We present our observations of electromagnetic transients associated with GW170817/GRB 170817A using optical telescopes of Chilescope observatory and Big Scanning Antenna (BSA) of Pushchino Radio Astronomy Observatory at 110 MHz. The Chilescope observatory detected an optical transient of ∼19^m on the third day in the outskirts of the galaxy NGC 4993; we continued observations following its rapid decrease. We put an upper limit of 1.5 × 10⁴ Jy on any radio source with a duration of 10–60 s, which may be associated with GW170817/GRB 170817A. The prompt gamma-ray emission consists of two distinctive components—a hard short pulse delayed by ∼2 s with respect to the LIGO signal and softer thermal pulse with T ∼ 10 keV lasting for another ∼2 s. The appearance of a thermal component at the end of the burst is unusual for short GRBs. Both the hard and the soft components do not satisfy the Amati relation, making GRB 170817A distinctively different from other short GRBs. Based on gamma-ray and optical observations, we develop a model for the prompt high-energy emission associated with GRB 170817A. The merger of two neutron stars creates an accretion torus of ∼10⁻² M _⊙, which supplies the black hole with magnetic flux and confines the Blandford–Znajek-powered jet. We associate the hard prompt spike with the quasispherical breakout of the jet from the disk wind. As the jet plows through the wind with subrelativistic velocity, it creates a radiation-dominated shock that heats the wind material to tens of kiloelectron volts, producing the soft thermal component.

Periodicities observed in two fast radio burst (FRB) sources (16 days in FRB 180916.J0158+65 and 160 days in FRB 121102) are consistent with that of tight, stellar-mass binary systems. In the case of FRB 180916.J0158+65 the primary is an early OB-type star with the mass-loss rate yr⁻¹, and the secondary is a neutron star. The observed periodicity is not intrinsic to the FRB’s source, but is due to the orbital phase-dependent modulation of the absorption conditions in the massive star’s wind. The observed relatively narrow FRB activity window implies that the primary’s wind dynamically dominates that of the pulsar, , where L _sd is the pulsar spin-down, is the primary’s wind mass-loss rate, and v _w is its velocity. The condition η ≤ 1 requires a mildly powerful pulsar with L _sd ≲ 10³⁷ erg s⁻¹. The observations are consistent with magnetically powered radio emission originating in the magnetospheres of young, strongly magnetized neutron stars, the classical magnetars.