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Review Committee Meeting Monday 13 March 2006 09:00 PST / 12:00 EST

Minutes: Monday 13 March 2006 09:00 PST / 12:00 EST

Agenda and Contact Info


  1. Go over technical documentation for the SGR 1806-20 Hyperflare Search [ PDF ]

Contact Info

AccuConference teleconferencing service:
   Phone: 1-800-704-9896, participant code: 038621#
   International callers ++1-404-920-6472 with same code


  1. Announcements
    • Draft presentations are now being made available. We need to look at them off line.
    • An updated (now complete) draft of Soumya's documentation is now available.
  2. Luca described a broad overview of the SGR 1806-20 hyperflare and the search for gravitational waves associated with it.
    • At time of event, only H1 was in lock. It was at the beginning of a locked interval.
    • Central idea: QPOs are observed. Use these to identify frequencies and time periods to look for GWs.
    • Method: compute rms value of h for data band-passed to the frequency of the QPO. Off-source is at later times (after the QPO has disappeared). Need to do different integration times (different satellites observed QPOs for different durations) and different bandwidths (frequency drift of QPO).
    • "Closed box": the on-source data has been replaced by random numbers. Upper limit is the strength of injections required to exceed on-source value 90% of the time.
    • E.g., Fig 9 on Page 29 of document. Note: green line is the on-source result but with the real data replaced by random noise. Note that it is somewhat high. It tends to be high in several other similar plots ... probably because the same random number seed was used.
    • Repeat with different seeds to make sure that there isn't any bias in the search.
    • Another way to estimate sensitivity is to use the median value rather than a value drawn by random data. This would be easier to explain.
    • Time from 0s after burst and 170s (when QPO starts to be observed) is considered part of the "background". This should not be part of the background.
    • What abound looking at nearby frequency bands? This is already done in a sense: when the on-source band has a 4-sigma excursion at the same time as the off-source band has a 4-sigma excursion, that data is dropped from the background estimates. This gets rid of breathing.
    • Hypothetical source is a starquake on an isolated magnetar. Expect that toroidal modes are excited on the crust of the neutron star. These mechanical modes will prodcuce gravitational waves. Estimates of strength from the mass quadrupole formula. Would current quadrupole radiation be more important? Should check with Ben Owen.
    • 2nd order Butterworth filter used. Is this enough to suppress power outside of band (e.g., from 60 Hz)? Spectra have been produced showing the data after band pass filtering. These will be incorporated in document.
  3. AOB
    • Next week's meeting will be cancelled. We'll continue after the LSC meeting. Meanwhile we will work off-line to review the draft presentations.
    • Peter: S4 results now include a 6% constant calibration systematic. Is this correct?
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