NGC 4603

During 1999, this galaxy was the subject of an extended study using the Hubble Space Telescope to locate Cepheid variable stars. A total of 43±7 were found, and the measurement of their periodicity gave a net distance estimate of 108.7+5.5
−4.9 Mly (33.3+1.7
−1.5 Mpc). This is consistent with the distance estimate determined through redshift measurements. As of the time of this study, NGC 4603 was the most distant galaxy for which a distance estimate had been made using Cepheid variable.

On May 21, 2008, supernova SN 2008cn was discovered at a position 23.″2 north and 4.″7 east of the galaxy center. It was determined to be a high-luminosity Type II-P supernova, with a progenitor tentatively identified as a red supergiant with 15 ± 2 solar masses. Based upon the yellowish color, it may have been a member of a binary star system.