William Herschel discovered NGC 4535 = H II-500 on 28 Dec 1785 (sweep 498) and described "very large, easily resolvable. I see a few of the largest stars in it." In his 1814 PT paper, WH hypothesized this object may be a cluster of stars mixed with nebulosity or a cluster seen at great distance which contains no nebulosity. JH did not make any observations, though d'Arrest made four observations and described it as up to 5 or 6' in size. He also noted the mag 15 star (called mag 17) just 48" preceding the nucleus.

The nickname "Lost Galaxy" is from Leland S. Copeland's February 1955 S&T article "Adventuring in the Virgo Cloud". In his article, Copeland described a star hop through the Virgo Cluster using his 8" Cave reflector. He states, "North of the Diamond is a very dim spiral, here called the Lost Galaxy, NGC 4535." Leland was probably referring to NGC4535's difficulty to locate due to its low surface brightness. The a caption of a photograph states that NGC 4535's "delicate structure shows only on long exposure photographs".

400/500mm - 17.5" (4/18/87): bright, fairly large, very small bright core, elongated SSW-NNE, about 5.5'x4.0'. Appears slightly darker on both sides of core (this is a gap between the spiral arms). A mag 13.5 star is superimposed on the north side 1.0' from the center and a similar star is at the south end of the halo 2.2' from center. A faint mag 14.5 star is just 48" SW of the core. NGC 4526 lies 30' SSW.

600/800mm - 24" (5/24/20): at 260x; bright, large, face-on spiral with a low contrast "S" shape, ~5'x4' N-S. Strongly concentrated with a small bright core elongated N-S and an intense quasi-stellar nucleus. A mag 14.5 star is superimposed 0.8' SW of center. The northern arm was very subtle; it curved clockwise to the west, passing close to a mag 13.5 star 1' N of center. A faint 15" knot, [HK83] #157, was at the end of this arm, 1' NW of center. A low contrast arm on the south side curled towards the east and north. A mag 15 star is 1.2' S of center (just south of the arm) and a mag 14 star is 2.2' S of center at the edge of the outer halo.

900/1200mm - 48" (4/4/13): NGC 4535 is a gorgeous face-on Sc spiral with two, long, very prominent arms extending from a small, very bright central region. The small, very bright core is elongated SSW-NNE and punctuated by an intense, stellar nucleus. The two main arms are clearly attached right at opposite ends of the core. At the northeast end, a beautiful thin arm winds clockwise to the west with a mag 13.5 star pinned on the outer north edge. The arm contains NGC 4535:[HK83] #157 (several additional entries including #141/145 are in Hodge & Kennicutt's "Atlas of HII regions in 125 galaxies"), a small, bright, 15" knot and then dims as it wraps to the south. A mag 14.5 star is situated midway between the nucleus and southern end of this arm [47" SW of the nucleus].

The second main arm is attached at the southwest end of the core and curves clockwise to the southeast, where the arm brightens in an elongated 30" patch (#51/52/72/78), which is symmetrically positioned opposite #157. A fainter arm segment, extending WNW to ESE is visible on the south side, containing #84/90, a small, fairly faint 12" patch, located 1.5' SSE of center. This knot forms the vertex of a flat isosceles triangle with a mag 15 star 0.5' NW and a mag 14 star 0.7' S. The arms are etched on the slightly fainter and larger background glow of the disc, which extends 5.5'x4.0' in a N-S orientation.

Notes by Steve Gottlieb