Follow-up survey for the binary black hole merger GW200224_222234 using Subaru/HSC and GTC/OSIRIS

Understand

The LIGO/Virgo detected a gravitational wave (GW) event, named GW200224_222234 (a.k.a.

• S200224ca) and classified as a binary-black-hole coalescence, on February 24, 2020.
• Given its relatively small localization skymap (71 deg$^2$ for a 90% credible region; revised to 50 deg$^2$ in GWTC-3), we performed target-of-opportunity observations using the Subaru/Hyper Suprime-Cam (HSC) in the $r2$- and $z$-bands.
• Observations were conducted on February 25 and 28 and March 23, 2020, with the first epoch beginning 12.3 h after the GW detection.