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The outburst detected by MAXI/GSC (ATel. 10803) was not from LS I +61 303 but from the new X-ray transient Swift J0243.6+6124

ATel #10813; S. Sugita (Tokyo Tech), H. Negoro (Nihon U.), S. Nakahira, W. Iwakiri (RIKEN), S. Ueno, H. Tomida, M. Ishikawa, Y. Sugawara, N. Isobe, R. Shimomukai (JAXA), T. Mihara, M. Sugizaki, M. Shidatsu, F. Yatabe, Y. Takao, M. Matsuoka (RIKEN), N. Kawai, T. Yoshii, Y. Tachibana, S. Harita, K. Morita (Tokyo Tech), A. Yoshida, T. Sakamoto, M. Serino Y. Kawakubo, Y. Kitaoka, T. Hashimoto (AGU), H. Tsunemi, T. Yoneyama (Osaka U.), M. Nakajima, T. Kawase, A. Sakamaki (Nihon U.), Y. Ueda, T. Hori, A. Tanimoto, S. Oda (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki, H. Kawai (Chuo U.), M. Yamauchi, C. Hanyu, K, Hidaka (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team:
on 4 Oct 2017; 00:35 UT
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

Subjects: X-ray

Referred to by ATel #: 10907

As reported by Kennea et al. (GCN #21963, also Kennea et al. ATel #10809), the new transient X-ray pulsar Swift J0243.6+6124 (Cenko et al. GCN #21960, ATel #10809) is positionally consistent with the transient source that MAXI/GSC detected on September 29 (Sugita et al. ATel #10803).

The source flux obtained with MAXI/GSC has gradually increased since September 19 (ATel #10803). On October 3, the 2-4 keV and 4-10 keV X-ray fluxes reached (51.9+/-21)e-3 photons/s/cm2 (~47 mCrab) and (46.2+/-18.8)e-3 photons/s/cm2 (~41 mCrab), respectively. The GSC spectrum shows a hard power-law with a photon index of ~1. All these properties are consistent with those of Swift J0243.6+6124. Thus, the two sources are thought to be identical, and the outburst was not from LS I +61 303. We apologize to all the observers who observed LS I +61 303 by our first telegram.