William Herschel discovered NGC 4423 = H II-145 = h1266 on 13 Apr 1784 (sweep 191) and noted "eF, E." His position is 28 sec of RA east of UGC 7556. JH logged "vF; vS; E" and measured an accurate position.

400/500mm - 17.5" (4/21/90): faint, moderately large, very elongated 4:1 SSW-NNE, low even surface brightness. NGC 4430/NGC 4432 pair lies 25' NNE.

Notes by Steve Gottlieb