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GCN Circular 24724

Subject
LIGO/Virgo S190602aq: Upper limits from Fermi-GBM Observations
Date
2019-06-03T00:35:20Z (5 years ago)
From
Colleen A. Wilson at NASA/MSFC/NSSTC <colleen.wilson@nasa.gov>
C.A. Wilson-Hodge and C. M. Hui (NASA/MSFC) report on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo group

For S190602aq and using the initial bayestar.fits skymap, Fermi-GBM was observing 67.3% of the localization probability at event time. 

There was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo/ detection of GW trigger S190602aq (GCN 24717Not found
 
 
). An automated, blind search for short gamma-ray bursts below the onboard triggering threshold in Fermi-GBM also identified no counterpart candidates. The GBM targeted search, the most sensitive, coherent search for GRB-like signals, was run from +/-30 s around merger time, and also identified no counterpart candidates.

Part of the LVC localization region is behind the Earth for Fermi, located at RA = 148.4 and Dec = -10.9 with a radius of 67.5 degrees.
We therefore set upper limits on impulsive gamma-ray emission. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395Not found
 
 
, we set the following 3 sigma flux upper limits over 10-1000 keV (in units of 10^-7 erg/s/cm^2):

Timescale ��Soft     Normal ����Hard
------------------------------------
0.1 s: ��������      4.3       7.5         17.0 
1.0 s: ��������      1.1       3.4          8.2
10 ��s:   ����      0.27      0.63         1.7 

Assuming the median luminosity distance of 797 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^49 erg/s):
Timescale ��Soft     Normal ����Hard
------------------------------------
0.1 s: ��������5.0 ������������������8.0         30.0 ������
1.0 s: ��������1.3 ������������������3.6         14.5 ������
10 ��s:   ����0.3          0.7          3.0��