sunshinesunshine

θ = 20 microarcseconds = .02 arcsec = 9.7 x 10-8 radians When you make the approximation A/θ = B you must use the degrees that give you a lower number. So for .1 arcsec the maximum parallax distance is .1 ly. ---------------------------------------------------------------------------------------------------------------------------------------------------- No, you need to use radians not degrees. You need to use the value that give you the lower number when using the approximation. ____________________________________________________________________________________________________ 1 AU / 0.1 arcsec = 1 AU / 4.85x10-7 radians = 32.6 ly (or calculated using degrees .1 ly). Does that mean the maximum distance to a star is 33 ly?

A----earth orbital diameter in meters θ----resolution of the Hubble A/θ = B ------------------>1.4 x 10^10 (3600) / .02 = 2.52 x 10^15 m = .266 ly

Ladies first

reliable distance measurements up to 5,000 parsecs (20,000 ly) Could you show your calculations? I get a value of less than one ly.

How do you measure the distance of a 4.22 ly star using parallax using the earth's orbital diameter and Hubble (.1 arcsec)?