Today we'll examine a constellation not many people will have heard about. It is called 'Sagitta' and is located beyond the north border of Aquila, the eagle, east of Delphinus, the Dolphin, and north of the constellation of Hercules. The ancient Hellenes called the constellation 'Oistos', and even though it is the third-smallest area of all constellations, it was included among the 48 constellations listed by  Ptolemy. It remains one of the 88 modern constellations defined by the International Astronomical Union. Located to the north of the equator, Sagitta can be seen from every location on Earth except within the Antarctic circle.

Sagitta looks like an arrow, and obviously, it is identified with pretty much every archer in ancient Hellenic mythology. For such a tiny constellation is has a lot written about it, mostly by Hyginus in his 'Astronomica'. Above all, he attributes the flying arrow to Hēraklēs, shot to kill the eagle that ate the liver of Prometheus night after night.

"This arrow, they say, is one of the weapons of Hercules, with which he is said to have killed the eagle which ate the liver of Prometheus. The following reason for the release of Prometheus has been handed down. When Jupiter, moved by the beauty of Thetis, sought her in marriage, he couldn’t win the consent of the timid maiden, but none the less kept planning to bring it about. At that time the Parcae were said to have prophesied what the natural order of events should be. They said that the son of Thetis’ husband, whoever he might be, would be more famous than his father. Prometheus heard this as he kept watch, not from inclination but from necessity, and reported it to Jove. He, fearing that what he had done to his father Saturn in a similar situation, would happened to him, namely, that he would be robbed of his power, gave up by necessity his desire to wed Thetis, and out of gratitude to Prometheus thanked him and freed him from his chains. But he didn’t go so far as to free him from all binding, since he had sworn to that, but for commemoration bade him bind his finger with the two things, namely, with stone and with iron. Following this practice men have rings fashioned of stone and iron, that they may seem to be appeasing Prometheus. Some also have said that he wore a wreath, as if to claim that he as victor had sinned without punishment. And so men began the practice of wearing wreaths at times of great rejoicing and victory. You may observe this in sports and banquets.

But to come back to the beginning of the inquiry and the death of the eagle. Hercules, when sent by Eurystheus for the apples of the Hesperides, out of ignorance of the way came to Prometheus, who was bound on Mount Caucasus, as we have shown above. When victor, he returned to Prometheus to tell him that that dragon we have mentioned was slain, and to thank him for his kindness since he had pointed out the way. Straightway he gave what honour he could to the one that deserved it, for [he killed the eagle?] and since it was slain, men began, when victims were sacrificed, to offer livers on the altars of the gods to satisfy them in place of the liver of Prometheus."

Another explanation Hyginus gives--along with Hesiod, Apollodorus, and Diodorus, amongst others--is that the arrow belongs to Apollon. It was the arrow with which He avenged the death ofHhis son Asklepios, who had been killed by a lightning bolt design by the Kyclopses. Obviously, Apollon could not attack Zeus, so he attacked the Kyklopses instead, and murdered them. To quote Hyginus

"Eratosthenes says about the Arrow, that with this Apollo killed the Cyclopes who forged the thunderbolt by which Aesculapius died. Apollo had buried this arrow in the Hyperborean mountain, but when Jupiter pardoned his son, it was borne by the wind and brought to Apollo along with the grain which at that time was growing. Many point out that for this reason it is among the constellations."

Sagitta is visible at latitudes between +90° and −70°, and best visible at 21:00 (9 p.m.) during the month of August.