# How to measure the distance of an object using standard candles?

Standard Candle techniques can only be used to determine the exact distance from Earth to another standard candle, right?

I mean, imagine I want to know the distance to a star A in galaxy $$\alpha$$. In galaxy $$\alpha$$, close to the star A, I notice there is a Type I Cepheid and I measure its apparent magnitude (m), I calculate the absolute magnitude (M) - using the Luminosity ($$L$$) I know -, and finally I get $$d_L$$.

So now I claim that the distance from Earth to Galaxy $$\alpha$$ is $$d_L$$?? And I can also claim that, within some error, the distance from Earth to star A is also $$d_L$$. Is this what astronomers do?

• Nov 13 '19 at 16:18