MAXI/GSC detection of a new X-ray transient MAXI J1749-310

ATel #13154; H. Negoro, M. Nakajima, W. Maruyama, M. Aoki, K. Kobayashi (Nihon U.), T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, M. Serino, S. Sugita, H. Nishida, A. Yoshida (AGU), Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, T. Sato (Chuo U.), M. Shidatsu (Ehime U.), N. Kawai, M. Oeda, K. Shiraishi (Tokyo Tech), S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, N. Isobe, 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) report on behalf of the MAXI team:
on 2 Oct 2019; 01:48 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

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MAXI/GSC detected a new outburst near the galactic center region, (l, b) = (358.7 deg, -1.9 deg). GSC data show highly variable X-ray flux changes (< 30 mCrab) on timescales of hours or less since 2019 September 29.

Assuming that the source flux was constant over 20 scan transits from 19:47 on September 29 to 10:29 on October 1, we obtain the source position at
(R.A., Dec) = (267.466 deg, -31.028 deg) = (17 49 51, -31 01 40) (J2000)
with a statistical 90% C.L. elliptical error region with long and short radii of 0.17 deg and 0.15 deg, respectively. The roll angle of the long axis from the north direction is 144.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scans was 22 +- 3 mCrab (4.0-10.0keV, 1 sigma error).

The X-ray burster GRS 1747-312 lies 0.326 arc-degree apart from the above source position, just outside of the error region even if the systematic uncertainty is taken into account. Then, we tentatively name the source MAXI J1749-310. We, however, can not exclude the possibility that the source is GRS 1747-312 because of further uncertainty of the position due to the detection near the edge of a detector though no X-ray burst-like event was detected, yet.

Following observations are encouraged to confirm the nature of the source.

Information on the detection of MAXI J1749-310