177 Irma

177 Irma is a fairly large and dark main belt asteroid. It was discovered by the French brothers Paul Henry and Prosper Henry on November 5, 1877. Paul was credited for this discovery. The meaning of the name Irma is unknown.^[3]

177 Irma

Orbital diagram
Discovery
Discovered by	P. P. Henry, 1877
Discovery date	5 November 1877
Designations
MPC designation	(177) Irma
Alternative designations	A877 VA; 1900 UB; 1900 VA;1912 HE; 1937 UA, 1962 DB
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	115.30 yr (42113 d)
Aphelion	3.4260 AU (512.52 Gm)
Perihelion	2.1110 AU (315.80 Gm)
Semi-major axis	2.7685 AU (414.16 Gm)
Eccentricity	0.23749
Orbital period (sidereal)	4.61 yr (1682.5 d)
Mean anomaly	42.096°
Mean motion	0° 12m 50.256s / day
Inclination	1.3893°
Longitude of ascending node	347.55°
Argument of perihelion	38.184°
Earth MOID	1.11401 AU (166.654 Gm)
Jupiter MOID	2.03001 AU (303.685 Gm)
TJupiter	3.296
Physical characteristics
Mean radius	36.61±0.8 km
Synodic rotation period	13.856 h (0.5773 d)[1][2]
Geometric albedo	0.0527±0.002
Spectral type	C
Absolute magnitude (H)	9.49

Photometric observations of this asteroid at the Organ Mesa Observatory in Las Cruces, New Mexico in 2011 gave a light curve with a period of 13.856 ± 0.001 hours and a brightness variation of 0.30 ± 0.03 in magnitude.^[2]