William Herschel discovered NGC 4666 = H I-15 = h1420 on 22 Feb 1784 (sweep 153) and recorded "E from sp to nf, seems to contain bright places in the middle; it is not cometic, but appears to be resolvable. It resembles the two foregoing nebula [NGC 4666 and NGC 4592] but is narrower." JH logged "pB; mE; psbM; pos 45° nf or sp." and measured an accurate position.

400/500mm - 17.5" (2/28/87): very bright, edge-on 4:1 SW-NE, fairly large, 4'x1', very bright core, mottled and streaky appearance. A close trio of mag 11-13 stars lies 5' SE. Forms a pair with NGC 4668 8' SE, which follows the triple star.

Notes by Steve Gottlieb