177 Irma

177 Irma

Discovery
Discovered by	P. P. Henry, 1877
Discovery date	5 November 1877
Designations
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	4.61 yr (1682.5 d)
Mean anomaly	42.096°
Mean motion	0° 12^m 50.256^s / 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)
Jupiter Tisserand parameter	3.296
Physical characteristics
Mean radius	36.61±0.8 km
Rotation period	13.856 h (0.5773 d)[1][2]
Geometric albedo	0.0527±0.002
Spectral type	C
Absolute magnitude (H)	9.49

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]

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]

References

1. Yeomans, Donald K., "177 Irma", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 6 May 2016.
2. Pilcher, Frederick (April 2012), "Rotation Period Determinations for 31 Euphrosyne, 65 Cybele, 154 Bertha 177 Irma, 200 Dynamene, 724 Hapag, 880 Herba, and 1470 Carla", The Minor Planet Bulletin 39 (2), pp. 57–60, Bibcode:2012MPBu...39...57P.
3. Schmadel, Lutz D. (2012), Dictionary of Minor Planet Names (6th ed.), Springer, p. 29, ISBN 3642297188.

External links

• 177 Irma at the JPL Small-Body Database

• Discovery · Orbit diagram · Orbital elements · Physical parameters