This negative photo shows the faint image of periodic comet Halley (in the circle) at the record heliocentric distance 18.82 AU (= 2,820 million km, about the distance of Uranus). ... They were cleaned to remove various sky and instrumental noise, shifted according to the predicted motion of the comet and then co-added. ... The position in the sky is less than 1 arcsec from that predicted on the basis of the comet's very well-determined orbit. ... Total exposure time: 13,500 seconds. ...