Light curve of kilonova in NGC 4993

This plot shows how the brightness of the kilonova seen in the galaxy NGC 4993 changed when measured through different colour filters. In blue light the object faded rapidly, but at longer wavelengths, in the near infrared part of the spectrum, it brightened a little and then faded much more slowly. As a result this object changed colour from very blue to very red over the period of four weeks.