William Herschel discovered NGC 5506 = H II-687 = h1757 on 15 Apr 1787 (sweep 730) and recorded "pB, cL, mE nearly in the parallel." His RA is 9 tsec too large and dec 1' south (typical error). JH measured an accurate position.

400/500mm - 17.5" (4/4/92): moderately bright, moderately large, edge-on 5:1 E-W, 3.0'x0.6', broad concentration. Located 11' NE of mag 7.9 SAO 139790. Forms a pair with NGC 5507 3.7' NNE. This is a Seyfert and Markarian galaxy.

Notes by Steve Gottlieb