VEGAS Pulsar Project Meeting: 2015 March 16th 2:00 - 3:00pm ET

Room / Connection Details

  • GB-137 / Soc 280
  • 434-817-6443

Housekeeping Details

  • Main wiki page
  • gbsapp Mailing List
  • Location and regular date and time of meeting - agreed weekly on Mondays; GB-137 / Soc-280; 2-3pm ET
  • ETK codes:
    • Electronics: 432510.GB3015
    • Software: 893252.GB3015
    • Science: 432540.GB3015

Resource Allocations


  • Some of the electronics group intern Arindam Sengupta, to share tasks with Randy and Jason.


  • Ryan, Sam, Arindam, Jason, Ray, Justin, Paul, Melinda, Marty


General Updates

  • New BOF files
    • Jason put together a page with a summary of all BOF files (progress, naming conventions, etc.)
      • Note that columns can be sorted by clicking on the headings
      • Jason will add columns for priority and status
      • We will link to wiki pages detailing the specific tests of each mode in the status column as they become available
    • Randy and Arindam are working on testing in Xilinx v14.6 before making the jump to v14.7
    • Bug identified in fft block
    • Will add switching signal and snap blocks so they can be read by VEGAS
  • Config tool: VEGAS pulsar specific keywords and dual GUPPI/VEGAS modes
    • No updates
    • Richard and Ryan will review plan to make sure there are no outstanding questions or information that needs to be passed on
  • Manager
    • Mode parameter is now a string in the agreed upon format
    • Ryan and Justin will meet to go discuss how various parameters are used
  • C-Band tests
    • Idea is to use existing BOFs to capture 4 GHz of bandwidth
      • There are some science cases this would be useful for, like globular cluster and Galactic center searches, high frequency magnetar observations
      • Would also be a great advertisement for the GBT, since no other telescopes can currently do this for pulsar observing
    • Karen was reluctant to advertise new capabilities until we are really ready to support them
    • Would need to get GBT metadata to populate PSRFITS files
      • Not currently supported via dealer/player but Ray doesn't think this would be too difficult
    • We decided to get an estimate from Justin on when the Manager will be ready. If it is on a very long timescale (~6 months) we may push ahead on this using friendly scripts to run dealer/player. If it is on a short timescale (~weeks) we may just wait. If it is in between, we will reevaluate.


  • Timeline: Do we need to reevaluate in light of ongoing work with spectral line modes?
    • Joe and Randy had to focus on spectral line modes and may have slide by ~1 month but are working on pulsar modes now
    • Don't foresee any major adjustments to timeline
  • TOA periodicities in DIBAS BOF files
    • New tests
      • Analyze old data from early DIBAS testing to see if the problem occurred then
      • Look for periodicities on longer timescales in 8-hr scans
      • Test coherent modes
      • Test with a drastically different AP frequency
      • Jason will double check that Valon is locked to external source and will double check 10 MHz reference and 1 PPS
      • Randy will check to make sure player is configuring correctly
      • More advanced tests could include hooking AP to GUPPI to definitively rule it out and running with VEGAS hardware to make sure it isn't something specific to SRBS

TOA periodicities from DIBAS BOF files

  • Ryan thinks the controlling factor is scan length
    • Other factors like number of channels, bandwidth, etc. do not seem to have an impact
  • Ryan tried several different scan lengths from 30 s to 420 s, recorded strongest periodic signal via periodogram analysis
    • Periodicities are on longer timescales than individual scan but are not consistent multiples of a scan length
    • General trend towards longer periods for longer scan lengths, but not other obvious patterns
  • What are the next steps? What other tests would be useful for troubleshooting?
  • Residuals and periodogram plots from all start/stop tests.: toa_periodicities_plots.tar

toa periodicities summary.png

Date / Time of Next Meeting

  • Tentatively agreed to meet in one week (March 23), but will reevaluate based on results of the next set of tests

-- RyanLynch - 2015-03-16
Topic attachments
I Attachment Action Size Date Who Comment
toa_periodicities_plots.tartar toa_periodicities_plots.tar manage 4 MB 2015-03-16 - 09:24 RyanLynch Residuals and periodogram plots from all start/stop tests.
toa_periodicities_summary.pngpng toa_periodicities_summary.png manage 126 K 2015-03-16 - 09:22 RyanLynch Summary of periodicities seen start/stop tests using DIBAS BOF
Topic revision: r2 - 2015-03-16, RyanLynch
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