Rise in optical activity of HDE245770/A0535+26 system
ATel #8024; F. Giovannelli (INAF-Istituto di Astrofisica e Planetologia Spaziali, Roma, Italy), C. Rossi (Dpt of Physics, La Sapienza University, Roma, Italy), I. Bruni (INAF-Osservatorio Astronomico di Bologna, Stazione Astronomica di Loiano, Italy), G. S. Bisnovatyi-Kogan (IKI â Space Research Institute, Moscow, Russia), J. Salas Procas (Agrupacion Astronomica de Huesca, Spain), F. Martinelli and M. Monaci (Astronomical Centre, Lajatico, Italy
on 9 Sep 2015; 07:22 UT
Credential Certification: Corinne Rossi (corinne.rossi@uniroma1.it)
Subjects: Optical, X-ray, Binary, Neutron Star
Referred to by ATel #: 8055
We continued the monitoring of HDE 245770 in V band around the periastron passage of the
neutron star A0535+26 (JD 2457265) following the ephemeris of Giovannelli et al.: 2013, A&A, 560, A1G [JD_opt-out = JD_0(2444944) +- n(111.0 +- 0.4) days].
This passage is just 111 orbital periods after the 811205-E.
The luminosity in V band shows an increase, reaching about 0.5 mag at JD 2457264.584.
This is an indication that the X-ray pulsar is close to experience an X-ray outburst within about 8 days with an expected intensity of about 3.0+/-0.5 Crab, following the relationship X-ray intensity vs Delta V magnitude (Giovannelli et al.: 2015, Acta Astronomica 65, 107).
Coordinated optical and X-ray measurements are strongly required.
