Sagitta

Sagitta
Abbreviation	Sge
Genitive	Sagittae
Meaning in English	Arrow
Right ascension	19h 50m
Declination	+18.66°
Visible to latitude	Between 90° and -70°
Best visible	September
Area - Total	Ranked 86th 80 sq. deg.
Number of stars with apparent magnitude < 3	none
Brightest star - Apparent magnitude	Gamma Sge 3.47
Meteor showers	none
Bordering constellations	Vulpecula Hercules Aquila Delphinus

'\Sagitta', the Arrow, is the third-smallest of all constellations (only Equuleus and Crux are smaller). Ptolemy included it in his list of 48 constellations. At that time, however, it was even smaller, spanning only about 4 sq. deg. It's also on the list of 88 constellations now acknowledged by the IAU.
Being located not very far to the north of the equator, this constellation can be seen from everywhere except for the southernmost part of the world.
Sagitta is surrounded by the following constellations (beginning at the north and then continuing clockwise): the little fox Vulpecula, the mythological hero Hercules, the Eagle Aquila and the Dolphin Delphinus.

Table of contents

1 Notable features 2 Notable deep sky objects 3 History 4 Mythology

Notable features

Here are some of Sagitta's brighter stars:

• Alpha (α) Sge: also known as Sham, this yellow bright giant star of spectral class G1 II (with 4.37m) lies at a distance of 610 light-years and together with β Sge (also 4.37m) forms either the feathers of the shaft or the two-pointed arrow once used in the Roman army.
• Gamma Sge (γ) : this cool giant (M0 III, 3.47m) represents with the stars δ Sge and ε Sge the shaft. It lies at a distance of merely 170 light-years.
• Delta Sge (δ): M2 II+A0 V (suspected visual double; probably single image, composite spectrum), 3.82m
• Epsilon (ε) Sge: G8 III, 5.66m, multiple star (4 components; component B is optical)
• Eta (η) Sge: this star of spectral class K2 III with 5.1m belongs to the Hyades moving group.

Notable deep sky objects

• M71: this object is a very loose globular cluster mistaken for quite some time for a dense open cluster. It lies at a distance of about 13.000 light-years and was first discovered by the French astronomer Philippe Loys de Chéseaux in the year 1745 or 1746.

History

In the past Sham designated the whole constellation instead of only α Sge. This constellation is one of those cases where Johann Bayer failed to name the stars in the correct order, in this case even degrading the brightest star to mere γ-status. Another example for such misjudgement is the constellation Orion.

Mythology

Although Sagitta doesn't contain any bright stars, many cultures have seen an arrow in it, among them the Persians, Hebrews, Greeks and Romans. So there are various stories trying to explain the meaning of Sagitta. The two most important ones both take into account the neighbouring constellations Hercules (to the west) and Aquila (to the east).

According to the first one the Titan Prometheus stole the fire from the Gods and brought it to the mortals, thereby irritating Zeus so much that he was chained to a rock in the Caucasus where an eagle (represented by Aquila) ate his liver; as Prometheus was immortal his liver grew back each day, and the eagle would return and eat it again... Heracles (identical to the Roman Hercules) saved him from this never ending punishment during his Eleventh Labour by killing the bird with an arrow shot and then setting him free.

Another story relates how Heracles killed the Stymphalian Birds that terrorized Arcadia. The Stymphalian Birds themselves were identified with the constellations Aquila, Cygnus and Lyra.

Sagitta was further interpreted by some as Cupid's Arrow and as an arrow shot by Sagittarius at Scorpius.

See also Heracles