Safronov Regio

Safronov Regio (formerly Krun Macula) is the westernmost of the "Brass Knuckles", a series of equatorial dark regions on Pluto.

Observation and naming
Safronov Regio was first observed as the New Horizons spacecraft approached Pluto and its system of moons. As Pluto rotated, a series of equatorial dark regions were observed and informally nicknamed the Brass Knuckles, with Safronov Regio being the westermost of the dark regions. It was initially informally named Krun Macula after Krun, the greatest of the five Mandaean lords of the underworld. However, the International Astronomical Union (IAU) instead officially approved the name Safronov Regio in honor of Russian astronomer Viktor Safronov, an early proponent of the planetesimal hypothesis for Solar System formation. The name was approved on 22 September 2023.

Description
Safronov Regio is the third largest equatorial dark region on Pluto, after the Belton Regio and the Balrog Macula. It extends nearly to 180 degrees longitude, the Plutonian longitude opposite Charon.