C/1907 L2 (Daniel)

Daniel's Comet, formally known as C/1907 L2, is a non-periodic comet that became visible in the naked eye in 1907. It was the first of three comets discovered by American astronomer, Zaccheus Daniel.

C/1907 L2 (Daniel)

Daniel's Comet photographed by Max Wolf on 4 August 1907[1]
Discovery
Discovered by	Zaccheus Daniel
Discovery site	Princeton, New Jersey
Discovery date	10 June 1907
Designations
Alternative designations	1907 IV, 1907d[2]
Orbital characteristics[3]
Epoch	27 September 1907 (JD 2417845.5)
Observation arc	344 days
Number of observations	173
Aphelion	830.60 AU
Perihelion	0.512 AU
Semi-major axis	415.55 AU
Eccentricity	0.99877
Orbital period	~8,470 years (inbound) ~5,220 years (outbound)
Inclination	8.958°
Longitude of ascending node	144.27°
Argument of periapsis	294.47°
Last perihelion	4 September 1907
TJupiter	0.889
Earth MOID	0.058 AU
Jupiter MOID	0.417 AU
Physical characteristics[4][5]
Mean radius	2.62 km (1.63 mi)[a]
Comet total magnitude (M1)	3.7
Comet nuclear magnitude (M2)	7.2
Apparent magnitude	2.6 (1907 apparition)

Discovery and observations

The comet was discovered by Zaccheus Daniel using a 15 cm (5.9 in) comet-seeker on the dawn of 10 June 1907, however its nature as a comet wasn't confirmed until two days later by William Robert Brooks.^[5] At the time, the object was located within the constellation Pisces.^[b]

The comet rapidly brightened as it slowly approached the Earth, and was closest at 0.757 AU (113.2 million km) on 2 August 1907.^[5] Edward E. Barnard made a series of photographic observations of the comet between 11 July and 8 September 1907, where he described the comet being visible to the naked eye for two months.^[6] At the same time, Edward C. Pickering also made several photographic observations between 12 July and 4 August 1907.^[7] J. Charles Duncan noted that the comet had reached magnitude 3.0 on 24 July 1907.^[8] Across the Atlantic, Max Wolf made extensive observations of the comet until 27 August.^[1][9]

It was last observed from the Chamberlin Observatory in Denver, Colorado, on the early morning of 30 June 1908.^[5]