{
  "createdOn": 1685411730730,
  "body": "S. Lesage (UAH) reports on behalf of the Fermi-GBM Team and the GBM-LIGO/Virgo/KAGRA group\n\nFor S230529ay (GCN 33889 and GCN 33891) and using the Bilby skymap, Fermi-GBM was observing 60.7% 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 S230529ay. 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=31.5, Dec=23.9 with a radius of 67.6 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:     1.2       1.9       3.5\n1.024 s:     0.5       0.7       1.2\n8.192 s:     0.2       0.2       0.4\n\nAssuming the median luminosity distance of 200.6 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:    0.009     0.013     0.039\n1.024s:    0.003     0.005     0.013\n8.192s:    0.001     0.002     0.005",
  "circularId": 33892,
  "subject": "LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations",
  "submitter": "Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>",
  "eventId": "LIGO/Virgo/KAGRA S230529ay",
  "bibcode": "2023GCN.33892....1L"
}