84P/Giclas

84P/Giclas is a Jupiter-family comet with a 6.69-year orbit around the Sun. It is the only comet discovered by American astronomer, Henry L. Giclas.

Observational history

1931 apparition

It was announced in 1995 that Clyde W. Tombaugh had observed a previously unknown comet for three nights in September 1931. Designated as D/1931 R1, it was later confirmed to be an earlier apparition of 84P/Giclas upon reconstructing its orbit using non-gravitational accelerations in a 1996 study by Grzegorz Sitarski[pl].

1979 apparition

The comet was discovered by Henry L. Giclas from the Lowell Observatory on 8 September 1978. At the time it was a diffuse 15th-magnitude object within the constellation Cetus. He confirmed his discovery about two days later, where Brian G. Marsden soon determined that it follows a 6.74-year periodic orbit around the Sun. Throughout its 1978–1979 apparition, it remained mostly a photographic object.

Follow-up observations

During the 2020 apparition, it was not more than 60 degrees from the Sun until September 2020. On 11 June 2033, the comet will pass 0.0387 AU (5.79 million km; 3.60 million mi) from the asteroid 4 Vesta.

Physical characteristics

Based on observations by the Hubble Space Telescope in 1999–2000, the nucleus of the comet has a radius of 0.90±0.05 km, assuming a geometric albedo of 0.04.

Notes

External links

• at the JPL Small-Body Database· · · · ·
• at Gary W. Kronk's Cometography
• at Seiichi Yoshida's website
• at Syuichi Nakano's website