Albert Marth discovered NGC 6504 = m 358 on 27 Jul 1864 and noted "F, vmE, sbM, 2' l." His position is accurate.

300/350mm - 13.1" (6/18/85): fairly faint, small, pretty edge-on WNW-ESE, bright core, thin faint extensions. Located 22' SW of a mag 7 star.

400/500mm - 17.5" (8/1/89): moderately bright, edge-on E-W, sharp concentration, almost stellar nucleus. Situated between a mag 11 star 1.9' N and a mag 10.5 star 2.1' SE of center.

600/800mm - 24" (6/21/20): at 375x; fairly bright, large, very thin edge-on ~8:1 E-W, ~2.0'x0.25'. Contains a bright very elongated core and a nearly stellar nucleus. A mag 11 star is 2' SE and a slightly fainter star is 2' N. Located 20' SW of mag 6.9 HD 163948.

NGC 6504, located 28' NE, appeared fairly faint, moderately large, very elongated 3:1 NW-SE, 1.0'x0.3'. Unusual bowed or banana shape, concave outwards towards the west. The core seems offset towards the northwest side of the central region. Located in a rich star field with a mag 10.5 star 1.3' W.

Notes by Steve Gottlieb