MAXI/GSC detection of a new soft X-ray transient MAXI J1647-227

ATel #4175; H. Negoro (Nihon U.), S. Nakahira (JAXA), Y. Tsuboi, M. Higa (Chuo U.) M. Morii (Tokyo Tech), T. Yamamoto (RIKEN), S. Ueno, H. Tomida, M. Ishikawa (JAXA), T. Mihara, M. Serino, M. Sugizaki, J. Sugimoto, M. Matsuoka (RIKEN), N. Kawai, R. Usui, K. Ishikawa (Tokyo Tech), M. Nakajima, M. Asada, H. Sakakibara, N. Serita (Nihon U.), A. Yoshida (AGU), H. Tsunemi, M. Kimura (Osaka U.), Y. Ueda, K. Hiroi, M. Shidatsu, R. Sato (Kyoto U.), M. Yamauchi, Y. Nishimura, T. Hanayama, K. Yoshidome (Miyazaki U.), K. Yamaoka (Waseda U.) report on behalf of the MAXI team
on 15 Jun 2012; 12:57 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

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On 14 June 2012, the MAXI/GSC detects enhanced soft X-ray emission at a posittion:

(R.A., Dec) = (+251.96 deg, -22.75 deg) = (16 47 50, -22 44 59) (J2000)

with a statistical uncertainty of 0.54 deg at the 90% confidence limit and an additional systematic uncertainty of 0.1 deg (90% containment radius). There is no bright known X-ray source within the error circle, and we tentatively name the source MAXI J1647-227.

The enhanced emission has been recognized since 12 June 2012 from daily images, and the one-day averaged fluxes on 14 June are 23+-6 mCrab in the 2-4 keV band and 33+-7 mCrab in the 4-10 keV band.

We note that there is a nearby star forming region Rho Oph dark cloud, separated by about 1 degree from the source. It is also possible that the source is a new black hole candidate or neutron star in the soft state. Followup observations are encouraged to reveal the nature of the source.

The latest light curves and images of MAXI J1647-227 by MAXI/GSC will be placed at the following URL: http://maxi.riken.jp/top/index.php?cid=1&jname=J1647-227

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