponsor testing:
  • Fix Inclinometer Data Collection Problems (ModificationRequest1C207)
  • Fix Accelerometer Timestamping/Data Collection (ModificationRequest2C307)
  • Quadrant Detector Timestamp Fixes (ModificationRequest5C307)
• MRs under development:
  • Modify Peak Finding Algorithm for Pointing/Focus Code (ModificationRequest4C207)
    • Currently testing convolution approach and comparing results on datasets to approaches called out in MR.
  • SCCU Servo Changes (ModificationRequest1C806)
    • Although the code is working, we have found that commanded velocity spikes occur during normal observing. To date this has not been a problem since the hardware filters out the spikes. However with the hardware modifications coupled with this MR, the spikes will corrupt the intended operation of the friction compensation. John is working on modeling a different methods of deriving the velocity commands.
• MRs under CCC review:
  • Add Two New ScanTypes: FivePoint and Circle (ModificationRequest1C706)
    • Not scheduled.
• MRs under sponsor review:
• MRs being written:
  • Port Holography Manager to Linux (ModificationRequest1C307)
    • No progress.
  • Create Pyrgeometer Manager (ModificationRequest2C207)
    • No progress.
• Other Activities:
  • Dynamic Scheduling - We have completed initial project pages containing project, allocation, and project account information. We are able to access the selection rules (I and II) from TurboGears and display the resultant sessions. We are now working on JavaScript "pull down" tables and integrating the SQLAlchemy ORMs for selection rules and TurboGears. Quite a bit of effort this week went into preparations for the upcoming internal staff review as well as the external review. Reminder that the internal staff review is scheduled for Tuesday, May 29th at 9am in the auditorium.
  • Analysis of Trajectory Generation Problems - Nothing to report.
  • Find/Fix Command Stream Glitches - On hold pending trajectory generation problem analysis.
  • Complete Pointing Processing Description Memo - No progress
  • Complete Documentation of Cross-Polarization Changes - In progress.
  • Evaluate GBT Data Handling Status & Future Options - In progress. We met last week with Nicole Radziwill and Joe McMullin to discuss the current state of CASA single dish data reduction.

Computing -- Chris

PTCS -- PTCS Team

• Engineering
  • Thinking about servo reqirements for next generation servo system.
  • Reworking plans

Pulsar Related -- Scott

Not a whole lot of development to report this week. We've been continuing to take data for more than the scheduled amount of time for the drift scan project. And that has made us go though all of the group's disks slightly faster than we had expected (especially since we were scheduled for more time than we asked for!). But yesterday we started the process to order between 100-130 750GB drives. So assuming that the first batch shows up in time, that should help us quite a bit.

As far as the data taking goes, we've been observing in the "hacked-calibration" 8-bit mode that Ryan and I came up with. In general, it seems to be working quite well and we are seeing the known pulsars that we should be seeing. Hopefully next week we have some time to make "real" Spigot calibrations work.

The pulsar meeting I thought was quite a success. There were lots of good discussions and many of us have new ideas for future work and collaborations.

Finally, Paul Demorest showed up in C-ville this past week. He's getting settled in now and we're going to try to spin him up on the new pulsar backend over the next 2 weeks.

PS: I will not be at the meeting as I need to go to be at a Drs appt with my wife.

MIT/LL 43m Project -- Glen

Commissioning Plans -- Ron

Any other Business

-- RichardPrestage - 24 May 2007