Abstract:
A gamma-ray burst, named GRB 221009A, occurred on 9 October 2022 and
is the brightest ever observed GRB, whose frequency is now estimated as once in 10,000
years. This GRB was reported to be observed from many space missions, VLF receivers, and
ground observations in optical and radio data. Additionally, a strikingly large number of
very high energy (VHE) photons associated with this GRB were observed by the gamma-ray
and cosmic ray observatory LHAASO. Though gamma-rays of cosmic origin usually tend to
be absorbed by the atmosphere, the high fluence of this GRB, along with the observation
of more than 5000 VHE photons (0.5 to 18 TeV) by LHAASO from the ground, emphasises
the need to explore other possible ground observations of this GRB.
With RA = 288.3◦ and Dec = 19.8◦
, the exceptionally bright fluence of this GRB was
geographically centred on India. The present paper examines the effect of this GRB using
gamma-ray data in a low energy range (0.2–6) MeV obtained using NaI (Tl) detectors located
at Tirunelveli (Geographic coordinates: 8.71◦N, 77.76◦E), India. We report no significant
change in the observations associated with GRB 221009A. We discuss the extent of attenuation
of gamma-rays in the atmosphere that could explain the reported observations. Further,
we investigate the likelihood of ground observation of gamma-rays (< 10 MeV) for a much
more intense hypothetical GRB and estimate the parameters, such as distance, fluence, and
isotropic energy of such a GRB.
