What is the observational phenomenon when a neutron star merger is seen via both light and gravitational waves?

Answer

Multi-messenger astronomy

When neutron star mergers create both significant gravitational waves and a burst of light (Kilonovae), astronomers can observe the event using both gravitational and electromagnetic means, which is termed multi-messenger astronomy.

What is the observational phenomenon when a neutron star merger is seen via both light and gravitational waves?
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