How do you find the angle in arc seconds when observing a star?

This is a follow up question of parallax technique????? But i understand trig and that a closer star will move more relative to the background stars and now i just need to know how to find the angle?How do you find the angle in arc seconds when observing a star?Take two photos separated by an interval of exactly six months (opposite ends of Earth's orbit, like Jan4 %26amp; July6 that are 299.2 G metres) of the stars with the other stars that are far beyond. The linear distance on the photo plate indicates the arc (angle) distance. Ordinarily or by using blinking method measure the difference in the chosen star's position. It gives the double of parallax angle. The earth's position at various calender dates (6 months apart) lead to different parallax angles. But the variation is insignificant because Earth's orbit sufficiently less circular.How do you find the angle in arc seconds when observing a star?I am sorry for the error that crept in.

For "299.2 G metres" read "319.2464 G metres".

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How do you find the angle in arc seconds when observing a star?Basically you observe the star in January, measure its position very carefully, and then do the same thing in July. The difference between the two measurements is twice the parallax angle.



That is a bit oversimplified; you also have to correct the measured positions for aberration of starlight.How do you find the angle in arc seconds when observing a star?
Draw the diagram.