C/1913 Y1 (Delavan)

Comet Delavan, formally designated as C/1913 Y1, is a hyperbolic comet discovered by astronomer Pablo T. Delavan on December 18, 1913, from the La Plata Observatory in Argentina.^[3]

C/1913 Y1 (Delavan)

Comet Delavan photographed by Gavril A. Tikhov from the Pulkovo Observatory in October 1914
Discovery
Discovered by	Pablo T. Delavan
Discovery site	La Plata Observatory
Discovery date	18 December 1913
Designations
Alternative designations	1914 V, 1913f[1]
Orbital characteristics[2]
Epoch	15 March 1914 (JD 2420206.5)
Observation arc	628 days (1.72 years)[3]
Number of observations	1006
Perihelion	1.1044 AU
Eccentricity	1.00014
Inclination	68.043°
Longitude of ascending node	60.397°
Argument of periapsis	287.436°
Last perihelion	26 October 1914
Earth MOID	0.63832 AU
Jupiter MOID	1.64685 AU
Physical characteristics[4][5]
Mean radius	1.89 km (1.17 mi)[a]
Comet total magnitude (M1)	4.8
Apparent magnitude	1.1 (1914 apparition)

The comet was last seen on September 19, 1915.^[6] It is one of 19 comets used in the original sample by Jan Oort for his hypothesis regarding the origin of long-period comets in 1950.^[7]