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We present results from AstroSat observation of the recent outburst of GROJ2058+42, an X-ray pulsar in a Be-binary system. The source was observed onApril 10, 2019 by LAXPC and SXT instruments on AstroSat during its decliningphase of the latest giant outburst. Light curves showed a strong pulsation ofthe pulsar with a period of 194.2201 \pm 0.0016 s, and a spin-up rate of(1.65\pm0.06)\times10^{-11} Hz s^{-1}. Intermittent flaring was detected inlight curves between 3--80 keV energy band with increase in intensity by up to1.8 times its average intensity. Pulse profiles obtained between 3--80 keVenergy band of the pulsar showed strong dependence on energy. A broad peak wasobserved in the power density spectrum of the source consistently duringAstroSat observations with its peak oscillation frequency of 0.090 Hz alongwith its higher harmonics, which may be due to quasi-periodic oscillations, acommonly observed phenomenon in transient X-ray pulsars, during their outburst.AstroSat observation also detected cyclotron absorption features in itsspectrum corresponding to (9.7--14.4) keV, (19.3--23.8) keV and (37.8--43.1)keV. The pulse phase resolved spectroscopy of the source showed phase dependentvariation in its energy and relative strength of these features. The spectrumwas well fitted with an absorbed black-body, a Fermi Dirac cut-off model andalternatively with an absorbed CompTT model. Both these models were combinedwith a Fe-line and three Gaussian absorption lines to account for observedcyclotron resonance scattering features in the spectrum.

AstroSat observations of GRO J2058+42 during the 2019 outburst