  We present results from AstroSat observation of the recent outburst of GRO
J2058+42, an X-ray pulsar in a Be-binary system. The source was observed on
April 10, 2019 by LAXPC and SXT instruments on AstroSat during its declining
phase of the latest giant outburst. Light curves showed a strong pulsation of
the 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 in
light curves between 3--80 keV energy band with increase in intensity by up to
1.8 times its average intensity. Pulse profiles obtained between 3--80 keV
energy band of the pulsar showed strong dependence on energy. A broad peak was
observed in the power density spectrum of the source consistently during
AstroSat observations with its peak oscillation frequency of 0.090 Hz along
with its higher harmonics, which may be due to quasi-periodic oscillations, a
commonly observed phenomenon in transient X-ray pulsars, during their outburst.
AstroSat observation also detected cyclotron absorption features in its
spectrum 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 dependent
variation in its energy and relative strength of these features. The spectrum
was well fitted with an absorbed black-body, a Fermi Dirac cut-off model and
alternatively with an absorbed CompTT model. Both these models were combined
with a Fe-line and three Gaussian absorption lines to account for observed
cyclotron resonance scattering features in the spectrum.
