Blue-white subgiant · Cygnus

Azelfafage

Also known as: π¹ Cygni (π¹ Cyg), HIP 107136

mag 4.71,700 light-years

About

Azelfafage (π¹ Cygni) is a blue-white subgiant of magnitude 4.7 in Cygnus, about 1,700 light-years away.

Azelfafage is in the constellation Cygnus.
Best evenings: around early October it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
Where on Earth: it is seen well, at least 10° up, from north of 29° S.

When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.

EyesNeeds a dark sky away from city lights.
Binoculars (10×50)A sharp point; binoculars bring out its colour and the fainter stars around it.
Telescope (6–8 inch)Still a point of light at any magnification — stars are too far away to show a disc. Low in the sky, bright stars twinkle and flash colours.

Stars look the same in any instrument: brighter and sharper, but never bigger.

Proper name	Azelfafage
Designation	π¹ Cygni (π¹ Cyg)
Hipparcos number	HIP 107136
Type	Blue-white subgiant
Spectral type	B3IV
Colour	Blue-whiteB−V colour index −0.12
Magnitude	4.7The smaller the number, the brighter.
Distance	1,700 light-yearsThe light you see left it around AD 300. Distances this large are uncertain by 10% or more.
Proper motion	0.006″ per year across the sky
Constellation	Cygnus
Right ascension (J2000)	21h 42m 05.7s
Declination (J2000)	+51° 11′ 23″