Delphinus is a faint, small constellation below Cygnus. Its brightest star Rotanev (Beta Delphini) is magnitude 3.6 and the second brightest, Sualocin, is magnitude 3.8. The other main stars are all below magnitude 4.0. However, and somewhat surprisingly, it is fairly easily made out, because it is small and forms a shape like a tadpole, rather than a dolphin. The quadrilateral which forms the body of the tadpole is called Job’s Coffin. It is an ancient constellation, which either represents the dolphin which fetched the nymph Amphitrite for Poseidon or the one which rescued the poet and musician Arion when he was robbed at sea. It is possibly more relevant that dolphins were revered by the Minoan civilisation on Crete.

The names of the two brightest stars, which first appeared in the early nineteenth century Palermo catalogue, were a puzzle for many years until the amateur astronomer Rev. Thomas Webb surmised that they spelt Nicolaus Venator backwards. This was the Latinised name of Niccolò Cacciatore, who was the assistant to Giuseppe Piazzi, the director of the Palermo Observatory and he possibly so named them as he felt he deserved greater credit for compiling the catalogue. Delphinus acquired a new star recently when Rho Aquilae (mag. 4.9) moved across the boundary between Aquila and Delphinus as a result of proper motion. It lies roughly half-way between Delphinus and Sagitta. Delphinus is famous for another kind of new star (novae), with naked eye novae in 1967 and 2013.

There is only one notable deep-sky object in Delphinus, the globular cluster NGC 6934 [1], which is also Caldwell 47. This is a fairly compact globular cluster which is, however, both small and rather dim (mag. 8.8). There is one notable double star, namely Gamma Delphini, a binary star of magnitude 4.4 and 5.0 with a fairly narrow separation of 8.8 arcseconds. It is seen as yellow and blue, but is sometimes observed as two yellow stars which better matches their spectral classes of K and F.

Equuleus (meaning the little horse or foal) is equally small and even fainter. The brightest star Kitalpha (from the Arabic for “piece of the horse”) or Alpha Equulei is magnitude 3.9, but the other three stars in the quadrilateral are fifth magnitude. It appears in Ptolemy’s catalogue of constellations and survived the reform of 1922, but there are no convincing myths about it. Perhaps it was regarded as the foal of the neighbouring constellation of Pegasus. It is rather bereft of deep-sky objects. There are, however, two worthwhile double stars. Gamma Equulei is an extremely wide optical double with 6 Equulei. The stars are magnitudes 4.7 and 6.1 with a separation of 335 arcseconds; they are seen as both white or bluish white and white. Epsilon Equulei [2], which is almost in Delphinus, is another optical double of magnitudes 5.3 and 7.1, which are 10.6 arcseconds apart. The main star is usually seen as yellow, but opinions differ about the secondary, with blue and red being reported. They are in fact both spectral class F.