Proper noun
Dubhe
(astronomy) A multiple star in the constellation of Ursa Major and part of the Plough; Alpha (α) Ursae Majoris.
By visually tracing a line from Merak through Dubhe and continuing, one's eye will land on Polaris, accurately indicating true north. Source: Internet
The leading edge (defined by the stars Dubhe and Merak ) was referenced to a clock face, and the true azimuth of Polaris worked out for different latitudes. Source: Internet