Star S in the Big Dipper constellation (Ursa Major) has a regular variation in its apparent magnitude': The magnitude is known to be periodic with period 240, so that the magnitude at 8 = -100 is the...

Star S in the Big Dipper constellation (Ursa Major) has a regular variation in its apparent magnitude':

The magnitude is known to be periodic with period 240, so that the magnitude at 8 = -100 is the same as at 8 = 140. The m-spline y = csape (x,y, 'periodic') constructs a cubic spline whose first and second derivatives are the same at the ends osf the interval. Use it to
²L. Campbell and L. Jacchia. The Story of Varzable Stars. The BlacKiston Co., Philadelphia, 1941.

interpolate the data. Plot the data and the interpolating curve in the same figure. Estimate the magnitude at
 = 0.