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S4 LIGO-GEO Burst Review Committee Meeting Tuesday 6 November 2007 12:00 Eastern

Minutes: Tuesday 6 November 2007 12:00 Eastern

Agenda and Contact Info


  1. Overview of LIGO-GEO analysis and paper
  2. WaveBurst+CorrPower pipeline
    • overview of codes used
    • status of code reviews
  3. coherent WaveBurst pipeline
    • overview of codes used
    • status of code reviews
  4. Discussion:
    • What needs to be reviewed?
    • Timeline
  5. A.O.B.

Contact Info

  InterCall telecon service:

    USA (toll-free): 1-866-616-1738
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    participant code: 251 288 9495#



Siong Heng, Sergei Klimenko, Keith Riles, Patrick Sutton (minutes), Keith Thorne, Igor Yakushin, Michele Zanolin.

Participants are referred to by the first letter of their last name.


  1. Overview of LIGO-GEO analysis and paper
    • First plot on summary page (tiff) is not visible in some browsers.
      Action item: Replace by png/gif/etc.
    • Discussion of old-vs-new waveburst:
      Z: How will the paper address the fact that the version of cWB used was not the "final" version?
      K: The analysis used v4.3.4, which has been reviewed. Post LIGO-GEO changes made the network configuration more flexible. There is no reason to believe the LIGO-GEO results from the older pipeline are incorrect. The newer version of the pipeline would probably give different (slightly better) results; however probably not significantly different. We can publish as-is (old version) results or re-run with the new version.
      Z: and K: not in favour of re-running.
      Z: would like to see a statement to the effect that the new version is also immune to the glitchiness of GEO.
      K: Originally intended no comparison of LIGO-GEO to LIGO-only since the LIGO-only S4 paper was not out. Possible conclusions: adding GEO to LIGO does not hurt sensitivity when using coherent methods, and can give better results than with incoherent methods; also, simple (non-) detection statement.
      Discussion to be continued off-line.
    • S: Were the same DQ flags applied for both pipelines?
      Y: Same segment lists were used.
      K: The DQ flags were applied after trigger production. There are some differences between way flags are applied in the two pipelines. Has to be checked (with Cadonati).
      Action item: Y will check segment lists for cWB, H will check lists of DQ flags for WP+CP (H will send pointer to elog entry).
    • Corrected MDCs:
      Cadonati is computing new effciencies for the WB-CP pipeline; Heng is working on the new cWB efficiencies. Numbers not available yet. Action item: Present new efficiency numbers (H).
    • Riles: Why is sensitivity ratio (hrss/S) different as a function of frequency for WB+CP and cWB? What would happen at, e.g., 500Hz?
      K: cWB imposes a threshold that SNR>36 in all three-detector sets. At lower frequencies GEO noise level limits WB+CP sensitivity more that that of cWB.
      K: There should be a document on analytic sensitivity estimates for WB+CP in S4.
      Action item: Klimenko will track down and circulate this document.
  2. WaveBurst+CorrPower pipeline: codes used and status of reviews
    • K: WB and CP codes used for LIGO-GEO were exactly same the versions as used for the S4 LIGO-only search. Both were fully reviewed for the LIGO-only search, and documentation is available from the S4 LIGO-only technical page.
      K: Old codes will need to be checked carefully for correct versions.
      R: The LIGO-only review probably did not look at sections of the codes specific to the 4-detector case.
    • K: cWB and WB both use wavelet analysis tool (wat) library, which contains all of the codes used in the analysis. The WB+CP search used v4.3.4; Y ran the jobs at CIT. Run using stand-alone library. All codes are stored in CVS (for review). Code available in CVS and as tarball. We keep track of different versions of libraries, and know which were used for S4-LG.
      Action item: Y will check on the tag version (if any) used for S4-LIGO-GEO.
    • H: Tech doc link points to correct, up-to-date version of tech doc of analysis.
      Action item: H will check it into DCC.
  3. coherent WaveBurst pipeline: codes used and status of reviews
    • Z: The version of cWB used in this paper has had review completed. Document written; needs to be "published" to burst group.
      Action item: Z will check that link to tech document on bulletin board is correct and that document is up-to-date.
  4. Discussion:
    • What needs to be reviewed?
      K: We need to recompute the efficiencies after correcting the sky position distribution.
      K: Post-production software includes separate codes for the 3 and 4 detector cases.
      R: The LIGO-only reviews did not inspect the 4 detector cases carefully.
    • Timeline:
      S: finish by March meeting.
      R: think possible to get done by Christmas, if no problems turn up with codes.
  5. A.O.B.
    • Action item: Sutton will circulate proposal for regular weekly telecons on Wednesdays at 10:00 eastern. Klimenko will miss next week, Riles will be late for this time, but otherwise looks okay.


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