Hubble's law has been well-know for close to a century now. It is written as

$v = H_0 d$

where the Hubble constant $H_0$ is the constant of proportionality between recession speed $v$ and distance $d$ in the expanding Universe.

The expression for the Hubble constant itself is normally written as

$H_0 = 100 h km s^{−1} Mpc^{−1}$

where $h$ is the dimensionless parameter expressing of ignorance. How is this "little h" measured?

Do astronomers measure the Hubble constant (using Cepheid distances, Type Ia Supernovae, etc.) and then calculate $h$?

Supposedly the value agreed upon today is around $h\approx0.7$. Give or take.

Hubble's law has been well-know for close to a century now. It is written as

$v = H_0 d$

where the Hubble constant $H_0$ is the constant of proportionality between recession speed $v$ and distance $d$ in the expanding Universe.

The expression for the Hubble constant itself is normally written as

$H_0 = 100\,h\,{\rm km}\,{\rm s}^{−1}\,{\rm Mpc}^{−1}$

where $h$ is the dimensionless parameter expressing of ignorance. How is this "little h" measured?

Do astronomers measure the Hubble constant (using Cepheid distances, Type Ia Supernovae, etc.) and then calculate $h$?

Supposedly the value agreed upon today is around $h\approx0.7$. Give or take.