Alpheratz (α Andromedae) is a spectroscopic double star in the constellation Andromeda. The system is about 100 light-years (ly) away and has an apparent magnitude of 2.06 mag.
Alpheratz (sometimes referred to as Sirrah) is at the northeast end of Pegasus Square (Autumn Square). In some older star charts, Sirrah is therefore not counted to the constellation Andromeda, but to Pegasus and referred to as δ Pegasi (Delta Pegasi).
However, since today’s constellation boundaries were defined in 1930, the term δ Pegasi is no longer in use.
| Alpheratz | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 08m 23.26s |
| Declination | +29° 05′ 25.6″ |
| Apparent magnitude | 2.06 mag |
| Distance | (97.0 ± 1.0) ly |
| Bayer designation | α Andromedae |
| Bright Star Catalogue | HR 15 |
| Hipparcos Catalogue | HIP 677 |
| SAO Catalogue | SAO 73765 |
