(a) Selection of 10 of the delay-Doppler images from 2010 October 25 to 31, showing two sides of the Hartley nucleus. The images are ordered by rotation phase, with the upper five images spanning phases 347 9–42 6 and the lower five spanning 131 0–157 6. (Our convention defines zero phase as when the nucleus is broadside and with the larger lobe approaching.) Delay is the vertical axis and Doppler is the horizontal axis. Delay and Doppler increase downward and leftward, respectively, so the rotation sense is clockwise. Each pixel measures 0.5 μs × 0.18 Hz. (b) Delay-Doppler image (upper left), best-fit model delay-Doppler image (lower left), and corresponding plane-of-sky model figure (right) for the third Hartley imaging epoch in (a); the rotation phase is 16 9. (c) Similar to (b), but from Arecibo radar observations of Comet 8P/Tuttle on 2008 January 3; the rotation phase is 12 9.