Text #52Cometography: A Catalog of Comets. Series: Cometography. Vol. 1 .
The only ancient account of this comet appears in the Chinese text Han shu (100). It says a “tangle star” was seen in the southwest, “at about a distance of 20 degrees to the south of the Fang [β, δ, π, and ρ Scorpii]” on -146 August 6. The apparent location in the evening sky implies a UT of August 6.5. The Chinese describe it as “the size of a double-peck measure and was of a white colour.” The comet was seen northeast of Hsin [α, σ, and τ Scorpii] on August 7 and north of Wei [ε, ζ, η, θ, ι, κ, λ, and μ Scorpii] on the 8th. Estimates of the tail length on these two dates indicate values of 10 degrees and 60 degrees, respectively. The comet was seen near the Milky Way, north of Chi [γ, δ, ε, and η Sagittarii], on August 11. The comet became smaller until it “was as large as a peach” on August 16, after an appearance of 10 days.
J. Williams (1871) gave a slightly different interpretation. For August 6, he said the comet was “in the southern part of Fang” and that “when it left Fang it was 20 degrees in length.” For August 11, he wrote that the comet “entered Chi, to the north, near the star Han.” Han was identified as ζ Ophiuchi.
Ho Peng Yoke (1962) said the comet “went out of sight in the morning”; however, very similar parabolic orbits computed by S. Kanda (1973) and I. Hasegawa (1979) indicate the comet was in the evening sky, which indicates a probably UT of August 16.5.
Hasegawa’s orbit is given below and indicates the comet reached a minimum solar elongation of 18 degrees on June 15, and its most southerly declination of -24 degrees (apparent) on August 1. The comet reached a maximum solar elongation of 110 degrees on August 20.
Full moon: July 29, August 27