738 Alagasta () is a main belt asteroid. It was discovered from Heidelberg on 7 January 1913 by German astronomer Franz Kaiser. The asteroid was named in honor of Gau-Algesheim, previously Alaghastesheim, which is the home city of the discoverer's family. This body is orbiting at a distance of with a period of and an eccentricity of 0.055. The orbital plane is inclined at an angle of 3.53ð to the plane of the ecliptic.
Photometric measurements made of the asteroid during 2015 produced a light curve that showed a rotation period of with a brightness variation of 0.11 in magnitude. The asteroid is roughly 63 km in diameter and has a low albedo.