GBT Operations & Commissioning Meeting
AGENDA
Activities List
We supported 17 projects in 38 observing sessions, a heavier load than typical. The telescope was also scheduled for 15.5 hrs for maintenance, 1.5 hrs for VIP tours, and 1 hr for receiver checkout. Lost time was completely dominated by high winds:
- Weather Problems (27.2 hrs, 17.9%)
- Winds : 27.1 hrs
- Rain (2 instances) : 0.1 hrs
- Observer Problems
- Late for observing : 0.2 hrs
- Software/Hardware/Operations Problems (5.8 hrs, 3.8%)
- Broken track scrappers & track bolts : 2.6 hrs
- Spectral Processor (4 instances) : 0.7 hrs
- Standard Cabling edits not loaded (2 instances) : 0.7 hrs
- Astrid (4 instances) : 0.6 hrs
- Active Surface (2 instances) : 0.4 hrs
- GFM (2 instances) : 0.3 hrs
- Turret wouldn't lock for L-band : 0.3 hrs
- Dynamic Corrections off (operator error) : 0.2 hrs
- Spectrometer (2 instances) : 0.2 hrs
The two GFM errors were software related, not the more typical attempt at pointing in bad weather. The weekly average of lost time from Astrid since the January M&C release is essentially the same as before the release. This is the 3rd time in a month that lost time could be attributed to standard cabling not being loaded after a change was made.
Last Week
=========
Observations for proposals
GBT07A-042, GBT07A-031, GBT06C-051,
GBT07A-098, GBT07A-021, GBT06B-042,
GBT07A-100, GBT06B-044, GBT07A-037,
GBT06C-056, GBT06C-045, GBT07A-016,
GBT06C-003, GBT06C-048, GBT06C-105,
GBT06B-018
Completed proposals
GBT07A-042, GBT07A-031, GBT07A-021,
GBT06B-044, GBT06C-048
Next Week
=========
Observations scheduled for **
GBT07A-041 [ P ] Antonio Crapsi
The temperature structure in the Vello prototype
L1014
GBT06C-051 [ P ] Lincoln Greenhill
Monitoring 2 NGC4258-like Masers: Measurement of
Distances / Constraint of LCDM
GBT07A-098 [F ] Fernando Camilo
Studying the magnetar XTE J1810-197
GBT07A-034 [ P ] Jim Braatz
The Megamaser Cosmology Project: A Survey for H2O
Masers in SDSS and 2MRS AGNs
GBT07A-023 [F B] G. Welch
The First Survey of HI in a Volume-limited Sample
of Elliptical Galaxies
GBT07A-100 [ P ] Pat Thaddeus
Search for the anions C4H- and C8H- in TMC-1 and
additional observations of C6H-
GBT07A-101 [ P ] Clive Dickinson
Ka-band CCB high-resolution mapping of spinning
dust
GBT07A-058 [F ] Jane Greaves
Cyclotron emission asociated with exo-planets
GBT07A-015 [ P ] Jeff Mangum
Formaldehyde Densitometry of External Galaxies
GBT06C-056 [ B] Pat Thaddeus
Search for the Five-Membered Aromatic
Heterocyclic Ring Pyrrole (c-C4H5N)
GBT06C-045 [F ] David Champion
A Search for Radio Emission from Magnetars after
Outburst
GBT07A-037 [ B] Karen O'Neil
Further Observations of HI in Galaxies and
Environments
GBT07A-038 [ P ] Jane Greaves
Detecting grain growth around T Tauri stars
GBT07A-016 [F B] Jennifer Donovan
How "Dry" Are Dry Mergers?
GBT06C-003 [ P ] Tony Remijan
Additional Transitions of Interstellar Methyl
Isocyanate (CH3NCO)
GBT06B-015 [ P ] Larry Morgan
NH3 and CCS Mapping of Triggered Star Formation
Regions
GBT07A-080 [ B] Maura McLaughlin
Continued Radio Timing Observations of RRAT
Sources
GBT06B-018 [ B] Michael Kramer
Timing and General Relativity in the Double
Pulsar System
BB241 [F ] Michael Bietenholz
Proper motion of 3C 58's pulsar
** Scheduled as F-ixed, P-rimary, B-ackup
Contact Information for 05/03/2007 - 05/17/2007
=======================================
Proposal PI Bands Email [NRAO contact]
---------- ------------------ ----- --------------------
GBT07A-053 Dunc Lorimer 3 Duncan.Lorimer@mail.wvu.edu [Toney Minter]
Scheduled hours [backup]
========================
Category/Month-> April
Astronomy ~ 628 [149]
Maintenance ~ 53 [017]
Test & Comm ~ 39
Un-assigned ~ 0
Proposal Checkouts #[hrs]*
=========================
Awaiting checkout - 0[0]
Active checkout - 0[0]
On Hold - 12[341]
Schedule - 72[1641]
Completed - 454[6244]
* All but completed queue applies to GBT only proposals
Current backlog [hours prior to 07A*] = 975
[2003:3(1), 2004:40(5), 2005:405(16), 2006:522(33), 2007:5(1)]
Backlog includes 67 hrs of monitoring projects
187 hrs of vlbi projects
Total time to discharge [hours] = 5408
Includes 137 hours of monitoring after trimester 07A
3137 hours of Large proposals
770 hours of Track Refurbishment proposals
247 hours of VLBI proposals
* Includes projects that are on hold for trimester 07A
Installation of 340 MHz PF feed.
Problems
Analog Filter Rack power supply failure due to site power interruption.
- Added an additional power supply to source more current.
Low power output from ORM#4 spigot B.
- Replaced ORM#4 with spare.
50 Mhz baseline ripple optical link #5.
- Problem not reproducible after ODM#5 replacement two weeks prior. Released for use.
Cband downconverter has been tested and report with results distributed for April 23 design review.
Cband conical load prototype tested with results equal to previous cold load.
Digital Group Status 14-APR-07 THRU 20-APR-07
***Operations, Problem Summary***
Spectrometer...
During a routine maintenance check of the Spectrometer, Nathan discovered some changes in zone temperatures and airflows. Further investigation uncovered a slow-running exhaust fan on top of the cabinet which could explain the increase in bad lags we dealt with a few weeks back. A spare fan was located; however, when the fan shroud was opened to allow replacement, the existing fan began operating normally and was left in place. These fans will now be checked daily for an indefinite period.
Active Surface Maintenance...
- One fuse was replaced to clear a patch of 64 actuators.
- One LVDT module was repaired to clear another patch of 16 actuators.
***Development***
Spectrometer LTA Re-design...
After many trials and tribulations in dealing with our old development system, I finally managed to produce a PROM which results in slower rise- and fall-times on the ADDER FPGAs' data busses. Testing revealed that the number of bad lags was reduced by at least a factor of 10; however, a very small number of bad lags do still show up. This will require further investigation and may stretch the project another week or so.
New Pulsar Backend...
The balance of required Xilinx chips was received in and shipped to Digicom for use in producing our IBOB's. No other news to report.
PTCS...
An attempt was made to reprogram all three GDAQs (serving three accelerometers and the Quadrant Detector) in order to improve timestamp precision and message handling. During deployment, a previously undetected drift in timestamp offsets between the GDAQs and their host was observed, so the original firmware was reinstated for a pointing run scheduled for Thursday night. The plan is to debug the new firmware and re-reprogram the GDAQs during maintenance next week.
ALMA...
On-going efforts are continuing fairly smoothly on the ALMA front.
***Plans***
- Begin weekly check of Spectrometer exhaust fans...
- Continue testing the first three LTA FPGA Adapter PCBAs...
- Re-reprogram the GDAQs to improve timestamp precision and message handling...
- Continue ALMA efforts as required...
Randy
Tim will be filling in this new section weekly.
Tachometers continue to be a problem. We plan to send some out for repair.
Work continues on developing the servo interlock upgrade to be installed this summer. Work on developing logic replacing the large board is underway. A design review is being planned for May sometime.
We are in week three of the third development cycle of 2007 which can be viewed at PlanOfRecordC32007. We are scheduled for release on 16 May 2007.
Operational and user support was relatively light this week and included:
- Investigated several operator's log reports of failure to send pointing corrections.
- Participated in recovery after power failure.
- Responded to report that GFM couldn't plot spectral line scans; determined it was a symptom of cabling file update and reloaded cabling file in IF Manager.
Modification Requests:
- MRs ready for integration/regression testing:
- MRs ready for sponsor testing:
- MRs under development:
- 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:
- MRs under sponsor review:
- Update Pointing/Focus code to Handle Old Data Sets (ModificationRequest3C207)
- MR written, with sponsor for review. Developing unit tests.
- MRs being written:
- Other Activities:
- Dynamic Scheduling - We are in the process of responding to comments received on the Overview. Melinda and Mark are completing work on Criteria II of Selection Rules and have 54 unit tests in place. They are placing Dana's required weather data into a database and have started implementing Criteria III.
- Analysis of Trajectory Generation Problems - Currently working on increasing the rate of commands generated in the antenna in an effort to use signal processing to wipe out the glitches.
- 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. Bob has been evaluating relevant technologies. He has been experimenting with two ways to possibly allow "IDL" to interact with Python - gdl (the gnu IDL) and pyIDL. pyIDL is very promising and Bob says that it works as advertised; he was able to involve GBTIDL from Python and found the process to be straightforward.
PTCS -- PTCS Team
- Astronomy
- Last night we spent 6 hours performing a slow 360deg azimuth scan (back and forth) in order to get a complete track map. This will be useful for two reasons:
- Kim will use it determine if the recent pointing data is well-fit by the new pointing model (under development) which has additional terms for local tilt and alidade twist induced by track irregularities.
- It will provide a before & after comparison of the deteriorating track vs. the new track.
- Kim is analyzing the recent pointing data and is noting some mysteries.
- When attempting to fit the forward/backward scan hysteresis with an encoder wind-up term (of order 1 arcsec), the newest pointing data shows an opposite (unphysical) sign compared to all of the old data. Ron has added a feature to prepoint to compute and output the average az/el encoder velocities during a scan to ensure that a forward scan is really a forward scan. This test was passed, so the ball is back in Kim's court on this. In any case, it will now be easier to check if there is a rate dependence in this term.
- Using the recent pointing data (taken since 2006/08/17) the focus model parameters -- although mostly unchanged -- are showing a much higher statistical uncertainty than before (a factor of 3.5 in standard deviation!). Seems like this must be a math error somewhere rather than a physical change...
- Fred has added the intentionally built-in panel errors to his surface simulation. Although small compared to actuator and panel setting errors, the effect of these errors on the beam pattern had never previously been modelled in a two-dimensional sense since the construction of the telescope. We thought that they might explain some of the difference between the az and el Moon scans. We are hopefully approaching a final version of the Moon scan fits, though the 2007 scans still need to be properly calibrated.
- Engineering
Not much to report. Ryan and I tested the 8-bit spigot calibration last Friday and found that our "fixes" only fixed part of the problem. We've both been swamped this week and so have had very little chance to work on it. Hopefully next week will be better. It would be really great to fix the problem so that we can test the 8-bit modes on a real pulsar before the telescope gets stowed to track repairs....
MIT/LL 43m Project -- Glen
Almost normal spacecraft tracking, except for problems due to power outage.
Due to some log processing on "Lodestar", a solaris machine, the automatic
file generation did not run for two days. A reboot of Lodestar fixed the
problem. All required files were created.
Normal spacecraft tracking next week.
We have begun the memo summarizing the results from our Ka-band calibration algorithm and commissioning.
-- CarlBignell - 19 Apr 2007
Revision r1.10 - 20 Apr 2007 - 12:57 GMT - JohnFord
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