| b>177 Irma |
| bgcolor="#ffc0c0" colspan="2" | Orbital characteristics 1 |
| a href="/encyclopedia/Orbit" title="Orbit">Orbit type | Main belt |
| a href="/encyclopedia/Semimajor-axis" title="Semimajor axis">Semimajor axis | 2.770 AU |
| a href="/encyclopedia/Perihelion" title="Perihelion">Perihelion distance | 2.115 AU |
| a href="/encyclopedia/Aphelion" title="Aphelion">Aphelion distance | 3.426 AU |
| a href="/encyclopedia/Orbital-period" title="Orbital period">Orbital period | 4.61 years |
| a href="/encyclopedia/Inclination" title="Inclination">Inclination | 1.39° |
| a href="/encyclopedia/Eccentricity" title="Eccentricity">Eccentricity | 0.237 |
| bgcolor="#ffc0c0" colspan="2" | Physical characteristics 1 |
| a href="/encyclopedia/Diameter" title="Diameter">Diameter | 73.2 km |
| a href="/encyclopedia/Rotation-period" title="Rotation period">Rotation period | 14.208 hours |
| a href="/encyclopedia/Absolute-magnitude" title="Absolute magnitude">Abs. magnitude | 9.49 |
| a href="/encyclopedia/Albedo" title="Albedo">Albedo 4 | 0.053 |
| bgcolor="#ffc0c0" colspan="2" | History 2 |
| iscoverer | P. P. Henry, 1877 |