NGC 4603 is a spiral galaxy located a bit more than 100 million light years away in the constellation Centaurus. It’s a pure spiral galaxy with relatively loosely wound arms. During 1999, this galaxy was the subject of an extended study using the Hubble Space Telescope to locate Cepheid variable stars. Over 40 were found, and the measurement of their periodicities gave a net distance estimate of 108.7, +5.5,−4.9 million light years. That was consistent with the distance estimate determined through redshift measurements. As of the date of that study, NGC 4603 was the most distant galaxy for which a distance estimate had been made using Cepheid variable.
Image Credit: NASA