X-ray pulsar A 0535+262 reached ~3 Crab: update with Neil Gehrels Swift Observatory

ATel #14170; Sabyasachi Pal (MCC/ICSP) and Manoj Mandal (MCC)
on 12 Nov 2020; 22:11 UT
Credential Certification: Sabyasachi Pal (sabya.pal@gmail.com)

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Earlier we reported the Swift/BAT detection of renewed activity in the X-ray pulsar A 0535+262 (ATel #14157). Since the source was in the rising phase and the flux was increased to ~755 mCrab on UTC 6th November 2020 (MJD 59159), we proposed Swift ToO monitoring observation to find the state of the source. On UTC 12th November 2020 (MJD 59165) the BAT flux rose to a value 0.61±0.02 cts/cm²/sec (~2.9 Crab), which is maximum in last 10 years and closely match giant outburst of the source in 2010 (Atel #2324, #2336). The flux of the source is still rising.

A ~3 ks Swift/XRT observation in the photon counting mode was performed on MJD 59161.31 (UTC November 9, 2020). The spectrum was fitted using XSPEC with model phabs*(powerlaw+bbody). The flux for A 0535+262 was found to be 7.2 × 10^-8 erg cm^-2 s^-1 in the 1-10 keV energy band. The spectral fit estimates a photon index of 4.4±0.2 and neutral hydrogen column density 1.9±0.12 × 10²² cm^-2. Further analysis is ongoing.

The source was clearly detected with the ~3ks UVOT observation on MJD 59161.31 with a uvm2 filter (Vega) magnitude of 10.79±1.09 (stat)±0.03 (sys).

We thank the duty scientists of the Neil Gehrels Swift Observatory for the extremely rapid and efficient scheduling of the observation.