Why were star positions in Ptolemy’s Almagest often described by their places in constellation figures?

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Astronomical map Star trails over banksia trees, in Gippsland, Vic., Austl. The south celestial pole, located in the constellation Octans, is at the centre of the trails.

In the Almagest, Ptolemy described most stars by their positions within constellation figures because he was placing them within established, well-known celestial imagery. This practice indicates that star maps, likely in the form of globes, existed prior to his work.1

While Ptolemy did include ecliptic coordinates and magnitude classes for 1,022 stars, he only cited about a dozen stars by specific names. For the remaining stars, his descriptive method—such as identifying a star as being on the "tail" of a bird—served as a primary way to locate them within the recognized figures. Many modern star names, such as Deneb, are simply translations of these original descriptive positions.21