MAXI/GSC detection of a new outburst of the recurrent nova RS Oph

ATel #14846; M. Shidatsu (Ehime U.), H. Negoro (Nihon U.), T. Mihara (RIKEN), M. Nakajima, K. Kobayashi, K. Asakura, K. Seino (Nihon U.), T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, K. Komachi, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.), N. Kawai, M. Niwano, R. Hosokawa (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA), Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, Y. Goto, R. Uematsu (Kyoto U.), H. Tsunemi (Osaka U.), M. Yamauchi, Y. Nonaka, T. Sato, R. Hatsuda, R. Fukuoka (Miyazaki U.), T. Kawamuro (UDP/NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC)
on 11 Aug 2021; 08:33 UT
Credential Certification: Megumi Shidatsu (shidatsu.megumi.wr@ehime-u.ac.jp)

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The MAXI/GSC nova alert system detected an X-ray source consistent with the recurrent nova RS Oph at 2021 August 10th UT 18:28 (MJD 59436.769). The triggered position was (R.A., Dec) = (267.403 deg, -6.805 deg) = (17 49 36, -06 48 17) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.24 deg and 0.22 deg, respectively. The roll angle of long axis from the north direction is 141.0 deg counterclockwise. It is likely that MAXI detected the new outburst of RS Oph, following the recent optical and gamma-ray detections (VSNET alert N.26131, ATels #14834, #14838, #14840, #14844, #14855). The MAXI/GSC light curve suggests that the X-ray brightening started around MJD 59435.5, which is later than the onset of the optical outburst. The latest 1-day averaged intensity was 36 +/- 1 mCrab (4-10 keV) on MJD 59436. The flux is rising at MJD 59437.0. The source was outside MAXI's field of view from MJD 59434.45 - MJD 59435.03, in which there were the optical onset and the Fermi/LAT detection of gamma-ray. Before this period the source was not detected significantly. Follow-up observations are encouraged.

MAXI/GSC light curve