{
  "format": "text/plain",
  "submitter": "Lorenzo Scotton at UAH <lscottongcn@outlook.com>",
  "createdOn": 1732578803892,
  "subject": "LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations",
  "circularId": 38316,
  "bibcode": "2024GCN.38316....1S",
  "body": "L. Scotton (UAH) reports on behalf of the Fermi-GBM Team:\n\nFor LIGO/Virgo/Kagra (LVK) S241125n (GCN 38305) and the Swift/BAT-GUANO candidate counterpart (Tohuvavohu, A. et al. 2024, GCN 38308), we used the LVK/BAT combined skymap (combined-ext.multiorder.fits,2; LVK and Swift/BAT, GCN 38315). Fermi-GBM was observing 97.1% of the localization probability at event time.\n\nThere was no Fermi-GBM onboard trigger around the event time of the LVK detection of GW trigger S241125n. 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-BAT localization region is behind the Earth for Fermi, located at an RA=335.8, Dec=12.1 with a radius of 67.7 degrees. We therefore set upper limits on impulsive gamma-ray emission for the LVK-BAT 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:   1.7      2.9        5.5 \n1.024 s:   0.6      1.0        1.7 \n8.192 s:   0.2      0.3        0.6 \n\nAssuming the median luminosity distance of 3213.8 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:    3.3      4.9      15.8\n1.024s:    1.3      1.6       4.9\n8.192s:    0.4      0.5       1.6",
  "submittedHow": "web",
  "eventId": "LIGO/Virgo/KAGRA S241125n"
}