Star Stars · In Scorpius
Girtab
Girtab, κ Scorpii, is a blue-white giant in Scorpius: the 85th brightest star in the night sky.
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- Constellation
- Scorpius
- Designation
- κ Scorpii
- Apparent magnitude
- 2.39 · 85th brightest star in the night sky
- Spectral class
- B1.5III
- Distance
- 483 light-years
- Highest at midnight
- mid June
- Position (J2000)
- RA 17h 42m · Dec −39° 02′
A blue-white giant, around 27,000 K, like Rigel and Spica. About 44× brighter than the faintest star the eye can see. Gives off about 2,000 times the Sun's visible light. The light you are seeing left around 1543.
When to see it
On the night of Mon 14 Jun 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never rises | ||
| New York EDT | 22:04 | 01:07 · 10° | 04:09 |
| Singapore GMT+8 | 19:23 | 01:17 · 50° | 07:12 |
| Sydney GMT+10 | 15:58 | 00:08 · 85° | 08:19 |
Common questions
- Can I see it from 50° north?
- Only just. At its highest it is 1° above the southern horizon, so it needs a clear, flat view that way and clean air.
- Can I see it from 35° south?
- Yes, and well placed: at its highest it passes almost overhead, 86° up, above most of the air’s haze.
- When is the best time of year to see it?
- Around mid June, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid September it is highest in the early evening, and in mid March not until the hours before dawn.
- How far away is it, and how bright?
- It is 483 light-years away, and shines at magnitude 2.39 in our sky. From that far, the Sun would be a star of magnitude 10.7: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.39 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Shaula: Girtab is 2.6° south-east of it, two fingers at arm’s length.
Look for
From 50° north it barely clears the horizon, at 1°; from 35° north it climbs to 16°; from the equator it climbs to 51°; from 35° south it climbs to 86°.
Science
Girtab’s surface is about 27,000 K, some 21,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 110 nm, in the ultraviolet, past the violet end of what the eye can see, where the Sun’s is strongest at 500 nm. Moved to 33 light-years, the distance astronomers compare stars at, it would shine at magnitude −3.5, brighter than Sirius, the brightest star in our sky.
Did you know
Against Shaula, the brighter star the hop starts from: Shaula looks 2.0 times as bright as Girtab in our sky; Shaula is 571 light-years away and Girtab 483 light-years, so side by side Shaula would give off 2.8 times as much light as Girtab.
Science
Girtab is the 124th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Shaula, about 91 light-years from it; on our sky the two are 2.6° apart.
Look for
The Sun passes 16° north of Girtab around mid December, when it is highest at noon, in daylight: the weeks either side are its worst time of year. From 50° north it is above the horizon for about 2 hours a day, from 35° north about 7 and from 35° south about 17. It is 5° from the plane of the Milky Way, inside the band a dark sky shows.