William Herschel discovered NGC 5579 = H III-415 = h1784 on 1 May 1785 (sweep 405) and noted "eF, pL." JH made two observations and noting on sweep 72 "F; pL; the preceding of 2 [with h1785 = Nova]" and on sweep 331 "eF; L; 30 or 40"." His positions on both sweeps are good, though there is nothing at his position for h1785 = NGC 5580. But 1 min of RA due east is NGC 5590. JH claimed in the GC (and repeated by Dreyer) that NGC 5579 was missed at Birr Castle (though NGC 5589 and 5590 was observed twice). But Samuel Hunter observed the trio on 9 May 1860, describing NGC 5579 as "a pL, F neb, vgbM, with a triangle formed by 3 stars". This observation was mistakenly listed in the 1880 publication under GC 3826 (future NGC 5533).

300/350mm - 13.1" (4/10/86): faint, fairly large, slightly elongated, very diffuse, even surface brightness. NGC 5590 lies 15' E and the NGC 5567/5568 pair is 15' WSW.

900/1200mm - 48" (4/30/19): at 545x; fairly bright, fairly large, larger brighter core region, roundish with a diffuse, very irregular halo. A linear segment of a spiral arm was occasionally visible on the northeast side [knotty portion of spiral arm on the SDSS]. The initial part of two spiral arms were just visible on the south side: a low contrast spiral arm extended SSE from the central region and occasionally a second parallel "arm" about 20" to its west also extended south.

48" (5/12/18): at 488x; fairly bright, fairly large, irregular shape, contains a large brighter core that appears offset to the north side. The surface brightness of the halo was fairly low so discerning structure was difficult and the seeing was fairly poor. A long spiral arm that forms a looping arc on the south side was visible as faint, curving haze but no individual HII knots were resolved.

NGC 5579 forms a close physical pair with LEDA 214249 1.7' SSE. It appeared faint (V = 17.2), fairly small, oval 3:2 WSW-ENE, ~15"x10", low even surface brightness. A mag 13.3 star is 0.6' SW.

LEDA 2061435, situated 3' NNW of NGC 5579, appeared fairly faint (V = 15.8), round, 15", very small brighter nucleus. A mag 12.5 star is just 0.4' NW.

Notes by Steve Gottlieb