Blue-white main-sequence star · Sagittarius

Arkab Prior

Also known as: β¹ Sagittarii (β¹ Sgr), HIP 95241

mag 4.0310 light-years

About

Arkab Prior (β¹ Sagittarii) is a blue-white main-sequence star of magnitude 4.0 in Sagittarius, about 310 light-years away.

Arkab Prior is in the constellation Sagittarius.
Best evenings: around late August 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 south of 36° N.

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.

EyesVisible from the suburbs on a clear night, but lost in bright city skies.
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	Arkab Prior
Designation	β¹ Sagittarii (β¹ Sgr)
Hipparcos number	HIP 95241
Type	Blue-white main-sequence star
Spectral type	B9V
Colour	WhiteB−V colour index −0.09
Magnitude	4.0The smaller the number, the brighter.
Distance	310 light-yearsThe light you see left it around 1710.
Proper motion	0.024″ per year across the sky
Constellation	Sagittarius
Right ascension (J2000)	19h 22m 38.3s
Declination (J2000)	−44° 27′ 32″