William Herschel discovered NGC 6140 = H III-740 on 3 Jun 1788 (only nebula in sweep 845) and logged "cF, pL, iE." There is nothing at his position but 95 sec of RA following is UGC 10359. Dreyer noted this error in his 1912 Scientific Papers.

400/500mm - 17.5" (7/9/88): moderately bright, moderately large, elongated ~E-W, broadly concentrated halo, very faint extensions. A mag 12 star lies 2.2' NW. Bracketed by three mag 15 stars 1.4' SE, 1.6' NNE and 1.9' SW of center.

600/800mm - 24" (7/22/14): fairly bright, moderately large, oval 3:2 WSW-ENE, broad concentration. Often a thin brighter "bar" oriented WSW-ENE stands out. It appears offset from center as the south portion of the halo is very weak. At 375x, a narrow spiral arm oriented E-W is occasionally visible just south of the bar, and it extends slightly further east than the brighter central region. A mag 11.5 star lies 2.3' NW and several mag 15 stars are nearby.

Notes by Steve Gottlieb