"Sixty days after the winter solstice corresponds by astronomical definition to February 20.

On that date in 1250 B.C. Arcturus rose before sunset, was two and one-half degrees above the horizon at sunset, and seven degrees above the horizon by thirty-tree minutes after sunset, when it could shine through the fading glow of the day.

On the same date in 700 B.C., Arcturus did not rise until after sunset and did not attain a seven-degree elevation above the horizon until one hour and twelve minutes after sunset. By then it was totally dark; the facts of 700 B.C. simply do not seem to fit the circumstances of acronychal rising as defined in the passage of Hesiod."

"Curiously enough ... phenomena Hesiod mentions are ... more appropriate to a date of 1250 than to Hesiod's date of 700 B.C. There is a rather technical temporal formula given at Works and Days 564-566:

'When Zeus, after the turn of the (winter) solstice, has completed sixty wintry days, that's when the sign-star Arcturus leaves the cold stream of Ocean and first rises acronychally in splendor'.

The occurrence of the solstices was not determinable by any exact stellar apparition but was to be found roughly by the use of a gnomon. The apparition of Arcturus confirms that the solstice was sixty days past. Its rising is one of the few sure signposts of the year. Arcturus is the fifth brightest star (zero magnitude) visible in the northern latitudes. If it is not obscured by haze or a high horizon, it will become visible within a half-hour after sunset." (Worthen)