We have constructed a synthetic spectrum of the 2.5 micron C2H C2H bands and compared them with diminutive structures in the near-infrared spectra of Comets P/Halley and West (1976 VI). We found that the Q branches of the C2H C2H bands coincide with two small emission peaks in the spectra of the comets. We undertook Monte Carlo simulations using observed emission intensities of C2 C2 and possibly C2H C2H in Comet P/Halley in order to derive a lifetime range of C2H C2H and a production rate at the time of observations of P/Halley. We obtained a C2H C2H production rate of 1×1027sec−1 1×1027sec−1 for P/Halley on December 20, 1985, assuming the 2.5 micron features are due to C2H C2H . We derived a very short lifetime (<100 seconds) of C2H C2H at 1AU heliocentric distance, assuming that the only parent molecule for C2H C2H and C2 C2 is C2H C2H . Using this short lifetime we were unable to fit our C2 C2 distribution model to C2 C2 distribution curves observed by O'Dell et al.(1988), because our curve shows a steep slope compared with the observed one. We conclude that there must be significant additional source(s) for C2H C2H and C2 C2 other than C2H2 C2H2 .

We examined a total of 166 images of 3.5 μm H3+ emission in the auroral regions of Jupiter observed with the Protocam on IRTF in 1991 and 1992, and found that 30 images contain a clearly isolated small emission patch in the vicinity of the northern auroral regions. Two different time sequences of the images show the small patches at the dusk limb in the range of System III longitudes from 270° through 0° to 90°. The small patches in one sequence of the images, which were taken at 10 phase between 240° and 260°, may be related to the 10 flux tube, similarly suggested by Connerney et al. (1993). However, the small patches in the other sequence are separated from Io as much as 80° in longitude. The positions of the small patches in both sequences are deviated equatorward from the 10 footprint oval by 5° - 8° latitude in the longitudinal range of 270° - 360°. A significant modification is required in current Jovian magnetic field models near the Jupiter's surface if the small patches are produced at the foot of the 10 flux tube.