New type I outburst of GRO J1008-57

ATel #8547; P. Kretschmar (ESA/ESAC), M. Kuehnel (Remeis-Observatory & ECAP/Univ. Erlangen), M. Nakajima (Nihon U.), R. E. Rothschild (UC San Diego), E. Laplace (IAA Tuebingen), E. Salazar (ESA/ESAC), T. Mihara (RIKEN), I. Kreykenbohm (Remeis-Observatory & ECAP/Univ. Erlangen), and C. A. Wilson-Hodge (NASA-MSFC)
on 15 Jan 2016; 09:36 UT
Credential Certification: Peter Kretschmar (Peter.Kretschmar@esa.int)

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The Be X-ray binary GRO J1008-57 has begun another regular outburst. At the time of writing, daily averaged flux levels were 41 ± 11 mCrab (0.15± 0.04 counts/sec/cm^2, 2-20 keV) in MAXI and ~60 mCrab (~0.013 count/cm^2/s) in the Swift BAT monitor data. The beginning of the outburst is visible from orbital phase -0.08 according to the ephemeris of Kuehnel et al. (ATel #4564). This orbital phase is consistent with previous type I outbursts of the source as found by Kuehnel et al. (2013). From their outburst history we expect the peak of the outburst in the time range of January 19 to 28. If the outburst will be of a similar brightness as the last four outbursts around the periastron we expect a flux of 100-150 mCrab within 15-50 keV. GRO J1008-57 has shown very regular activity for the last few years including a highly interesting multiple outburst in 2014 and 2015 (ATel #6917, #6465, #6630, #6656, #6664, #6819, #6823) followed by a normal type I outburst (ATel #7490). Multiwavelength observations of the source are encouraged to shed light on the similarities and differences to the previously observed events. The further evolution of the outburst can be followed at the BeXRB monitor page http://integral.esac.esa.int/bexrbmonitor/webpage_oneplot.php or the specific page http://integral.esac.esa.int/bexrbmonitor/Plots/sim_plot_GROJ1008-57 combining data from MAXI http://maxi.riken.jp/top/index.php?cid=1&jname=J1009-582, Swift/BAT http://swift.gsfc.nasa.gov/results/transients/GROJ1008-57/ and Fermi/GBM http://gammaray.msfc.nasa.gov/gbm/science/pulsars/lightcurves/groj1008.