C/1921 H1 (Dubiago)

Dubiago's Comet, formally known as C/1921 H1 by its modern nomenclature, is a faint Halley-type comet that completes an orbit around the Sun once every 61–79 years.^[5] It was predicted to return in 1982, but it was not observed. It will next return to the inner Solar System by 2041.^[4]

C/1921 H1 (Dubiago)

Discovery[1]
Discovered by	Alexander Dubyago
Discovery site	Kazan Observatory
Discovery date	24 April 1921
Designations
Alternative designations	1921c[2] 1921 I
Orbital characteristics[3]
Epoch	21 May 1921 (JD 2422830.5)
Observation arc	40 days
Number of observations	27
Aphelion	33.088 AU
Perihelion	1.1161 AU
Semi-major axis	17.102 AU
Eccentricity	0.93474
Orbital period	70.73 years
Inclination	22.345°
Longitude of ascending node	67.127°
Argument of periapsis	97.481°
Last perihelion	5 May 1921 (last observation) 9 August 1982[4] (calculated)
Next perihelion	25 June 2041[4]
TJupiter	1.496
Earth MOID	0.384 AU
Jupiter MOID	0.817 AU
Physical characteristics[5]
Apparent magnitude	10.5 (1921 apparition)

Discovery and observations

The comet was first spotted from the Kazan Observatory on the evening of 24 April 1921.^[5] Initially, the discovery of the comet was incorrectly credited to Dmitri Dubyago, but the attribution was later clarified to Alexander Dubyago a year later.^[6][7]