NGC 4603

NGC 4603 is a spiral galaxy located about 107^[2] million light years away in the constellation Centaurus. It is a member of the Centaurus Cluster of galaxies, belonging to the section designated "Cen30". The morphological classification is SA(s)c,^[4] which indicates it is a pure spiral galaxy with relatively loosely wound arms.^[5]

NGC 4603
A Hubble Space Telescope (HST) image of NGC 4603.
Observation data (J2000 epoch)
Constellation	Centaurus
Right ascension	12h 40m 55.195s[1]
Declination	–40° 58′ 35.05″[1]
Heliocentric radial velocity	+2561[2] km/s
Distance	106.8 Mly (32.71 Mpc)[2]
Apparent magnitude (V)	12.3[3]
Characteristics
Type	SA(s)c
Size	100,000 ly (diameter)
Apparent size (V)	3′.4 × 2′.5[3]
Other designations
PGC 42510[3]

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.^[6]

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.^[7]