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GBT Operations & Commissioning Meeting

11 July 2008

GB137 and by video-con from CV-Conf

AGENDA

• Upcoming Activities -- Carl
• Operations
  • Scheduling Status -- Carl
  • Observing News -- Ron
  • GBT Telescope Operations -- Bob
  • Mechanical Division Operations -- Dennis
  • Microwave Electronics Operations -- Steve
  • Digital Electronics Operations -- Randy
  • RFI Group Operations -- Ron
  • Software Operations -- Amy
  • Computing and Network Operations -- Chris
  • Business Services -- Mike
  • 43m Operations -- Glen
• Project and Development Work
  • Dynamic Scheduling -- Karen
  • MUSTANG -- Brian
  • PTCS program -- Marty
  • CICADA program -- John
  • Ka-band Rx / Zpectrometer -- Galen
  • K-band Focal Plane Array -- Steve
  • Other Project Notes
• Upcoming Meetings
• Any other Business

Upcoming Activities -- Carl

Operations

Scheduling Status -- Carl

Observing News -- Ron

Over the last two weeks, we supported 32 projects in 75 observing sessions, including 4 VLB sessions. After prorating for the extra summer maintenance, the number of observing sessions is about 50% higher than was typical before our DSS tests. The telescope was also scheduled for 75.5 hrs of maintenance and 1.75 hrs of PTCS tests. Lost time was low (0.9 and 3.6 hrs for the two weeks) and dominated by observer 'no-shows'.

• Observer No Shows (5 instances) - 3.1 hrs
• Spectrometer (Setup and DMA/Reset problems) 0.5 hrs
• Astrid (2 instances) - 0.4 hrs
• GASP - 0.3 hrs
• Az Transducer - 0.1 hrs
• RFI tests - 0.1 hrs

The RFI tests are discussed below.

GBT Telescope Operations -- Bob

Mechanical Division Operations -- Dennis

• Installation of diaphragms in structure under the actuator room is ongoing.

Microwave Electronics Operations -- Steve

• All parts for S band received from machine shop. The receiver is being assembled with cool down expected next week.
• Previous weeks testing of IF system didn't reveal any problems. X band problems resolved?

Digital Electronics Operations -- Randy

• Jason and J.D. spent a considerable amount of time over the past two weeks sorting out IIOP module addressing problems with the Active Surface. Replacing the base on IIOP0; then reprogramming the addresses of IIOP0 and IIOP2 eventually cured the problems.
• Accelerometer #4 (at the vertex) had been temporily mounted using clamps and was suspected of having come loose. Inspection proved otherwise; however, as a precaution, the unit was bolted in place permanently.
• J.D. discovered that a circuit breaker in the Receiver Room which powers the Quadrant Detector illuminator had tripped. Once the breaker was reset, the QD began functioning normally again.
• Our summer hires spent most of their time inspecting and repairing actuator cables as required.

RFI Group Operations -- Ron

L-band observers have been noticing for years occasional baseline problems that last a few seconds but occur rather infrequently. This has been attributed to out-of-band RFI from an unknown cause that places the receiver into compression. Carla and the RFI group thought they had a strong possibility and coordinated observations of the RFI as seen by the monitoring station and GBT. A few minutes of Karen Master's project were used for the test. Unfortunately, when the source of RFI was transmitting was not the instances when the astronomers were seeing the RFI. The group is looking into other possibilities.

Software Operations -- Amy

• Operational Support:
  • Fixed Sitetime and gbweather SBC network routing
  • Cleared old Antenna Characterization messages
• PlanOfRecordC52008
• MetricsC32008 now available

Computing and Network Operations -- Chris

Business Services -- Mike

43m Operations -- Glen

• Mike Shields and John Cortney, of MIT/LL, came to GB and made some repairs of the electronics.
• We swapped the 1.5 to 3.0 GHz feed with the 0.15 to 1.7 GHz feed and reviewed their range measurements.
• Running calibration tests today and will start regular tracking after that.
• Plan many tests with 43m this weekend.

Project and Development Work

Dynamic Scheduling -- Karen

• Accomplishments:
  • We have made considerable progress toward a new window/fixed conflict resolution system
  • We are currently identifying "knots" which need to be untangled before the algorithm can run successfully
• Concerns:
  • We had a number of no-shows this week (4), resulting in some lost telescope time (~2.5 hour) *No shows were due to
    • Observer did not put in vacation plans; too much time spent in trying to contact him (faulty phone numbers); This happened twice for the same observer, in spite of contacting him in between (2 hours)
    • Observer was unaware of being scheduled due to large scale internet failure; Next project observer phone number was difficult to decipher by the telescope operator (0.5 hr)
    • Unknown why observer did not show (10 minutes)
  • Lost time was higher than it should be as we have a very limited number of backup projects; Also we may wish to think about requiring observers to contact the operators well in advance of their projects (e.g. 30minutes in advance) to allow more time to find a backup when a no show happens
• Coming up:
  • Continue work on windowing algorithm
  • Continued bug/enhancement fixes
  • Beginning work to compare measured Tsys, opacity with predicted

MUSTANG -- Brian

• First iteration CLEO screens reviewed
• Plan to install CLEO on Spider at UPenn

PTCS program -- Marty

• Servo
  • Ongoing work on deployment strategy and schedule
• Surface
  • An 8-hour set of continuous Q-band OOF holography maps taken on January 12, 2006 has been re-reduced and re-plotted, showing the effect of Sun on the dish during a clear winter day. The implied total surface rms error is consistent with changes in Ka band efficiency noted by outside observers.
  • Completed photo survey of selected actuators which revealed an assortment of 0.75 and 0.95-inch shims, most likely installed by RSI on the basis of theodolite measurements prior to the photogrammetry run.
  • S/N measurements of the traditional holography system are underway using input signal levels simulating a satellite spectrum. Seeing about 1 deg rms phase computed over a 1-minute sequence of 1700 * 35 millisec integrations. This performance is maintained out to about 30dB off-source with the Test channel. However, a large phase vs. temperature coefficient seen in overnight scans is currently being investigated.
  • Application of quadrant detector data to windy Mustang scans on Mars using Paul's empirical model is showing promising results in the image plane.
  • Attempt at taking half-power tracks with quadrant detector data on July 1 was thwarted by failure of QD, which was later traced to a tripped circuit breaker. Cause is still unknown.

CICADA program -- John

• GUPPI
  • Randy and Jason fixed the data pipe problem using various trickery and sleight of hand.
  • Another problem showed up in which all samples are negative.
• CICADA
  • Nimish Sane, Graduate Student at U Maryland is here for 2 weeks to begin work on dataflow modeling and design of a digital downconverter for the iBOB based sampler of GUPPI. This will be applicable to other spectrometers as well.
  • WVU received their clone of "beef", to be named "tofu". It will live in the tape room until further notice.
  • Working on papers for URSI and the CASPER workshop in August.

Ka-band Rx / Zpectrometer -- Galen

• Nothing new to report.

K-band Focal Plane Array -- Steve

• From hardware video conference this week set upon September for two commissioning periods of eight hours separated by at least one week.
• Commissioning time is requested for October for a repeat of September tests with better weather and focus on efficiency across the band.
• Pipeline video conference scheduled for July 24.

Other Project Notes

Upcoming Meetings

Any other Business

-- RonMaddalena - 10 Jul 2008