arXiv:2103.00603v1 [astro-ph.GA] 28 Feb 2021 Multi-Wavelength Study of X-ray Pulsar 2S 1553-542 During Outburst in 2021 Manoj Mandal Midnapore City College, Kuturia, Bhadutala, West Bengal, India 721129 and Sabyasachi Pal Indian Centre for Space Physics, 43 Chalantika, Garia Station Road, Kolkata, India 700084 Midnapore City College, Kuturia, Bhadutala, West Bengal, India 721129 ABSTRACT We summarize the results of temporal and spectral analysis of the X-ray pulsar 2S 1553-542 using the Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift during the outburst in January-February 2021. During the outburst, the spin period of the neutron star was P =9.2822 ± 0.0001 s based on NuSTAR data. The temporal evolution of the spin period, pulse profile, and pulse fraction is studied during the outburst. The spectra of the source are studied for different days of the outburst and can be well described by a model consisting of – a black body emission or a power law. We have investigated the inter-day evolution of different timing and spectral parameters during the outburst. The energy dependence of the pulse profile was studied to investigate the evolution of the individual peaks and emission geometry of the pulsar with a different energy. The pulse profile of the source shows strong single peak nature with a hump- like feature of relatively lower intensity and it evolves significantly with different energy ranges. The evolution of the pulse profile is studied during different phases of the outburst and the pulse fraction shows a positive correlation with energy. Subject headings: accretion, accretion discs - stars: emission-line, pulsar: indi- vidual: 2S 1553-542. 1. Introduction The X-ray transient 2S 1553-542 was discovered using Small Astronomy Satellite 3 (SAS-3) in 1975 (Apparao et al. 1978) during the Galactic plane survey. A strong pulsation