INTEGRAL detection of 2S 1553-542

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

*Corresponding author for this work

Research output: Other contributionNet publication - Internet publicationResearch


The transient source 2S 1553−542 is an accreting X-ray pulsar with a Be optical companion discovered by the SAS-3 observatory in 1975 (Apparao et al., 1978, Nature, 271, 225). Increased activity from the source was detected in 2007 by Swift/BAT and Swift/XRT instruments (ATel #1345, #1371) and one year later by RXTE/PCA (ATel #1373). Activity from this source was also recently reported by Fermi/GBM and Swift/MAXI (ATel #14301 and #14308)

During a recent INTEGRAL public observation of the Galactic Plane (revolution 2321), performed between 2021-01-17 13:41:03 and 2021-01-18 16:58:14 UTC, activity from this transient was detected. The 22-60 keV IBIS/ISGRI flux corresponds to 26.1 ± 2.2 mCrab (2.8 ± 0.2 x 10-10 erg cm-2 s-1) with an effective exposure time of 16 ks.

2S 1553-542 was within the JEM-X field of view at 71 sigmas in the combined JEM-X1 and JEM-X2 mosaic for a total effective exposure of 40.8 ks on the source. The measured fluxes are 57 ± 1 mCrab (8.6 ± 0.1 x 10-10 erg cm-2 s-1) and 58 ± 4 mCrab (6.1 ± 0.4 x 10-10 erg cm-2 s-1) in the energy bands 3-10 and 10-25 keV, respectively.

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

Results from the Galactic Plane Scanning are publicly available at:
Original languageEnglish
Publication date20 Jan 2021
Publication statusPublished - 20 Jan 2021
SeriesThe Astronomer's telegram
NumberATel #14335


  • X-ray
  • Transient
  • Pulsar


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