MAXI/GSC detection of the fast X-ray transient XTE J1901+014

ATel #13328; T. Sato (Chuo U.), H. Negoro (Nihon U), W. Iwakiri (Chuo U.), T. Mihara, C. Guo, Y. Zhou, T. Tamagawa, M. Matsuoka (RIKEN), M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi, R. Takagi (Nihon U.), T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, R. Sasaki, H. Kawai (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, R. Shimomukai, M. Tominaga (JAXA), Y. Ueda, A. Tanimoto, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake (Kyoto U.), H. Tsunemi, T. Yoneyama, K. Asakura, S. Ide (Osaka U.), M. Yamauchi, S. Iwahori, Y. Kurihara, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC)
on 4 Dec 2019; 01:38 UT
Credential Certification: Wataru Iwakiri (wataru.iwakiri@riken.jp)

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The MAXI/GSC nova alert system triggered on a bright X-ray transient source at 10:14 UT on December 03, 2019. Assuming that the source flux was constant over two scan transients at 10:14 and 11:47 UT, we obtain the source position at (R.A., Dec) = (285.276 deg, 1.494 deg) = (19 01 06, +01 29 38) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.26 deg and 0.19 deg, respectively. The roll angle of long axis from the north direction is 65.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). This position is consistent with that of the fast X-ray transient XTE J1901+014. The 4-10 keV flux averaged over the scans was 73 +- 12 mCrab. The peak flux of 84 +- 20 mCrab was observed at the scan transit at 10:14 on December 03, 2019. The flux decayed to an upper limit of ~20 mCrab at the next scan performed 92 minutes later.
XTE J1901+014 was discovered in 2002 by the RXTE observatory (Remillard and Smith, ATel #88). Several rapid outbursts from this source have reported (Smith et al., ATel #1268; Krimm et al., ATel #2375). Optical photometry of the field suggests a low mass companion and the source may be the first low-mass fast X-ray transient, but the true nature of the source is still in question(Karasev, Lutovinov & Burenin, 2008, Astron. Lett., 34, 753; Karasev et al. 2012, Astron. Lett., 38, 629). We encourage further observations of this source in order to determine the nature of the source.