MAXI/GSC detection of an X-ray outburst from the high mass X-ray binary pulsar GS1843-02 (4U 1850-02)
ATel #9339; M. Nakajima (Nihon U.), S. Harita (Tokyo Tech), T. Mihara (RIKEN), S. Ueno, H. Tomida, S. Nakahira, M. Ishikawa, Y. Sugawara (JAXA), M. Sugizaki, M. Serino, 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, Y. Muraki (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, Y. Kitaoka (AGU), H. Tsunemi, R. Shomura (Osaka U.), H. Negoro, K. Tanaka, T. Masumitsu, T. Kawase (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.), Y. Tsuboi, Y. Nakamura, R. Sasaki (Chuo U.), M. Yamauchi, K. Furuya (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. E. Nakagawa (JAMSTEC)
on 8 Aug 2016; 09:27 UT
Credential Certification: Motoki Nakajima (nakajima.motoki@nihon-u.ac.jp)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
Referred to by ATel #: 11033
The MAXI/GSC nova-alert system (Negoro et al. 2016) have detected a weak X-ray brightening from a position of the Galactic plane l=30 deg on 2016 August 6.28 (MJD 57606.28). We obtain the source position at (R.A., Dec) = (281.838 deg, -2.566 deg) with a statistical 90% C.L. elliptical error region with long and short radii of 0.57 deg and 0.49 deg, respectively. The roll angle of long axis from the north direction is 23.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). At almost the same time, Swift/BAT observed an X-ray brightening from a position of (R.A., Dec) = (282.077 deg, -2.446 deg) (GCN#19781) which is consistent with the MAXI/GSC trigger position. The authors tentatively concluded that the triggered outburst is caused by high mass X-ray binary GS1843-02 (4U 1850-03 or 2S 1845-024). According to the orbital parameters of GS1843-02 (Porb=242.18 d, T0=49616.48(MJD) ; Finger et al. 1999), the onset orbital phase of the current X-ray brightening is turned out to be ~0.99, which is consistent with the previous outburst onsets observed on 2015 April (Atel#7386) and 2015 December (Atel#8392). In addition, the observed fluxes, 0.0926 +/- 0.0185 counts/s/cm2 (26 +/- 5 mCrab) in 2-20 keV band and 0.0151 +/- 0.0012 counts/s/cm2 (69 +/- 6 mCrab) in 15-50 keV band, on August 6, nicely matched with that of the previous outburst from GS1843-02 (Atel#8392). Therefore, we conclude that the event observed by MAXI/GSC is a normal outburst from GS1843-02.
The latest source flux can be checked at the following pages;
MAXI(http://maxi.riken.jp/top/index.php?cid=1&jname=J1848-024),
Swift/BAT(http://swift.gsfc.nasa.gov/results/transients/weak/GS1843-02/),
Fermi/GBM(http://gammaray.msfc.nasa.gov/gbm/science/pulsars/lightcurves/2s1845.html), and
the BeXRB monitor page(http://integral.esac.esa.int/bexrbmonitor/webpage_oneplot.php).
