The Constellations
Light skies bring frustration to astronomers but at least the nights are now drawing in. Observing becomes a late night / early morning event, not for the tired or weary amongst us. The rewards however yield the delights of our galaxies centre with the star clouds and nebulae of Sagittarius and Scorpius. The “Summer Triangle”, consisting of; Deneb, Vega and Altair dominates the sky.
Scorpius
Scorpius “The Scorpion” is one of those constellations that at least semi resemble the object that it is meant to. The constellation is dominated by Antares a red supergiant of spectral type M1 which is the 15th brightest star in the sky, it shines at magnitude 0.96.
Objects of interest include the globular clusters M4, M62 and M80 as well as the open clusters M6, M7 and NGC 6231
Sagittarius
Sagittarius “The Archer” is located in the direction of the centre of The Milky Way, as such it is littered with numerous deep sky objects, unfortunately it never rises very high to UK observers and a clear dark southern horizon is essential for viewing.
Objects of note include, on the Nebula front: M8 (The Lagoon Nebula), M17 (The Omega Nebula), M20 (The Triffid Nebula). Globular clusters include M22, M28, M54, M55, M69, M70 and M75. Open clusters include M18, M21, M23, M25 and the star cloud of M24.
Serpens Cauda and Serpens Caput
This constellation represents the serpent being carried by Ophiuchus and is split in two, Serpens Cauda “The Tail” and Serpens Caput “The Head”.
The two main objects of note are located one in each of the tail and the head. The globular cluster M5 can be found in Serpens Caput while M16 “The Eagle Nebula” can be found in Serpens Cauda.
Scutum
Scutum “The Shield” is a pretty dull constellation and is noted for it’s two Messier objects M26 and M11 (The Wild Duck Cluster).
Sagitta
Sagitta “The Arrow” is a feint obscure constellation that only has one object of note M71 that is a globular cluster although it can be confused as an open cluster.
Vulpecula
Vulpecula “The Fox” is most famous for its spectacular planetary nebula, M27 “The Dumbell”, this is a spectacular sight even through a 6” scope and through the societies 12” scope it is truly remarkable looking exactly like the pictures seen in most books.
There is also NGC 6940 an open cluster located very close to the constellation boundary with Cygnus.
Lyra
Lyra “The Lyre” contains Vega, magnitude 0.0, the brightest star in the northern celestial sphere. Of special note for double star observers is the famous epsilon Lyrae “double double” multiple star system. Epsilon 1’s components are magnitudes 5.0 and 5.1 and Epsilon 2’s components are 5.2 and 5.5.
Lyra contains the globular cluster M56 which is located roughly half way between Sulaphat (Gamma Lyrae) and Albireo (Beta Cygni).
The most famous deep sky object in Lyra is M57 “The Ring Nebula” which resembles a smoke ring. I must admit after looking at all the fine pictures of this in virtually every astronomy book it is rather disappointing when observed visually to see that it does not display the colours depicted in the photographs and is a rather bland greyish green colour.
Cygnus
Cygnus “The Swan” is a wonderful sight through binoculars as the Milk Way runs straight through it. Cygnus contains the open clusters M29 and M39 that are both pleasing targets through binoculars, M39 being the brighter of the two (mag 4.6). M29 is easier to locate as it is located next to Sadr (Gamma Cygni).
Cygnus also contains two rather challenging nebulae, both well known, NGC 7000 “The North American Nebula” and NGC 6960 “The Veil Nebula”. Be warned both are elusive, NGC 7000 because it is so widespread and diffuse (apparently its best observed in binoculars although I’ve never seen it) and NGC 6960 is best observed through an OIII filter in very dark skies.
Hercules
Hercules is the fifth largest constellation in the night sky covering 1225 degrees and is best located by finding its familiar keystone pattern. Hercules appears inverted from a UK observers perspective.
Rasalgethi (Alpha Herculis) is a supergiant of spectral type M5, although designated “Alpha Herculis” it is in fact the third brightest star in the constellation. Rasalgethi is located at a distance of 218 light years and is a vast star that may be even larger than Betelgeuse (Alpha Orinis) with a supposed diameter of over 250 million miles.
Ophiuchus
The 13th constellation of the Zodiac, Ophiuchus lies on the Zodiac, however, it is not recognised by Astrologers. It represents a serpent, Serpens, coiled round a man's, Aesculapius', body. Aesculapius is believed to have preceded Hippocrates as an early healer who was supposed to be able to raise the dead. To this day, the serpent is the medical symbol of healing.
The best known star in Ophiuchus is Barnard's Star, magnitude 9.5, the second closest to our Sun, and one of the first thought to have a planetary system.
The southern part of the constellation lies in the Milky Way, looking towards the centre of our galaxy, and is a good source of star clusters and other objects. Ophiuchus is the site of the last supernova seen in our own galaxy in 1604. There is also a recurring nova, RS Ophiuchi, which flares up every 20 years or so. It was last seen in 1985, 1967, 1958, 1933 and 1898. Normally magnitude 12, it brightens to naked eye visibility. Principal stars are: Rasalhague -Alpha Ophiuchi, magnitude 2.6; Cebalrai - Beta Ophiuchi, magnitude 2.8; Yed Prior - Delta Ophiuchi, magnitude 2.7; Gamma Ophiuchi, magnitude 3.8.
Deep Sky objects in Ophiuchus are M9, M10, M12, M14, M19, M62, M107, NGC 6369.
