Strong X-ray outburst of IGR J06074+2205
ATel #17424; Roberto Nesci (INAF/IAPS), Mariateresa Fiocchi (INAF/IAPS), Antonio Vagnozzi (MPC589)
on 28 Sep 2025; 05:14 UT
Credential Certification: Roberto Nesci (roberto.nesci@inaf.it)
Subjects: X-ray, Binary, Pulsar
IGR J06074+2205 is a High Mass X-ray Binary made of a B0.5e star and a pulsar of 324 s period. The system showed in the last years recurrent X-ray flares, which are believed to be produced by the crossing of the circumstellar disc of the Be star by the companion pulsar. This object has been extensively studied recently by Chhotaray et al. (2024 MNRAS 534 2830) who confirmed the orbital period of 80 days suggested by Mihara et al. (2023, ATel #16351).
Our spectroscopic monitoring with the 50 cm telescope of the MPC589 observatory shows a strong H-alpha emission (11 Angstrom equivalent width) suggesting that a strong outburst should happen around next periastron passage of the pulsar around 2025-09-24. A daily monitoring with Swift/XRT started on September 19 showing the source at the quiescent level of 0.03 c/s.
The X-ray flux started to increase on 2025-09-23, reaching the value of 1.99 c/s on 2025-09-27T18:55. It is the largest X-ray flux ever observed for this source (ATels #17152, #16899, #16525). Swift/XRT observations will continue in the next few days. Follow-up with other X-ray instruments is encouraged.
