C/1993 Y1 (McNaught–Russell)

"Comet McNaught–Russell" redirects here. For other comets also co-discovered by R. H. McNaught and K. S. Russell, see Comet McNaught (disambiguation) § Others.

C/1993 Y1 (McNaught–Russell)

Discovery
Discovered by	Robert H. McNaught Kenneth S. Russell
Discovery site	Siding Spring Observatory
Discovery date	17 December 1993
Designations
MPC designation	C/1993 Y1 C/574 G1
Alternative designations	1994 XI 1993v
Orbital characteristics
Epoch	28 April 1994 (JD 2449470.5)
Observation arc	265 days
Number of observations	377
Aphelion	270 AU (inbound) 240 AU (outbound)
Perihelion	0.8676 AU
Eccentricity	0.9932
Orbital period	1,600 years (inbound) 1,300 years (outbound) 1,430 ± 30 a
Inclination	51.586°
Longitude of ascending node	166.359°
Argument of periapsis	353.468°
Last perihelion	31 March 1994
Next perihelion	~3300
TJupiter	0.755
Earth MOID	0.1212 AU
Jupiter MOID	2.6212 AU
Physical characteristics
Comet total magnitude (M1)	12.3
Comet nuclear magnitude (M2)	16.9
Apparent magnitude	6.5 (1994 apparition)

Comet McNaught–Russell, formally designated as C/1993 Y1, is a long-period comet that reached a maximum magnitude of 6.5 (just below naked eye level) in early 1994. It was discovered by Robert H. McNaught and Kenneth S. Russell using the U.K. Schmidt Telescope in Australia. McNaught and Russell worked at Siding Spring Observatory and together discovered five comets between 1991 and 1995.

Orbit

Its orbital period was found to be very high – initially estimated at over 1400 years.

Historical records

C/574 G1

Discovery
Discovery site	China
Discovery date	4 April 574
Orbital characteristics
Epoch	25 March 574 (JD 1930794.5)
Observation arc	49 days
Number of observations	3
Perihelion	0.730 AU
Orbital period	1,430 ± 30 years
Inclination	54°
Longitude of ascending node	155°
Argument of periapsis	342°
Last perihelion	25 March 574 31 March 1994
Next perihelion	~3300

It was noted by Francois Colas (Paris observatory) and Ichiro Hasegawa that the path of McNaught–Russell coincided with that of comet C/574 G1, which was recorded in AD 574 over a period from April 4 to May 23 by observers in China. This would give the comet a period of 1430 ± 30 years and so making it the longest period comet to be seen on two separate returns. Since the comet was not observed to approach any planets, its orbit should remain largely unchanged on its next return. This would place its next approach to the inner Solar System around 3300.