The Ligo scientific collaboration has discovered the third confirmed gravitational wave event, GW170104. Several Indian and international astronomy groups searched for corresponding electromagnetic signals in the sky. The Cadmium Zinc Telluride Imager (CZTI) on AstroSat conducted the most sensitive search for short duration X-ray flashes associated with this event, but did not find anything. The Hawaii-based ATLAS group found a transient optical source, which was thought to be related to GW170104.

The CZTI team, in collaboration with the international GROWTH collaboration, studied this transient extensively, and proved that it was not the counterpart of GW170104. Instead, it was a Gamma ray burst event caused by the explosive death of a massive star in a galaxy several billion light years away giving birth to a new black hole.

Further details are provided in http://astrosat-ssc.iucaa.in/?q=press-release-gw170104