[ Previous | Next | ADS ]

Optical activity of the transient X-ray source A0535+26/HDE 245770

ATel #6528; F. Giovannelli (INAF-Istituto di Astrofisica e Planetologia Spaziali, Roma, Italy), G. S. Bisnovatyi-Kogan ( IKI - Space Research Institute, Moscow, Russia), I. Bruni (INAF-Osservatorio Astronomico di Bologna, Stazione astronomica di Loiano, Italy), F. Martinelli (Montecatini Val di Cecina Astronomical Centre, Montecatini Val di Cecina, Italy), M. Monaci (Montecatini Val di Cecina Astronomical Centre, Montecatini Val di Cecina, Italy), C. Rossi (Dpt. Of Physics, Sapienza University, Roma, Italy)
on 3 Oct 2014; 10:35 UT
Credential Certification: Franco Giovannelli (franco.giovannelli@iaps.inaf.it)

Subjects: Optical

Referred to by ATel #: 6569, 6585

We planned optical photometry of HDE 245770 at the Loiano observatory with the 1.52 m Cassini telescope, and at the Montecatini Val di Cecina Astronomical Center 36 cm telescope around the periastron passage of the neutron star A0535+26 (JD 2456821) following the ephemeris of Giovannelli et al.: 2013, A&A, 560, A1G (JD_opt-outb = JD_0(2444944) +- n(111.0 +- 0.4) days). This passage is just 107 orbital periods after the 811205-E. The results of photometry shows an enhancement in the optical luminosity in V band of about 0.03 mag around the periastron passage. This is a strong indication that the X-ray pulsar is close to experience an X-ray outburst after about 8 days from the periastron passage, with an expected intensity of about 10-100 mCrab. X-ray measurements are strongly required.