An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

A person or thing that corresponds to or has the same function as another person or thing in a different place or situation (OxfordDictionaries.com).
→ electromagnetic counterpart, → optical counterpart, → radio counterpart.

M.E., from O.Fr. contrepartie, from contre "facing, opposite," → counter-, + partie "copy of a person or thing," originally feminine p.p. of partir "to divide."

Hamtâ "counterpart, resembling, equal," from ham- "together, with; same, equally, even," → com-, + tâ "fold, plait, ply; piece, part," also a multiplicative suffix; Mid.Pers. tâg "piece, part."

An → electromagnetic signal associated with the location on the sky and the time of a → gravitational wave event. The electromagnetic signal is predicted by models to be associated with the → merger of a → compact binary star system composed of two → neutron stars (NS) or a neutron star and a → black hole (BH). Accordingly, the gravitational waves are accompanied by a short-duration → gamma-ray burst (GRB) powered by the → accretion of material that remains in a → centrifugally supported → torus around the BH following the merger. NS-NS/BH-NS mergers are also predicted to be accompanied by a more isotropic counterpart, commonly known as a → kilonova. Kilonovae are day to week-long thermal, → supernova-like → transients, and are powered by the → radioactive decay of heavy, neutron-rich elements synthesized by the → r-process in the expanding merger ejecta (Li and Paczynski 1998). The first detection of an electromagnetic counterpart to gravitational waves belongs to → GW170817.

→ electromagnetic; → counterpart.

An astronomical object with usually weak emission in the → visible found to be the optical representation of the object radiating chiefly in other → wavelengths of the → electromagnetic spectrum.

→ optical; → counterpart.

The representation in → radio wavelengths of an astronomical object that has emission in other parts of the → electromagnetic spectrum.

→ radio; → counterpart.