The name, the history, the myth
Although it is one of the darkest constellations in the whole sky, the constellation of the Cup, also known as Crater, is very old dating back to Ptolemy's time.
Mythologically, the cup is the object with which the raven (represented by the constellation Crow) had to collect the pure water of life on behalf of Apollo, determined to make a sacrifice in honour of Zeus.
Since the bird stopped to eat figs and was late, Apollo sent it to heaven with the cup.
In Roman mythology, besides Apollo, the cup was also attributed to Bacchus, and Hercules, but also to the Greek hero Achilles and many others.
the constellation Crater
First of all the name: with the term crater is not intended an orographic-vulcanic characteristic, but rather a simple cup, a mug.
I was saying that perhaps it is little known, even if it is a little south of the constellations of the Lion and the Virgin, with which it borders: the first of these, the Lion, is really recognizable in the night sky, so it can lead us to the recognition of the Crater. What better opportunity to learn a new constellation and then plan a nighttime observation? In the meantime we see in the image taken from Stellarium the area of sky in which it is located, just north of the constellation of Hydra.
The constellation presents very interesting deep sky objects, but few notable stars, as we will see as we continue the analysis.
The representation of the Crater in antiquity and modernly is quite uniform: here is the version of the Uranometria
This is the Crater according to Hevelius.
and finally according to Stellarium
The stars of the Crater
As anticipated, the Crater has only one big star and one quite close enough.
I start from the biggest star, the star ε Crt, of class K5, and therefore of the same family of the usual Aldebaran, that once again suffers the shame to appear clearly smaller: my Epsilòcrati friends are proud that their star is 1.33 times the antagonist and on precise request they have sent me the photo of their diurnal star from the distance of 10 UA (the average one of Saturn around the Sun).
But they don't see it, since they live on the dark side of their planet which has a synchronous orbit with the star: they are so lazy that they don't want to move towards the illuminated part, since they would suffer there because it's too hot. You have to understand them, but they certainly miss this beautiful spectacle!
Inside the constellation there is a star close enough but not too much, the variable SZ Crt, also known as Gliese 425: it is another relative of Aldebaran, given its spectral class K5 and is placed in the sky at a distance of 44 al.
My friends Senzacriterievocali sent me the photo of our Sun seen from their Szcrtale system: our star appears weak among important stars like Fomalhaut, Raccoon, Sirius and Altair, which they pronounce in a very strange way (Fmlht, Prcn, Sr and Ltr) since in their alphabet they don't have vowels (hence their name). Their star is obviously called Szcrt just as it is obvious that our star is called Sl.
Let's not talk about their social security numbers, but let's go on, because we have other more serious and important things to talk about...
Deep Sky objects
Let us now dedicate ourselves to deep sky objects, which we can admire in all their splendor thanks to the photos of the HST : they are four spiral galaxies.
Let's start with NGC 3511
the galaxy NGC 3511
then we see NGC 3513
the galaxy NGC 3513
It is now the turn of the crossed-out spiral from NGC 3887
the galaxy NGC 3887
and lastly, let's enjoy the spectacle of the beautiful NGC 3981.
the galaxy NGC 3981
Names of stars and visibility
Among the few stars in Crater, three have received names, definitely not used at all.
- Alkes (a Crt): the cup
- Al Sharasif (ß Crt): the handles
- Labrum (δ Tri): the lip
As far as the visibility of the constellation is concerned, at the usual time of 9 p.m., it is low on the horizon, in the South-East, in mid-February, culminating in the South by mid-May, and then low on the horizon, in the South-West, in the last ten days of July.