GBT Operations & Commissioning Meeting
AGENDA
Activities List
-
- We did receive the final shipment of wear plates this week, and also a package of shim material. This means that all components and material are here on site.
- Preparations continue for the outage. John Shelton has been laying a benchmark, and the mechanics have continued modifications to the lower loading platform. Bob Goldizen is completing power stations as well.
We supported 17 projects in 32 observing sessions, including 3 VLB sessions. The telescope was also scheduled for 8.5 hrs of maintenance, 7 hrs of PTCS pointing tests, and 3.8 hrs of Ka-band commissioning (see below for results). Lost time was 9.7 hrs, about 6.1% of the time scheduled for observing and tests. The causes of lost time were myriad:
- Observer Errors (none)
- Weather (1.0 hrs, 0.6%)
- Winds (2 instances) : 0.5 hrs
- Snow (2 instances) : 0.5 hrs
- Software/Hardware/Operational (8.7 hrs, 5.5%)
- Elevation motor : 3.1 hrs
- Astrid (5 instances) : 2.0 hrs
- Az Motor/Brakes/Controller (3 instances) : 0.9 hrs
- MArk V VLBI Power Supply : 0.8 hrs
- Spectral Processor (9 instances) : 0.7 hrs
- Source Not up : 0.6 hrs
- Active Surface : 0.4 hrs
- MCB Receiver reboot : 0.3 hrs
1.5 of the 2 hrs lost to Astrid were related to Spigot script problems that seem to arise from account privileges. Over the last few weeks, a number of hours have been lost to motor or servo problems. Is there some pattern to these problems? I didn't see in the logs a god explanation as to why the Spectral Processor was having such a tough time.
Last Week
=========
Observations for proposals
GBT06C-051, GBT07A-098, GBT07A-021,
GBT07A-089, GBT06B-032, GBT07A-100,
GBT06A-033, GBT07A-034, GBT06B-033,
GBT02A-054, GBT06C-056, GBT06C-003,
GBT06B-037, GBT06B-028, GBT06C-105,
GBT06B-018, BB231
Completed proposals
GBT06B-032, GBT06B-033, GBT02A-054,
GBT06B-028
Next Week
=========
Observations scheduled for **
GBT07A-041 [ P ] Antonio Crapsi
The temperature structure in the Vello prototype
L1014
GBT07A-042 [ P ] Andrea Tarchi
H2O versus continuum in the nucleus of the
megamaser galaxy 3C403
GBT07A-031 [ P ] Jim Braatz
The Megamaser Cosmology Project: Accelerations in
Maser Disks
GBT06C-051 [ P ] Lincoln Greenhill
Monitoring 2 NGC4258-like Masers: Measurement of
Distances / Constraint of LCDM
GBT07A-098 [FPB] Fernando Camilo
Studying the magnetar XTE J1810-197
GBT07A-021 [F ] Arthur Wolfe
Detection of B Fields in Damped Lyman-alpha Sytems
GBT07A-034 [ P ] Jim Braatz
The Megamaser Cosmology Project: A Survey for H2O
Masers in SDSS and 2MRS AGNs
GBT07A-100 [ P ] Pat Thaddeus
Search for the anions C4H- and C8H- in TMC-1 and
additional observations of C6H-
GBT06A-033 [ P ] Howard Bond
Search for SiO Masers in Eruptive Variable Stars
Similar to V838 Monocerotis
GBT06B-044 [F B] Robert Ferdman
Timing Binary and Millisecond Pulsars from the
Parkes Multibeam Survey
GBT07A-037 [ B] Karen O'Neil
Further Observations of HI in Galaxies and
Environments
GBT06C-045 [ B] David Champion
A Search for Radio Emission from Magnetars after
Outburst
GBT06C-056 [ PB] Pat Thaddeus
Search for the Five-Membered Aromatic
Heterocyclic Ring Pyrrole (c-C4H5N)
GBT07A-016 [ B] Jennifer Donovan
How "Dry" Are Dry Mergers?
GBT06C-003 [ P ] Tony Remijan
Additional Transitions of Interstellar Methyl
Isocyanate (CH3NCO)
GBT06C-048 [F ] Nissim Kanekar
HI 21cm absorption in strong MgII and CI
absorbers in the redshift desert
GBT06C-105 [ P ] Jeff Wagg
A confirmation of strong CO J=1-0 emission at
z=5.2
GBT06B-018 [ B] Michael Kramer
Timing and General Relativity in the Double
Pulsar System
** Scheduled as F-ixed, P-rimary, B-ackup
Contact Information for 04/26/2007 - 05/10/2007
=======================================
Proposal PI Bands Email [NRAO contact]
---------- ------------------ ----- --------------------
GBT07A-041 Antonio Crapsi K crapsi@strw.leidenuniv.nl [Jim Braatz]
GBT07A-053 Dunc Lorimer 3 Duncan.Lorimer@mail.wvu.edu [Toney Minter]
GBT07A-098 Fernando Camilo S fernando@astro.columbia.edu [Scott Ransom]
GBT06A-054 Paul Demorest L demorest@astron.berkeley.edu [Scott Ransom]
GBT07A-100 Pat Thaddeus K pthaddeus@cfa.harvard.edu [Frank Ghigo]
GBT07A-034 Jim Braatz K jbraatz@nrao.edu [Jim Braatz]
GBT07A-023 G. Welch L gwelch@orion.stmarys.ca [Toney Minter]
GBT07A-101 Clive Dickinson B cdickins@astro.caltech.edu [Brian Mason]
GBT07A-058 Jane Greaves 3 jsg5@st-andrews.ac.uk [Glen Langston]
GBT07A-037 Karen O'Neil L koneil@nrao.edu [Karen O'Neil]
GBT07A-016 Jennifer Donovan L jen@astro.columbia.edu [Frank Ghigo]
GBT07A-038 Jane Greaves B jsg5@st-andrews.ac.uk [Larry Morgan]
GBT06B-015 Larry Morgan K lmorgan@nrao.edu [Larry Morgan]
GBT06C-003 Tony Remijan K aremijan@nrao.edu [Larry Morgan]
GBT06C-105 Jeff Wagg K jwagg@nrao.edu [Ron Maddalena]
BB231 Jim Braatz K jbraatz@nrao.edu []
Scheduled hours [backup]
========================
Category/Month-> April
Astronomy ~ 621 [254]
Maintenance ~ 53 [017]
Test & Comm ~ 41 [009]
Un-assigned ~ 5
Proposal Checkouts #[hrs]*
=========================
Awaiting checkout - 0[0]
Active checkout - 0[0]
On Hold - 14[358]
Schedule - 74[1747]
Completed - 450[6244]
* All but completed queue applies to GBT only proposals
Current backlog [hours prior to 07A*] = 1061
[2003:3(1), 2004:73(9), 2005:405(16), 2006:575(35), 2007:5(1)]
Backlog includes 78 hrs of monitoring projects
187 hrs of vlbi projects
Total time to discharge [hours] = 5532
Includes 148 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
Several people on vacation this week.
New, expanded range power samplers have been installed in all sixteen of the
1-8 GHz Converter Modules. A production schedule was made back in December showing completion on 20 April, so the work was finished one week early.
The first C-band multichip module containing the room-temperature RF/IF
components has now been tested and the performance is quite good. A Technical Seminar / design review is being organized for the week of April 23.
A stability problem was reported in IF channel 6, and testing isolated it to the IF Rack, before the fiber modulator. In the limited maintenance time available, the performance was improved by replacing the ODM, but there still are occasional glitches so the module is still in the bad device file.
It is our understanding that none of the Gregorian receivers will be needed this summer May 1 - Aug 1, and so routine maintenance (e.g. cryogenics) can be done at any time of our choosing.
Digital Group Status 07-APR-07 THRU 13-APR-07
***Operations, Problem Summary***
FranK? Ghigo reported a problem with a power supply in the Mark-5 VLBI unit. Measurements confirmed that the +5Vdc supply was running at +4.6 volts, which is clearly out of spec. A new power supply was received from Socorro and was swapped out by Nathan. The unit now appears to be functioning properly.
Active Surface Maintenance...
No work was done on the active surface this week.
***Development***
Spectrometer LTA Re-design...
Three of the new LTA FPGA Adapter boards have now been completed and are currently undergoing testing and evaluation. With the new boards in place, there is clear evidence of ground bounce (as before), which results in bad lags under longer integrations. Next week, I plan to consult with Ray Escoffier in an effort to modify the personalities of the ADDER FPGAs, slowing down their I/O rise- and fall-times. This is expected to eliminate the ground bounce problems; but will require further in-depth testing which will push the project out another week or so.
New Pulsar Backend...
John Ford now has our development workstation up and running here at GB with a VNC server which allows the UC Team to log in and continue their development efforts remotely. This setup seems to be working well and significant progress is now being made toward completion of our first-cut, simplified spectrometer.
ALMA...
On-going efforts are continuing fairly smoothly on the ALMA front.
***Plans***
- Continue testing the first three LTA FPGA Adapter PCBAs...
- Continue development efforts on New Pulsar Backend...
- Continue ALMA efforts as required...
Randy
We are in week two 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 up a little this week and last and included:
- Investigated report of reverse toggling of Astrid "halt" button, known problem.
- Provided config_tool operational support related to converter module issues.
- Investigated report of missing Antenna FITS files - antenna not in Scan Coordinator.
- Investigated report of stuck observation management run queue. We manually removed single entry to fix problem; cause unknown.
- Responded to Spectral Processor timing and data dump issues; restarted M&C processes (twice).
- Called regarding MCB problems with receivers; we had the operator reset MCB cards via rx-room reset box & restarted managers.
- Investigated operator's report of two sessions of GFM which showed different plots for same pointing data.
- Fixed spigot "hang" issues which were caused when monctrl public ssh key was overridden inadvertently.
- Provided user support for a bug in GBTIDL's nsave value.
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 being written:
- Fix Inclinometer Data Collection Problems (ModificationRequest1C207)
- Added capability to run pairs of inclinometers at different rates.
- Fix Accelerometer Timestamping/Data Collection (ModificationRequest2C307)
- Port Holography Manager to Linux (ModificationRequest1C307)
- Create Pyrgeometer Manager (ModificationRequest2C207)
- Update Pointing/Focus code to Handle Old Data Sets (ModificationRequest3C207)
- Testing candidate solution against multiple older datasets while completing MR writeup. This is a modification affecting all of GFM, not just for Pointing/Focus code.
- Modify Peak Finding Algorithm for Pointing/Focus Code (ModificationRequest4C207)
- Conducting a comparison of peak finding results between old and new algorithms, across many datasets, to make sure new algorithm performs at least as well as old one while completing MR writeup.
- Other Activities:
- Dynamic Scheduling - We are in the process of responding to comments received on the Overview. Melinda and Mark are now working on the second requirement, Criteria II of Selection Rules.
- 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. Bob has been out a lot lately due to uncontrollable circumstances, so progress has been slow.
- Evaluate GBT Data Handling Status & Future Options - In progress. Bob has been out a lot lately due to uncontrollable circumstances, so progress has been slow.
No computing issues affecting observing.
PTCS -- PTCS Team
- We had a successful observing run on Monday night. We first did 1.5 hours of 18 GHz observations at the half-power point of the beam: some scans were taken with the offset applied in azimuth, and some in elevation. This was to validate the dynamical model being used to fit (and remove) the large structural vibrations often seen in the inclinometer datastream during normal observations. The vibration signal at the inclinometer is compared to oscillations seen in the azimuth encoder datastream (as a reality check). A few significant "events" were seen in the inclinometers which appeared to correlate with large excursions in the receiver total power output. Kim is analyzing the results. We also obtained 4.5 hours of 9 GHz all-sky pointing. We now have collected about 12 hours of X-band all-sky pointing data since the improvements were made to the inclinometer data acquisition and time-tagging software. This may be enough data to eventually fit a model that includes the new terms for alidade distortion caused by local track effects. To support this effort, we now plan to do a full track map at slow rates before the April 30th shutdown. This is a prelude to the process we will follow after the track replacement.
- A PTCS project note (#56) describing Savitsky-Golay filtering has been released by Kim. This technique is being used to estimate the azimuth and elevation encoder rates and accelerations by using the regularly-sampled time series of angle measurements recorded by the logger.
- Work continues on fitting the recent Q-band Moon scans with a combination of surface actuator and panel misalignment errors. A PTCS project note describing the results will be initiated soon. It will include simulations of the effect of pointing errors (of various magnitudes) on holography maps.
- Significant time was spent helping to write the science case for the 3mm dual-beam receiver and for the 3mm focal plane array receiver.
While I was travelling the past couple weeks, Ryan thinks that he might have figured out the problem with the 8-bit Spigot calibration. We'll be testing this during the commissioning meeting.
For the new pulsar backend, Joeri van Leeuwen, Dan Werthimer and I did some calculations after several other pulsar people saw our plans to use the iBob+BEE2 for coherent dedispersion (sans a computer cluster). Bottom line is that all still looks OK for this, although we might need a BEE2 for each poln if we are doing a full 1GHz. One of the big worries was that we would need to use very large FFTs which are hard on an FPGA. Turns out that we don't need to do this, though, and can get by with tons of ~16K transforms. Obviously there is a lot more work to do on this...
MIT/LL 43m Project -- Glen
- Week of successful spacecraft tracking.
- High priority track on Wednesday ran without a hitch (so far as we know).
We're done!! We finally have a firm Ka-band detection of C0(1-0) at a redshift of 2.3. The data came from a 4hr run in January and another ~4hr run last weekend. Jeff Wagg graciously gave up time from his own project in order for us to get this last run. On both days, the weather was not the greatest (5-6 mm of precipitable water and, for last weekend, snow flurries). Both times we used the jury-rigged technique of subreflector nodding and the calibration philosophy that Charlie Figura helped worked out. After calibration, first order baselines over a fair part of 800 MHz was all that was needed. DJ is working on a more proper calibration algorithm that might improve baselines further. The measured rms noise was 0.5 mK, exactly the theoretical value.
The source we observed is from project 5A29 (Vanden Bout, Solomon & Maddalena) where it was predicted that the line would have a peak flux of 1.6 mJy. We're getting 1.7 mJy with an approximate error of 20%. (The algorithm DJ is working on should do better.) The line center and width are within 1 sigma of the values given in Solomon & Vanden Bout's Annual Review article.
A few items remain on the to-do list: We'll be writing a memo summarizing our results. We'll need to incorporate subreflector nodding into Astrid. Above 35 GHz, and especially 36 GHz, Tsys are too high for practical observing. Even below 35 GHz, Tsys has a periodic frequency structure where Tsys can vary by about 50% in a few hundred MHz. Luckily, the last problem does not introduce baseline structures with our calibration scheme but it does produce noise levels that very obviously change across an 800 MHz band.
There are a good number of folks who contributed to this success. In particular, over the last four months, the dedicated work of Charlie, DJ, and Jeff.
-- RichardPrestage - 12 Apr 2007
Revision r1.13 - 13 Apr 2007 - 14:16 GMT - AmyShelton
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