Francis Leavenworth discovered NGC 3140 = LM 1-166 (along with I-167 = NGC 3141) on 1 Jan 1886 with the 26" refractor at the Leander-McCormick Observatory. Although he gave a single rough position for both objects, LM 1-166 is mag 15.5 and 0.5', while LM 1-167 is mag 16.0 and 0.3' dia. His position falls very close to the pair PGC 29548 and PGC 29544.

According to Harold Corwin, Leavenworth's sketch clearly shows that NGC 3140 = PGC 29548 is the brighter galaxy to the northeast and the fainter galaxy to the southwest is NGC 3141 = PGC 29544. See Corwin's identification summaries for more.

400/500mm - 17.5" (2/22/03): slightly brighter and larger of a close pair with NGC 3140 2.4' SW. Faint, small, slightly elongated, 0.5'x0.4', stellar nucleus with direct vision. Although following NGC 3141, Leavenworth listed this object first (identical coordinates) and his description indicates it is the brighter of the pair, so the NGC numbers are reversed in right ascension. Located at the east edge of the rich cluster AGC 940.

Notes by Steve Gottlieb