Canis Minor

Authors: Susanne M Hoffmann, Doris Vickers, Youla Azkarrula

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CMi star chart (IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg).

One of the 88 IAU constellations. In antiquity, this area was named "pro kyon", "the one [star] before the dog". The name ‘Little Dog’ for the constellation is first documented by Ptolemy; however, Eratosthenes already mentions a group of three stars, which is the Hound of Orion. In the Almagest, two stars are listed for this constellation. This can therefore never have been descriptive, but was merely a name.

Orion-Group of constellations on the Kugel Globe, drawing and animated GIF by SMH 2025.

Etymology and History

Origin of Constellation

Aratos, Eratosthenes, Hipparchus and other Greek astronomers call the constellation Procyon, the name we ascribe to the brightest star today. The star Procyon therefore has one of the few original Greek names: ‘pro’ means ‘before’ and ‘kyos’ is the dog. The Procyon is therefore the ‘pre-dog’ or ‘the star that rises before the dog’, as Eratosthenes unimaginatively explains. Ptolemy calls the single star Sirius ‘the dog’ and therefore only a single bright star is the ‘pre-dog’. Just as the Egyptian word ‘Sothis’ for a group of three stars was later reduced to a single star (Sirius), the Greek word ‘Procyon’ suffered the same fate.

The bright star Procyon was possibly used in Mesopotamia as an indicator for the rising of Cancer. The stars in Cancer are so faint that you can barely see them at dusk - but the bright Procyon rises at the same time, which is suitable for telling the time.

Greco-Roman

Aratus

But yet another constellation sweeps across the horizon: they call it the Hydra. Like a living thing [445] it winds at great length, its head comes below the middle of the Crab, its coil under the Lion’s body, and its tail hangs over the Centaur himself. On its middle coil lies the Bowl, and on the last one the figure of a Raven that looks like one pecking the coil. [450] Yes, and there too Procyon shines brightly beneath the Twins. (Kidd 1997)

Hipparchus

Rising (Lib III Cap I §13)

The Rising of ...

	east		south
	lam1	lam2	lam1	lam2
	Cnc 3 1/2	Cnc 9	Psc 15	Psc 19 1/2
star	the front one which is double (bet, gam)	the rear and bright one
duration	1/3 hours = 20 min = 5 degree

Setting (Lib III Cap II §13)

	west		south
	lam1	lam2	lam1	lam2
	Gem 15	Gem 18	Lib 1	Lib 4
star	the front one which is double (bet, gam)	the rear and bright one
duration	1/5 hours = 12 min = 3°

Stars Mentioned

	Greek	German	English	ident.	src		lam_culm
					Lib II Cap V §10	rising, east, first
					Lib II Cap V §10	rising, east, last
					Lib II Cap VI §2	setting CrB, south, last	Psc 13.5
					Lib II Cap VI §13	setting Aql, south, first	Ari 2
					Lib III Cap I §9	rising Ori, south, last	Psc 13

Hyginus, Astronomica

Procyon seems to rise before the greater Dog; for this reason it is called the Fore-dog. By some it is thought to be Orion's dog, and it is put in all the same tales in which the greater Dog is numbered. (Mary Ward 1960)

Ancient Globes

The Lesser Dog is only depicted on the Kugel Globe; it is absent on the Farnese Globe and the Mainz Globe.

Almagest Προκύων

id	Greek (Heiberg 1898)	English (Toomer 1984)	ident.
	Πρόκυνος ἀστερισμός.
1	ὁ ἐν τῷ αὐχένι	The star in the neck
2	ὁ κατὰ τῶν ὀπισθίωυ λαμπρὸς καλούμενος Προκύωυ.	The bright star just over the hindquarters, called Procyon
all	ἀστέρες β, ὧν α μεγέθους α, δ’ ἄ.	{2 Stars, 1 of the lirst magnitude, 1 of the fourth}

Convex Hull for the stars inside Prokyon (CC BY Youla Azkarrula).

Stars within the Constellation Area

id	Label	IAU design.	description	Vmag
1	Procyon	HIP 37279	Constellation lines	0.37
2	Gomeisa	HIP 36188	Constellation lines	2.89

Transfer and Transformation of the Constellation

• 
  Canis Minor on the Kugel Globe (1st c. BCE), drawing by SMH 2021
• 
  Canis Minor in Bayer's Uranometria (1603)
• 
  Canis MInor in Hevelius (1690)
• 
  Canis Minor with Gemini in Flamsteed (1728)
• 
  Canis Minor in Bode (1782/1805)
• 
  Canis Minor in Jamieson (1822)
• 
  Canis Minor in Hall (1825)

Mythology

It was the Roman mythographer Hyginus who first handed down a legend about this constellation: if this dog was the dog of Ikarios - which Eratosthenes describes as one of the legends of the Great Dog - then this dog committed suicide when his master was murdered: the wine produced in ancient Greece was very strong and would probably be difficult for us to drink today. It wasn't easy to drink back then either. Ikarios is considered to be the one who introduced winemaking to Athens and it is said that he was murdered by some customers while intoxicated. His dog reported the crime by barking, but when he realised that his master could not be saved, he himself no longer wanted to live.

References

• References (general)
• References (Babylonian)
• References (ancient Greco-Roman)
• References (medieval)