Reading the Position: Taurus 12 Degrees 26 Minutes, at a Boundary

The atlas records this star at Taurus 12 degrees 26 minutes, projected from Andromeda, and notes that it stands near the border with Perseus.

That border is more definite than it sounds and more recent. Constellation boundaries were not fixed until the International Astronomical Union adopted Eugene Delporte's scheme in 1930, drawing them as arcs of right ascension and declination for the epoch 1875. Before that a star near a boundary genuinely belonged to whichever figure an atlas maker chose to draw it into, and old lists disagree. So a star described as being on the edge of Andromeda and Perseus is being described by a convention less than a century old, laid over names many centuries older.

The zodiacal longitude is a separate projection again. Neither Andromeda nor Perseus touches the ecliptic; both lie well north of it, and the sign given here is where a line dropped from the star to the ecliptic falls, not a region of sky the star occupies.

Precession dates the figure. A fixed star advances about fifty seconds of arc a year, one degree in roughly seventy two years, so taking the recorded value for epoch 2000 this star entered Taurus around the beginning of the twelfth century and will reach Gemini in something over twelve hundred years.