dimanche 31 août 2008

Corvus 5

Corvus is a small, faint, and very old constellation.
Corvus, the Crow, was called the Raven by ancient Greeks. The story goes that Apollo sent the raven, or crow, to collect water in the nearby cup ("Crater" = goblet). But the bird wasted its time eating figs. Then, as an excuse for losing time, it gathered up the Water Snake (Hydra) in its claws and flew back, telling Apollo that this creature was the reason for its delay.
Apollo would have none of it, and threw all three: the crow, the goblet, and the water snake, into the heavens. For penance, the crow was made to suffer eternal thirst (and this makes the bird caw raucously instead of sing like normal birds).
Corvus has only a few Bayer stars. As for possible objects of interest, there are two double stars, a variable, and a curious deep sky object.

Double stars in Corvus:
Zeta Corvi is an optical binary: 5.0, 13.0; PA 66º, separation 11".
Delta Corvi is a fixed binary: 3.0, 9.2; PA 214º, separation 24".
The wide separation makes it a fine object for small telescopes; its colour contrast adds to the attraction: a white primary and purplish (or lilac) companion.
Struve 1669 is a pleasant double of equal stars: 6.0, 6.0; PA 309º, separation 5.4".
The binary is five degrees north-northeast of delta Corvi.
Incidentally, 1.5 degrees north of this binary is M104 (Sombrero Galaxy) in Virgo.

Variable stars in Corvus:
R Corvi is a long-period variable with a range from 6.7 to 14.4 every 317.03 days. In 2000 the maximum should occur in the latter half of April.

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