Observations of the Crab Nebula with MACE (Major Atmospheric Cherenkov Experiment)

Abstract

The Major Atmospheric Cherenkov Experiment (MACE) is a large size (21 m) Imaging Atmospheric Cherenkov Telescope (IACT) installed at an altitude of 4270 m above sea level at Hanle, Ladakh in northern India. Here we report the detection of Very High Energy (VHE) $\gamma$-ray emission from Crab Nebula above 80 GeV. We analyzed $\sim$ 15 h of data collected at low zenith angle between November 2022 and February 2023. The energy spectrum is well described by a log-parabola function with a flux of $\sim (3.46\pm 0.26_{stat})\times 10^{-10}$ ${\mathrm{TeV}}^{-1}{\mathrm{cm}}^{-2}{s}^{-1}$, at 400 GeV with spectral index of $2.09\pm 0.06_{stat}$ and a curvature parameter of $0.08\pm 0.07_{stat}$. The $\gamma$-rays are detected in an energy range spanning from 80 GeV to $\sim$5 TeV. The energy resolution improves from $\sim$ 34% at an analysis energy threshold of 80 GeV to $\sim$ 21% above 1 TeV. The daily light curve and the spectral energy distribution obtained for the Crab Nebula is in agreement with previous measurements, considering statistical and systematic uncertainties.