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Short X-ray Transient Detection by MAXI/GSC

ATEL # 2990; H. Tomida (JAXA), T. Yamamoto (RIKEN), H.Negoro (Nihon U.), M. Serino, T. Mihara, M. Sugizaki, Y.E. Nakagawa, T. Sootome, M. Matsuoka (RIKEN), N. Kawai, M. Morii, K. Sugimori, R. Usui (Tokyo Tech), S. Ueno, M. Kohama, M. Ishikawa (JAXA), A. Yoshida, K. Yamaoka, S. Nakahira (AGU), H. Tsunemi, M. Kimura (Osaka U.), M. Nakajima, H. Ozawa, F. Suwa (Nihon U.), Y. Ueda, N. Isobe, S. Eguchi, K. Hiroi, M. Shidatsu (Kyoto U.), A. Daikyuji (Miyazaki U.), A. Uzawa, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team
on 31 Oct 2010; 9:49 UT
Password Certification: Hiroshi Tomida (

Subjects: X-ray, Transients

At the scan transit, MAXI/GSC detected a transient X-ray source, which was present at least for 16 seconds within the 45 seconds triangular transit response of MAXI/GSC. The light curve without the triangular response correction shows a sharp rise (~2 s) and a slow decay (>14 s). The peak of the count rate was at UT 2010-10-30T10:09:07. Assuming constant flux over the transit, the source location is determined as

(R.A., Dec) = (+279.98 deg, 1.85 deg) = (18 39 55, +01 51 00) (J2000)

We obtain a rectangular error box with the following corners:

(R.A., Dec) = (+280.75 deg, +2.45 deg) = (18 43 00, +02 27 00)(J2000)
(R.A., Dec) = (+280.44 deg, +2.71 deg) = (18:41:46, +02 42 36)(J2000)
(R.A., Dec) = (+279.22 deg, +1.25 deg) = (18:36:53, +01 15 00)(J2000)
(R.A., Dec) = (+279.52 deg, +0.99 deg) = (18:38:05, +00 59 24)(J2000)

The preliminary flux (4-10keV) of the source is at least 250 mCrab, and the spectrum can be represented with an absorbed black-body model of ~1 keV. It is likely that this is an X-ray burst from a galactic source. There are at least two previously cataloged X-ray sources in the error region, 1RXS J183953.1+014250 and 1RXS J184107.2+015024. There was no significant detection at the transit location in the previous and following orbits (92min before and after the detection) with an upper limit of 20mCrab.

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R. E. Rutledge , Editor
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