X-ray outburst of a radio-loud quasar

ATel #17159; M. Orio (University of Wisconsin and INAF-Padova), E. Behar (Technion), N. Nagashima (Chuo U.), K. Fukushima, Y. Kanemaru, S. Ogawa (JAXA), M. Audard (U. de Geneve), S. Inoue (Kyoto U.), Y. Ishihara (Chuo U.), T. Kohmura (TUS), Y. Maeda (JAXA), M. Mizumoto (UTEF), M. Nobukawa (NUE), K. Pottschmidt (UMBC, NASA GSFC, CRESST), M. Shidatsu (Ehime U.), H. Sugai (Chuo U.), Y. Terada (Saitama U.), Y. Terashima (Ehime U.), Y. Tsuboi (Chuo U.), H. Uchida (Kyoto U.), T. Yoneyama (Chuo U.), M. Yoshimoto (Ehime U.)
on 23 Apr 2025; 14:14 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Marina Orio (orio@astro.wisc.edu)

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We report that the XRISM/XTEND Transient Search source XRISM J1826-3651, observed on 2025-04-12 and reported in ATel #17145 was observed again with the Swift X-Ray Telescope (XRT) on 2025-04-22 for a total (non continuous) on-source time of 2642 s. The source is still X-ray luminous, and was detected with a count rate 0.022±0.004 cts/s at this position: alpha=18 26 08.16 and delta=-36 50 46.8, with a position uncertainty of 4.2 arcseconds. The spectrum is relatively hard and can be fitted with a power law, with photon index 1.9(+0.8/-0.6), absorbing column density N(H)=2.2(+3.6/-2.1) cm^-2, absorbed flux of 1.0±0.5 x 10^-12 erg/cm/^-2/s, and unabsorbed flux ~1.3 x 10 ^-12 erg/cm^-2/s. The most likely counterpart is the radio-loud quasar and blazar 1WGA J1826.1-3650 at redshift z=0.888 (Veron Cetty et al. 2010, A&A, 518, 10), which also corresponds to GAIA source 6728071805422016896, at 2.9 arcsec from the Swift XRT position. This object was serendipitously observed with ROSAT in X-rays as 1WGA J1826.1-3650 at comparable luminosity in 1992 March, so this is not the first X-ray active state, but X-ray observations in the intervening time are missing.