Exercise:
The
four stars at the corners of the Great Square of Pegasus
are:
star |
R.A. |
declination |
α And |
00h 08m |
+29°05' |
β Peg |
23h 04m |
+28° 05' |
α Peg |
23h 05m |
+15° 12' |
γ Peg |
00h 13m |
+15° 11' |
Calculate the lengths of
the two diagonals of the Square.
It is necessary to plot the
four stars, at least approximately,
to find out which pairs form
the diagonals!
Then, to find the length of
each diagonal, use the cosine rule:
cos S1S2
= cos S1P cos S2P + sin S1P sin S2P
cos P
This gives α
And to α Peg = 20.1°
and β
Peg to γ Peg = 20.5°.
Back to "the RA-dec system".