Large aperture O I 6300 Å observations of comet hyakutake: Implications for the photochemistry of OH and O I production in comet Hale-Bopp

In previous work (Morgenthaler et al. and Glinski et al.), we proposed a revision to the standard OH photo-chemistry of van Dishoeck & Dalgarno in order to explain the anomalously bright [O I] 6300 Å emission observed by several instruments in comet C/1995 O1 (Hale-Bopp). In order to test the validity of revisions to the OH photo-chemistry, we present wide-field Fabry-Pérot [O I] 6300 Å observations of comet C/1996 B2 (Hyakutake) and review similar observations recorded for 1P/ Halley and 1989 c 1 (Austin). Conventional long-slit spectroscopic observations of several comets in [O I] are also reviewed. The bulk of the evidence suggests that the OH photochemical rates of van Dishoeck & Dalgarno are, on the whole, correct and that the bright [O I] emission observed in Hale-Bopp, particularly at cometocentric distances beyond ∼3 × 10⁴ km, was unique to that comet, or possibly any comet with such a large production rate.