HD 66428 b is a long-period jovian exoplanet located approximately 174 light-years away in the constellation of Monoceros. It has a minimum mass of 2.82 M_J and takes 1973 days or 5.402 years to orbit around its solar-type star HD 66428. The average distance is 3.18 AU, about half the distance between Mars and Jupiter. This planet is a so-called eccentric Jupiter with an orbital eccentricity of 0.465. At periastron, the distance is 1.70 AU and at apastron, the distance is 4.66 AU.^[1] In 2022, the inclination and true mass of HD 66428 b were measured via astrometry.^[2]

HD 66428 b

Discovery
Discovered by	Butler et al.[1]
Discovery site	California
Discovery date	July 15, 2006
Detection method	Radial velocity
Orbital characteristics[2]
Semi-major axis	3.395+0.141 −0.157 AU
Eccentricity	0.471±0.012
Orbital period (sidereal)	6.214+0.015 −0.016 yr
Inclination	16.639°+10.121° −2.959°
Longitude of ascending node	299.391°+8.486° −8.219°
Time of periastron	2450057.763+16.562 −18.431
Argument of periastron	185.689°+1.688° −1.596°
Semi-amplitude	54.441+1.035 −1.167 m/s
Star	HD 66428
Physical characteristics[2]
Mass	10.946+2.442 −3.845 MJ