{
  "subject": "LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations",
  "submittedHow": "web",
  "body": "\nV. Sharma (NASA GSFC/UMBC) reports on behalf of the Fermi-GBM Team:\n\nFor S240629by (GCN 36784) and using the initial bayestar skymap, Fermi-GBM was observing 17.8% of the localization probability at event time.\n\nThere was no Fermi-GBM onboard trigger around the event time of the LIGO/Virgo/KAGRA (LVK) detection of GW trigger S240629by. 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.\n\nPart of the LVK localization region is behind the Earth for Fermi, located at an RA=30.0, Dec=-25.6 with a radius of 67.4 degrees. We therefore set upper limits on impulsive gamma-ray emission for the GW localization region visible to Fermi at merger time. Using the representative soft, normal, and hard GRB-like templates described in arXiv:1612.02395, we set the following 3 sigma flux upper limits over 10-1000 keV, weighted by GW localization probability (in units of 10^-7 erg/s/cm^2):\n\nTimescale Soft Normal Hard\n------------------------------------\n0.128 s:  2.1 \t 3.5 \t7.2\n1.024 s:  0.7 \t 1.1 \t2.1\n8.192 s:  0.3 \t 0.5 \t0.9\n\nAssuming the median luminosity distance of 1205 Mpc from the GW detection, we estimate the following intrinsic luminosity upper limits over the 1 keV-10 MeV energy range (in units of 10^50 erg/s):\n\nTimescale Soft  Normal Hard\n------------------------------------\n0.128s:  0.6\t0.8\t  2.9 \n1.024s:  0.2\t0.3\t  0.8 \n8.192s:  0.1\t0.1       0.4",
  "format": "text/plain",
  "bibcode": "2024GCN.36793....1S",
  "circularId": 36793,
  "createdOn": 1719713932945,
  "submitter": "Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>",
  "eventId": "LIGO/Virgo/KAGRA S240629by"
}