MAXI/GSC detection of a new outburst from GRS 1716-249/GRO J1719-24 or a new X-ray transient MAXI J1719-254

ATel #9876; H. Negoro, T. Masumitsu, T. Kawase, K. Tanaka (Nihon U.), M. Serino (RIKEN), A. Tanimoto (Kyoto U.), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA), T. Mihara, M. Sugizaki, W. Iwakiri, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, N. Isobe, S. Sugita, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara, S. Harita, Y. Muraki (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R. Shomura (Osaka U.), M. Nakajima (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, S. Oda (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.) report on behalf of the MAXI team
on 19 Dec 2016; 13:03 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Hitoshi Negoro (negoro@phys.cst.nihon-u.ac.jp)

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At 13:37 UT on 2016 December 18, the MAXI/GSC nova-alert system triggered on X-ray enhancement at the position (R.A., Dec) = (259.9, -25.4). The source position could not be determined by the automatic fitting procedure due to the detection at the edge of the FOV. Instead, we obtained the position from a smoothed 4-10 keV X-ray image. The error radius of the source position is typically 0.2-0.3 deg (Negoro et al. 2016, PASJ, 68, S1), but currently the uncertainty of the position might be unexpectedly large. The position is consistent with that of the black hole candidate GRS 1716-249/GRO J1719-24. We, however, tentatively name the source MAXI J1719-254 until the confirmation.

The source is close to the sun (~ 7 deg) so that MAXI/GSC could not observe the source region from 2016 November 29 to December 17. As soon as the source entered the GSC FOV again, the enhancement was detected, which implies that the onset of the outburst started before the trigger time. The 4-10 keV X-ray flux is stable on timescales of hours, and roughly 150 mCrab on December 18.

GRS 1716-249/GRO J1719-24, the X-ray nova Ophiuchi 1993, was discovered in 1993 simultaneously by GRANAT/SIGMA (Ballet et al. 1993, IAU Circ. 5874) and CGRO/BATSE (Harmon et al. 1993, IAU Circ. 5874). The source was often active until 1995 (e.g., Revnivtsev et al. 1998, A&A, 331, 557 and Borozdin et al. 1995, IAU Circ. 6141), but no further activity has been reported (e.g., Chaty et al. 2002, MNRAS, 331, 1065).

We have not obtained an energy spectrum from this source, yet. But X-ray color images of the nova-alert system indicate that the spectrum is relatively soft, and unlikely to be a typical hard state spectrum of black hole binaries as reported in the previous outbursts in 1990's.

We encourage followup observations as soon as the source is far from the sun.

MAXI/GSC detection of this outburst