Another new planetary system imaged

In article ,
John Polasek wrote:

snip

I revise it to LY*mas = 3200. So for AlphaC it's mas = 3200/4 = 800
mas.

You've got the idea, although 3260 is a better figure for the constant.
According to Simbad, the Hipparcos parallax for Proxima Centauri is 772
+/- 2 mas; 3260/772 = 4.22 LY. For Rigil Kent it's 742 +/- 1 mas = 4.39
LY.

Note that you can only use this method with precision when the angle is
small, making the simple inverse function a good approximation to the
cosecant.

1 pc = csc(0°0'1") AU ~= 206265 AU.

3600*180/pi ~= 206265.

When calculated to high precision, the above two figures differ by about
one part in 250 billion.

--
Odysseus