Transient Activity in recent GPS observations

ATel #13255; Lepingwell V. A. (Univ. of Southampton, UK), Onori F. (INAF-IAPS Roma, Italy), Bird A. J. (Univ. of Southampton, UK), Bazzano A., Fiocchi M., Natalucci, L., F., Ubertini P. (INAF-IAPS Roma, Italy), Bozzo E. (ISDC; Geneva), Sguera V., Masetti N. (INAF-OAS, Bologna, Italy), Knudsen M., Rasmussen H. J., Chenevez J. (DTU Space, Denmark)
on 2 Nov 2019; 18:46 UT
Credential Certification: Victoria Lepingwell (V.A.Lepingwell@soton.ac.uk)

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During the recent INTEGRAL observations of the Galactic Plane Scan (PI: Dr. A. Bazzano), the IBIS/ISGRI instrument detected emission from the transient sources SWIFT J1858-0814, EXO 1846-031 and SWIFT J1845.7-0037 at significances of 14.1, 11.2 and 6.5 sigma, respectively. The sources were detected during scans performed in revolution 2154 (between 2019-10-30 07:37:14 UTC and 2019-10-31 13:44:02 UTC).

SWIFT J1858.6-0814 was first detected on 2018 October 31 (ATel #12151) and was observed in both soft X-rays (ATels #12158, #12160, #12163, #12164) and hard X-rays (ATel #12167). SWIFT J1858-0814 was observed by IBIS/ISGRI in the 22-60 keV energy range at RA (J2000) = 284.62 dec (J2000)= -8.23. The 22-60 keV flux measured over the whole GPS observation is F_22-60 = 2.35±0.16 x10^-10 erg cm^-2 s^-1 (21.7±1.5 mCrab) for an effective exposure time of 8.8 ks.

The galactic black hole candidate EXO 1846-031 was first detected in 1985 and only one period of renewed activity has been reported in July and August 2019 (ATels #12968, #12969, #12976, #12977 #12991, #12992, #13012, #13036, #13037). EXO 1846-031 was observed by IBIS/ISGRI in the 22-60 keV energy range at RA (J2000) = 282.32 dec (J2000)= -3.06. The 22-60 keV flux measured over the whole GPS observation is F_22-60 = 1.43±0.15 x10^-10 erg cm^-2 s^-1 (13.2±1.3 mCrab) for an effective exposure time of 11.0 ks. The X-ray transient Swift J1845.7-0037 first detected in 2012 was recently found to be in outburst again (ATels #13189, #13191, #13195, #13208, #13211, #13214, #13218, #13219, #13220, #13222, #13223).

SWIFT J1845.7-0037 was observed by IBIS/ISGRI in the 22-60 keV energy range at RA (J2000) = 281.42 dec (J2000)= -0.64. The 22-60 keV flux measured over the whole GPS observation is F_22-60 = 9.23± 1.50 x10^-11 erg cm^-2 s^-1 (8.5±1.4 mCrab) for an effective exposure time of 10.5 ks.

All the data have been analysed using the Offline Software Analysis version 11.0 (OSA11).

The source field will be observed again during the next days in the framework of the Galactic Plane Scan program (PI: Dr. A. Bazzano).

Results from the INTEGRAL Galactic Plane Scanning are publicly available at: http://gps.iaps.inaf.it/