C/1907 G1 (Grigg–Mellish)

Comet Grigg-Mellish photographed by Edward Emerson Barnard on 13 April 1907
Discovery
Discovered by	John E. Mellish John Grigg
Discovery date	8 April 1907
Designations
Alternative designations	1907b[1] 1907 II
Orbital characteristics[2]
Epoch	18 April 1907 (JD 2417683.5)
Number of observations	4
Aphelion	123.9 AU
Perihelion	0.924 AU
Semi-major axis	62.43 AU
Eccentricity	0.985205
Orbital period	~490 years
Inclination	109.95°
Longitude of ascending node	190.47°
Argument of periapsis	328.60°
Last perihelion	27 March 1907
Next perihelion	~2400
TJupiter	-0.322
Earth MOID	0.003 AU
Jupiter MOID	1.351 AU

C/1907 G1 (Grigg–Mellish) is a long-period comet discovered independently by John Grigg and John E. Mellish in April 1907. The comet has been identified as the parent body of the delta Pavonids meteor shower.

John Grigg, in New Zealand, discovered a nebulous object near the star α Cae on 8 April 1907, however the discovery wasn't communicated quickly enough for observers in the southern hemisphere to confirm the discovery.^[3] The comet was found independently by amateur astronomer John E. Mellish, from Madison, Wisconsin, on 14 April. The comet had an apparent magnitude of 11 upon discovery.^[4] The comet was also spotted by Edward Emerson Barnard in a photographic plate exposed on 13 April while he was searching for comet C/1907 E1 (Giacobini). The comet formed a trail 13.6 arcminutes long during the one hour the plate was exposed.^[5] The comet was reported to have a coma two arcminutes across and a broad tail 8 arcminutes long on 16 April. The comet faded rapidly and it was difficult to measure with the 36-inch telescope of Lick Observatory on 7 May.^[6]

The comet was found to have a similar orbit to comet C/1742 C1,^[7] however comet Grigg–Mellish is intrinsically fainter than that comet. The comet's orbit passes very close to Earth, at a distance of 0.003 AU (0.45 million km; 0.28 million mi); Earth passes that point on 30 March. Due to the small minimum orbit intersection distance, it was suggested to be a source of meteors with a radiant point at R.A. = 20.63^h , DEC = –60.4° and a speed of Vg = 59.0 km/s.^[8]

Comet Grigg–Mellish has been identified as the parent body of the delta Pavonids meteor shower. The shower has a zenithal hourly rate (ZHR) of 5 meteors per hour and peaks at March 31. An outburst was observed in 2019. The orbit of the meteors indicates that comet has an orbital period of 447 ± 80 years.^[8]

• C/1907 G1 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters