GCN Circular 21432

I. Bartos, S. Countryman (Columbia), C. Finley (U Stockholm), E. Blaufuss
(U Maryland), R. Corley, Z. Marka, S. Marka (Columbia) on behalf of the
IceCube Collaboration

We searched IceCube online track-like neutrino candidates (GFU) detected in
a [-500,500] second interval about the LIGO-Virgo trigger G296853. We
compared the candidate source directions of 4 temporally-coincident
neutrinos to the BAYESTAR skymap, with the following parameters:

#            dt[s]     RA[deg]    Dec[deg]      E[TeV]  Sigma[deg]
------------------------------------------------------------------
1.         -310.02        65.9        -5.2        1.11         0.5
2.         -128.45        74.0       -29.2       52.68         0.2
3.          361.60       164.0       -14.6       20.50         0.5
4.          438.49       121.1       -64.8       81.83         2.1


(dt--time from GW in [seconds]; RA/Dec--sky location in [degrees];
E--reconstructed secondary muon energy in [TeV]; Sigma--uncertainty of
direction reconstruction in [degrees])

The analysis found NO COINCIDENT ONLINE TRACK-LIKE NEUTRINO CANDIDATES
detected by IceCube within the 500 second window surrounding G296853 within
the BAYESTAR skymap.

A coincident neutrino-GW skymap has been posted to GraceDB (<
https://gracedb.ligo.org/apiweb/events/G296853/files/
coinc_skymap_initial_icecube.png,0>). A JSON-formatted list of the above
neutrinos can be downloaded from GraceDB at: <https://gracedb.ligo.org/
apiweb/events/G296853/files/IceCubeNeutrinoList.json,0>

In addition, we are performing coincident searches with other IceCube data
streams, including the high-energy starting events (HESE) and Supernova
triggers.  HESE events have typical energies > 60 TeV and start inside the
detector volume, leading to a relatively pure event sample with a high
fraction of astrophysical neutrinos.  The SN trigger system is sensitive to
sudden increases in photomultiplier counts across the detector, which could
indicate a burst of MeV neutrinos.  We will submit separate GCN circulars
if coincident HESE or SN triggers are found.

The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector
operating at the geographic South Pole, Antarctica.  For a description of
the IceCube realtime alert system, please refer to <
http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1610.01814
Not found
 
 
>; for more
information on joint neutrino and gravitational wave searches, please refer
to <http://adsabs.harvard.edu/cgi-bin/bib_query?arXiv:1602.05411
Not found
 
 
>.