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We have studied the timing and spectral properties of the BeXB 4U 1901+03during the 2019 outburst using \textit{NuSTAR}, \textit{Swift}, and\textit{NICER} observations. Flares are in all observations and were of tens tohundreds of seconds duration. Pulse profiles were changing significantly withtime and the luminosity of the source. An increase in the height of the peak ofthe pulse profiles was observed with energy. The pulse fraction increases withenergy and at the end of the outburst. The variation of the pulse profile withtime indicates the transition of the pulsar in different accretion regimes. Theabsorption like feature at 10 keV shows a positive correlation with theluminosity and along with other spectral parameters this feature was also pulsephase dependent. As the distance to the source is not precisely known hence wecannot confirm this feature to be CSRF and also cannot ignore other possibleexplanations of the feature. Another absorption like feature about 30 keV wasobserved in the spectra of the last two \textit{NuSTAR} observations and hasline energy of about 30.37$\pm$0.55 and 30.23$\pm$0.62 keV respectively. Wehave also studied the variation of the line energy, width, and optical depth ofthis feature with pulse phase. The softening of the spectrum along with theincrease in pulse fraction at the end of the outburst and absence of pulsationafter 58665.09 MJD suggest that pulsar has entered propeller phase, also abruptdecrease in \textit{Swift}-XRT flux supports the fact.

Timing and spectral properties of Be/Xray pulsar 4U 1901+03 during 2019 outburst