ATel #10533: INTEGRAL detection of re-brightening from GRO J1008-57

V. Sguera, A. Bazzano, P. Ubertini, M. Fiocchi, J. Chenevez, L. Sidoli, E. Kuulkers, V. A. Lepingwell, J. Bird

Research output: Other contributionNet publication - Internet publicationResearch

Abstract

The transient Be HMXB GRO J1008-57, recently detected during a type I X-ray outburst (ATels #10418, #10466) with a predicted peak on MJD 57909.37 or 5 June 2017 (based on the times of maximum flux, epoch=54416.65 MJD and Porb=249.48 days; Kuhnel et al. 2013), is currently undergoing a peculiar enhanced X-ray activity starting on MJD 57922 (17 June 2017) as detected by MAXI/GSC (ATel #10529).

GRO J1008-57 was in the field of view of INTEGRAL during recent Galactic Plane Scan observations (GPS) regularly performed in the last week.

The source was detected by IBIS/ISGRI at about 9 sigma level (22-60 keV, 5.8 ks of effective exposure time) during GPS observations in revolution 1828 starting on MJD 57920.8 (16 June 2017 at 19:12 UTC). The measured average flux was 25.3 +/- 2.8 mCrab. The source was also in the JEM-X monitor field of view for 1.8 ks effective exposure, the measured average fluxes were 25 +/- 4 mCrab (3-10 keV) and 15 +/- 6 mCrab (10-25 keV).
During the subsequent GPS observations (revolution 1829, starting on MJD 57922), the source was detected by IBIS/ISGRI at 11.8 sigma level (22-60 keV, 4.3 ks of effective exposure time) with an enhanced average flux of 33.1 +/- 2.8 mCrab. The source was also in the JEM-X monitor field of view for 3.3 ks effective exposure, the measured average fluxes were 25 +/- 3 mCrab (3-10 keV) and 38.0 +/- 10.5 mCrab (10-25 keV).
Finally, during the most recent GPS observations (revolution 1831, starting on MJD 57928.7 or 24 June at 16:48 UTC) the source was detected by IBIS/ISGRI at 15.6 sigma level (22-60 keV, 4.3 ks of effective exposure time) with a further enhanced average flux of 43.6+/-2.8 mCrab. The source was also in the JEM-X monitor field of view for 3.4 ks effective exposure, the measured average fluxes were 30 +/- 3 mCrab (3-10 keV) and 52 +/- 12 mCrab (10-25 keV).

GRO J1008-57 is clearly undergoing a peculiar re-brightening especially above 20 keV, confirming the enhanced X-ray activity detected by MAXI/GSC below 20 keV.
Original languageEnglish
Publication date26 Jun 2017
Number of pages1
Publication statusPublished - 26 Jun 2017
SeriesThe Astronomer's telegram

Cite this

Sguera, V., Bazzano, A., Ubertini, P., Fiocchi, M., Chenevez, J., Sidoli, L., Kuulkers, E., Lepingwell, V. A., & Bird, J. (2017, Jun 26). ATel #10533: INTEGRAL detection of re-brightening from GRO J1008-57. The Astronomer's telegram http://www.astronomerstelegram.org/?read=10533