154 Bertha

154 Bertha is a main-belt asteroid. It was discovered by the French brothers Paul Henry and Prosper Henry on 4 November 1875, but the credit for the discovery was given to Prosper. It is probably named after Berthe Martin-Flammarion, sister of the astronomer Camille Flammarion.^[8]

154 Bertha

Discovery[1]
Discovered by	P. M. Henry
Discovery date	4 November 1875
Designations
MPC designation	(154) Bertha
Pronunciation	/ˈbɜːrθə/[2]
Alternative designations	A875 VD
Minor planet category	Main belt
Orbital characteristics[3][4]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	130.75 yr (47758 d)
Aphelion	3.44 AU (515.21 Gm)
Perihelion	2.95 AU (441.30 Gm)
Semi-major axis	3.20 AU (478.26 Gm)
Eccentricity	0.077261
Orbital period (sidereal)	5.72 years (2,087.9 d)
Average orbital speed	16.63 km/s
Mean anomaly	125.046°
Mean motion	0° 10m 20.734s / day
Inclination	20.9724°
Longitude of ascending node	36.7441°
Argument of perihelion	159.722°
Earth MOID	1.95 AU (291.94 Gm)
Jupiter MOID	1.53 AU (229.03 Gm)
TJupiter	3.087
Physical characteristics
Dimensions	184.93±3.6 km[3] 186.85±1.83 km[5]
Mass	(9.19±5.20)×1018 kg[5]
Mean density	2.69±1.52 g/cm3[5]
Equatorial surface gravity	0.0517 m/s²
Equatorial escape velocity	0.0978 km/s
Synodic rotation period	25.224 h (1.0510 d)[3][6]
Geometric albedo	0.0480±0.002[3] 0.0483 ± 0.0107[7]
Temperature	~156 K
Spectral type	C[7]
Absolute magnitude (H)	7.58,[3] 7.530[7]

Observations performed at the Palmer Divide Observatory in Colorado Springs, Colorado in during 2007 produced a light curve with a period of 22.30 ± 0.03 hours and a brightness range of 0.10 ± 0.02 in magnitude. A 1998 measurement gave a value of 27.6 hours, which doesn't fit the PDO data.^[9] In 2011, observations from the Organ Mesa Observatory in Las Cruces, New Mexico were used to determine a rotation period of 25.224 ± 0.002 hours with a brightness variability of 0.10 ± 0.01 magnitude, ruling out previous studies.^[6]

This is classified as a C-type asteroid^[7] and it has an estimated diameter of about 187 km.^[5]