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GBT Operations & Commissioning Meeting

16 June 2006

AGENDA

• Az Track, Antennae Report -- Bob
• Observing News -- Ron
• Scheduling Status -- Carl
• Microwave Electronics Status -- Roger
  • Operations
  • Development
• Digital Electronics Status -- Rich
• Software Status -- Amy
• Pulsar Related -- Scott
• MIT/LL 43m Project -- Glen
• Any other Business

Az Track, Antennae Report -- Bob

• • The mechanics shimmed 5 plates this week, and replaced no. 12 (one of the few remaining originals).
  • The shipment of teflon/bronze arrived this week and is in storage.
  • The painters made better progress this week, thanks to the weather and arrival of 3 more painters.

Observing News -- Ron

We supported 13 projects in 21 observing sessions. Average setup time was 13 minutes. The telescope was also scheduled for 42 hrs of maintenance.

Of the 14 operator shifts, 7 had no problems whatsoever, and 4 had only no-lost-time problems. We lost 1.26 hrs, a perfect 1% of the time scheduled for observations. The problems were:

• Spectral processor needed rebooting : 0.73 hrs
• Astrid (Grail needed rebooting, Astrid hung) 0.53 hrs
• No-lost-time failures: Spigot reboot, SDFITS filler, Spectrometer reboot, Astrid crash, L-Band Cryo

A minor amount of rescheduling prevented us from losing time due to the L-band cryo problem.

Scheduling Status -- Carl

Microwave Electronics Status -- Roger

Operations

The L-band receiver required a refrigerator replacement this week. No other problems were encountered.

Development

High Frequency Receivers: Work this week centered on the Q-band front-end, testing with the Lab Spectrometer. One beam has now been tested with the feed replaced with a circular waveguide load, while the other beam's feed was kept in place. We noted a significant decrease in the amplitude of short-period ripple (as a percentage of Tsys) with the waveguide load. We have also noted that short-period ripple is induced by small movements of ambient absorber sitting on the vacuum window over the feedhorn. Baseline effects due to the absorber movement is not surprising, but the short periods are not easily explained. Several experiments with negative results have also been done, which tentatively rules out some speculated causes. Thorough data analysis remains to be done, and plans are laid to further isolate the cryogenic amps.

Galen is at the MTT conference this week, so only some CCB related work has used the Ka-band.

C-band: Much of the cryostat fab drawings are now done and submitted to the shop, and several microwave components for possible use in the integrated electronics have been ordered for evaluation.

Digital Electronics Status -- Rich

***Operations, Problem summary***

There was a minor hiccup with the spectrometer that cost no lost time. Apparently a self-test resulted in an error message. Subsequent self-tests passed but the error message did not clear. Software may be able to add some insight into the problem. Perhaps we should put in a work order to check this out?

***Development***

Cal-Tech Continuum Backend (CCB):

While attempting to set up the 2nd CCB for lab testing with the Ka Band Receiver, we noted some anomalous behavior which was previously undetected. Basically, with the PC-104 board stack in place, we could no longer download personalities to the Master Card's platform flash memory. If the PC-104 board stack was removed, the problem disappeared. Subsequent testing uncovered a persistent occurrence of "framing errors" within the serial bit streams being downloaded. The unit was then dismantled, a previous hardware modification was re-worked, and the unit (sans its enclosure) was tested again. This time, everything worked perfectly; so, at this point, the plan is to re-assemble the unit early next week and resume testing with the Ka Band Receiver.

The Power Input Module in the original CCB was modified this week to make it identical to the improved power module in the second CCB

Lab Spectrometer

Operational problems with the spectrometer were resolved with some help from Ran Maddalena.

A justification for the purchase of a high speed oscilloscope was written and discussed by the group. We also set up a demo for a Tektronix scope on June 29th.

***Plans***

- Continue CCB construction...
- Evaluate Tektronix scope...
- Continue Active Surface maintenance...
- Continue ALMA support as needed...

Randy and Rich

Software Status -- Amy

This ends Week 5 of 6 in the fourth development cycle of 2006 which can be viewed at PlanOfRecordC42006. Integration testing is scheduled for Monday and Wednesday of next week. Regression tests are scheduled for Sunday, June 25. We plan to release M&C v6.4 on Wednesday, June 28. Release notes will be forthcoming.

Operational support was light for this week.

We attended a Zpectrometer meeting this week. In general, things are looking good. We spent a great deal of time in the meeting talking about software - specifically, the M&C Manager and GBTIDL/SDFITS data reduction requirements. As of this meeting, our schedule has slipped such that delivery of the Zpectrometer to Green Bank will occur around the first week in September.

We spent a lot of time this week reviewing and interviewing candidates for our open software position. Because the wiki is public, I will include no further details in this report but I will be happy to give an update at the meeting.

We are currently developing a project charter for balancing. The motivation for this project charter is to ensure that the individual balancing MRs conform to the overarching plan for balancing. The draft project charter is finished and under internal SDD review. We will then present the revised draft to the balancing sponsor, FrankGhigo. After getting Frank's nod of approval, we will present it for consideration to the CCC. It is important to handle our implementation of balancing carefully as it affects many parts of the system.

There is an item which requires some discussion. Last night, we got a call from Donna. She was concerned that the weather information in the CLEO antenna screen was not updating during a pulsar observation. Currently, the antenna updates the weather information used for refraction once at the beginning of each scan. (Actually the weather information is updated periodically, but not sent to the refraction model except at the scan start.) This could possibly be detrimental for very long scans which require up-to-date refraction information. We don't need to solve this problem at the meeting, per se, but we need to determine what (if anything) should be done in some forum.

Summary of Cycle 4 MRs:

• MRs ready for sponsor testing:
  • Add LST Capabilities to Scheduling Blocks (ModificationRequest14C306) (CCC approved)
• MRs with sponsor approval:
  • Create Linux Quadrant Detector Manager (ModificationRequest9C306)(CCC approved)
    • This will not be released this cycle. Work is almost complete. However, we will need to allocate some of Ray's time next cycle to finish. Currently, the Manager compiles and links, with new GDAQ library. We still need to add more parameters and samplers having to do with the DT-50 (heater/defroster). Summary of work remaining: DT-50 library, finish DDL, testing.
  • Allow Saving of Invalid Scheduling Blocks (ModificationRequest4C805)(CCC approved)
    • Because the LST MR (mentioned above) took longer than expected. The work associated with this MR will not be released this cycle.
  • Implement CCB Self-Test (ModificationRequest10C306) (CCC approved)
  • Software Fix for Spectrometer "Bad Lags" (ModificationRequest15C306) (Pending CCC approval)
  • Balancing Project:
    • Get, Set, and Change Attenuators (ModificationRequest8C505)
    • IF Rack: Change messages to indicate non-balance and non-linearity (ModificationRequest10C505)
• MRs being written:
  • Integrate F. Schwab's Antenna Trajectory Algorithm & Test (ModificationRequest2C306)
  • Create Penn Array Manager (ModificationRequest3C406)
  • Balancing Project:
    • Converter Rack: Add Ability to Set Power Levels and to Balance to those Levels (ModificationRequest4C505)
    • Change Spectrometer Warning Messages During Balance (ModificationRequest9C505)
    • Multiple sampling for Balancing procedures to diminish RFI effects (ModificationRequest11C505)

Pulsar Related -- Scott

The last two weeks have been big for pulsar support. I've trained three new Spigot users and helped them make their first observations (and then spent even more time explaining/demonstrating how to analyze the data!). There is a nice picture that shows my dedication here: www.cv.nrao.edu/~sransom/Scott_GBT_support_in_Banff.jpg That is me supporting Ginny McSwain?'s observation from the shore of Lake Louise in Banff, Alberta. And no, I'm not joking!

There have been a ton of Spigot observations in the last couple weeks, but now that I've gotten most of the observers to use some new software that I've written to convert 16-bit lags to 8-bit spectra (and for S-band data, to automatically chuck the bad 200MHz). That decreases the data volume by a factor of 2-3 and makes dealing with it significantly easier (the processing and backups go much quicker).

I've been talking to many people and building support for the next-generation GBT pulsar machine. There is lots of interest from UBC (Stairs), WVU (Lorimer/McLaughlin), DRAO, and possibly others. It would help if NRAO could hire a hot young digital engineer (with lots of DSP and FPGA experience)... For dollars, WVU and I will likely submit an NSF grant in the fall.

Finally, I got lots of good feedback about the AAS GBT pulsars talk -- I think a lot of people were impressed with what the telescope has done. And on a related note, the magnetar paper was accepted by Nature 2 days ago (Thanks to all for the high frequency support and for helping us to get on the telescope so quickly).

Next week I'll be at the Chandra proposal review in Boston for most of the week and expect to get nothing useful accomplished.

MIT/LL 43m Project -- Glen

John Ford and I swapped a hard drive for a VME computer in the MIT/LL trailer. This was successful. Tracking only on Thursday and Friday, but the computer failed on Thursday morning.

Next week, John Taylor and others from MIT will be upgrading the RF side of the trailer and installing a new computer. May not track again until Friday.

Any other Business

-- RichardPrestage - 15 Jun 2006