C/1891 F1 (Barnard–Denning)

For other comets discovered by Edward E. Barnard and William F. Denning, see Comet Barnard and Comet Denning.

Comet Barnard–Denning, also known as C/1891 F1 by its modern nomenclature, is a parabolic comet that was observed through telescopes between March and July 1891. It was discovered by American astronomer, Edward Emerson Barnard, and British astronomer, William Frederick Denning.

C/1891 F1 (Barnard–Denning)

Comet Barnard–Denning as sketched by William F. Denning on 4 April 1891, alongside a passing meteor.
Discovery[1]
Discovered by	Edward E. Barnard William F. Denning
Discovery site	Lick Observatory, California Bristol, England
Discovery date	30 March 1891
Designations
Alternative designations	1891a[2] 1891 I
Orbital characteristics[3]
Epoch	28 April 1891 (JD 2411850.5)
Observation arc	101 days
Number of observations	110
Perihelion	0.398 AU
Eccentricity	~1.000
Inclination	120.512°
Longitude of ascending node	195.454°
Argument of periapsis	178.750°
Last perihelion	28 April 1891
Physical characteristics[4]
Comet total magnitude (M1)	8.8
Comet nuclear magnitude (M2)	9.5
Apparent magnitude	8.0 (1891 apparition)

Discovery and observations

Edward Emerson Barnard was in the Lick Observatory looking for new comets in the northwestern sky when he spotted this comet on the early morning of 30 March 1891, describing it as a "small, faint nebulous object" within the constellation Cetus.^[a] William Frederick Denning independently discovered the comet approximately 17 hours after Barnard did.^[1]

John M. Thome and his colleague, Richard H. Tucker were the last astronomers to have seen Comet Barnard–Denning,^[5] where they observed the comet from the Cordoba Observatory on 9 July 1891 as a faint object within the constellation Vela.^[b]

Orbit

The first orbital calculations for C/1891 F1 were written by Adolf Berberich, using positions recorded between 31 March and 2 April 1891.^[4] The comet reached perihelion on 28 April 1891.^[3] Due to the very few follow-up observations conducted, its retrograde trajectory was not fully determined, however it is assumed to be parabolic.^[6][7]