NGC 6603 (also ESO 590-SC17, Melotte 197, Collinder 374 and OCL 36) is a magnitude +11.4 open star cluster located 9,400 light-years away in the constellation Sagittarius. The cluster consists of about 30 stars in a field of about 5 arc minutes in diameter, and situated within the brightest part of star cloud Messier 24.
The cluster was discovered by British astronomer John Herschel using a 47.5 cm (18.7 inch) f/13 speculum reflecting telescope at Windsor Road, Slough, on the 15th July 1830.
Right Ascension 18h 18m 24.0s, Declination -18° 24' 24"