During 18 days the Sun remains in the constellation of Ophiuchus. It enters November 30th and it leaves December 17th. In the following graph you can see the displacement of the Sun on Ophiuchus.
The calendar of Ophiuchus transferred to civil or gregorian calendar that we have at the moment would be as it follows:
O P H I U C H U S
The calendar is formed therefore by 13 months. The months that form it correspond to the constellations in which the Sun during the year crosses them. The other months are the following ones:
Masm(Last update 10.17.2003)