1628 Strobel, provisional designation 1923 OG, is a carbonaceous asteroid from the outer region of the asteroid belt, about 57 kilometers in diameter. It was discovered by German astronomer Karl Reinmuth at Heidelberg Observatory on 11 September 1923. The C-type asteroid orbits the Sun at a distance of 2.8–3.2 AU once every 5.22 years (1,908 days). Its orbit shows an eccentricity of 0.07 and is tilted by 19 degrees to the plane of the ecliptic. It has a rotation period of 9.52 hours and an albedo of 0.05 to 0.06, based on the surveys carried out by IRAS, Akari, WISE and NEOWISE.