# Delta Cephei (δ Cep)

Delta Cephei (δ Cep) is a double star in the constellation Cepheus, magnitude 4.2.

The prototype Cepheid variable (magnitude 3.5–4.4 every 5.4 days), with a wide bluish companion. Its components (magnitudes 4.2 and 6.1; spectral types F5 Iab (yellow-white) and B7 (blue-white)) lie 41″ apart at PA 192° (measured 2025).

## When and where to see it

It is best placed in the evening sky around October, when it crosses the meridian at about 10 pm local time (around midnight in August). It can be seen from everywhere north of 32°S and never sets north of 32°N.

At its highest it stands 82° up from 50°N, 67° up from 35°N, 32° up from the equator, below the horizon from 35°S.

## Facts

- Type: Double star
- Constellation: Cepheus
- Designations: δ Cep, 27 Cep, 27 Cephei, STFA 58, HIP 110991
- Magnitude: 4.2
- Position: RA 22h 29.2m, Dec +58° 25′ (J2000)

Open AstroPilot to see when Delta Cephei (δ Cep) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/delta-cephei