NICER monitored the emergence of U Sco in X-rays

ATel #15436; Marina Orio, INAF-Padova and U Wisconsin and Keith Gendreau, NASA-Goddard
on 15 Jun 2022; 20:31 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Marina Orio (orio@astro.wisc.edu)

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U Scorpii (ATels #15423, #15422, #15420, #15417) was monitored with NICER starting on 2022 June 8 at UT 18:19:20 in short (duration less than 1000 s) exposures over about 84 hours for a net exposure time of 11359 s. An X-ray source was detected with an average background subtracted count rate of 0.50±0.01 counts/s, with no large variations between exposures. We estimate an average absorbed flux of about 2 x 10^-13 erg/cm²/s in the 0.22-1.00 keV range and of about 2 x 10^-12 erg/cm²/s in the 0.22-10.00 keV range. The average spectrum can be approximately fitted with two components of thermal plasma with respective temperatures of 0.26 and 5.6 keV, but modeling is still in progress and we cannot rule out contribution of a power law component, or even the emergence of a blackbody-like component. NICER is a 0.2-12 keV X-ray detector operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA.