The NASA Infrared Telescope Facility Comet Halley monitoring program. II - Postperihelion results

Postperihelion 1-20-micron magnitudes of Comet Halley obtained at the NASA Infrared Telescope Facility are presented. These magnitudes complement the preperihelion magnitudes published earlier by Tokunaga et al.(1986). The time period covered in this program was March 1986 through June 1987. While no systematic near-infrared color change was found during the preperihelion passage, a distinct J-H, H-K color change occurred during the postperihelion passage after July 1986. This indicates that there was a change in either the composition or particle size of the cometary dust, or both.