1,334. Visibility Limits

Hilchos Kiddush HaChodesh 17:16

If the arc of visibility is between the start of the 10th degree and the end of the 14th, evaluate the arc’s relationship to the first longitude and determine if the moon will be visible from the bounds that are known as visibility limits.

Hilchos Kiddush HaChodesh 17:17

These are the visibility limits: if the arc of visibility is between nine and ten degrees, or greater than ten degrees, and the first longitude is 13 degrees or higher, the moon will certainly be visible; if the arc or the first longitude is smaller than this, the moon will not be visible.