Francis Leavenworth discovered NGC 3520 = LM 2-431 in 1886 with the 26" refractor at Leander McCormick and reported "mag 15.3, 0.4' dia, iR, gpmbM, sev vF st inv." Just 2' north of his position is a 1' group of four stars (brightest two are mag 13 and 14.5) and originally Harold Corwin identified this group as NGC 3520. He now feels a more likely match based on the description is ESO 570-004 = PGC 33648, an interacting triple or quadruple system located 1.6 min of RA east and 5' south of Leavenworth's position. ESO misidentified ESO 570-003 as NGC 3520. This edge-on galaxy is situated 44 sec of RA east of Leavenworth's position and 19' south. RNGC classifies the number as nonexistent. See Corwin's NGC identification notes.

600/800mm - 24" (2/22/14): at 260x appeared faint to fairly faint, fairly small, oval 4:3 WSW-ENE, 20"x15", fairly low surface brightness. An extremely low surface brightness halo was not seen. This is a close double system [9" between centers] but was not resolved at 260x. The NGC identification is uncertain due to a poor position.

Notes by Steve Gottlieb