Optical follow-up of IGR J06074+2205
ATel #17716; Roberto Nesci (INAF/IAPS), Mariateresa Fiocchi (INAF/IAPS), Antonio Vagnozzi (MPC589)
on 10 Mar 2026; 23:18 UT
Credential Certification: Roberto Nesci (roberto.nesci@inaf.it)
Subjects: Optical, X-ray, Binary, Neutron Star, Variables
Nakajima et al. in ATel #17714 reported an X-ray alert from MAXI/GSC of the HMXB IGR J06074+2205 with peak intensity on March 7 2026 at 0.030 c/s/cm2. This epoch is in fair agreement with the expectation from the recurrence period of 80 +/-2 days given by Mihara et al. in ATel #16351.
According to our spectroscopic monitoring of the source with the S.Lucia di Stroncone (MPC 589) 50 cm telescope, started in January 2024, the H-alpha equivalent width (E.W.) emission has an oscillating behaviour with 570 days time scale, and was steadly decreasing since its maximum of -12 Angstrom in September 2025 (see plot below). The E.W. on March 10 2026 is -6.9 Angstrom, indicating a circumstellar disk of average extension: we would expect therefore an X-ray outburst substantially fainter than those of September 2025 or March 2024, when the H alpha E.W. was about -12 Angstrom.
Using the MAXI on-demand system (https://maxi.riken.jp/mxondem/) we found a count rate of 0.08 ph/s/cm2 in the strong outburst of March 2024 in the 2-6 keV band, and a similar value just before the peak of the strong outburst of September 2025. Therefore, the relatively low value of 0.03 ph/s/cm2 of March 7 2026 is in fair agreement with the expectation from the H alpha E.W., supporting the model that the interaction of the Pulsar with the circumstellar disk of the Be star is the main cause of the X-ray outburst.
H alpha E.W. light curve
