Does the time for Maghrib prayer extend from 7:49 to 9:18 based on the mosque's timing and the mentioned book?

The time for the Maghrib prayer begins at sunset and ends with the disappearance of the red twilight. Performing it at the beginning of its time is better. The determination of prayer times relies on the legal signs, and on reliable calendars approved by trustworthy scholars, which are to be followed unless they contradict the legal signs. As for unknown calendars, they can be used for approximation but should not be relied upon completely.