The Iowa Robotic Observatory (IRO) located in the Sonoran desert near Sonoita, Arizona, was used for an optical search for small comets in the vicinity of Earth during the period October 1998 through May 1999. The previous reports of detection of the small comets with an optical telescope were based on the search with the Spacewatch Telescope during November 1987, January 1988, and April 1988. The searches with both of these telescopes required that their fields of view be moved in a special manner across the celestial sphere in order to maximize the dwell times of the comet images on a small set of pixels of the telescopes' array detectors. There were sightings of nine small comets in the set of 1500 usable images which were gained with the IRO. The possibility that these events were spurious owing to random fluctuations of the responses in the sensors was eliminated in two different ways. The first method was the use of a shutter to provide either two or three trails for the same small comet. In the two-trail mode, no events were seen with three trails, and for the three-trail mode, no events were seen with two trails. The second assurance that the trails were not due to noise was provided by a rigorous determination of the signals S and signal-to-noise ratios (S/N) in the trails due to random statistical fluctuations, or random trails, and the subsequent comparison with these parameters for the small-comet sightings. The diameter of the primary mirror of the IRO is significantly smaller than that of the Spacewatch Telescope, and thus the uncertainties in the number densities of the small comets are greater with the IRO. However, within a factor of 2 or 3, the average number densities of small comets detected with the IRO are similar to those observed previously with the Spacewatch Telescope, that is, about 10-18/m3. ¿ 2001 American Geophysical Union