Eye on the Sky October 2006

Paul Curtin

In the north we see the eastern edge of the Milky Way swinging west and leaving us the star-poor, yet more subtle skies of Autumn. Cepheus, a house-shaped circumpolar constellation, offers the last of our galaxy’s bounty. Look for mu Cephei, the garnet star, a reddish-orange star at the base of the “house.” Due south of mu is IC 1396, a nice collection of stars embedded in an extended emission nebula. Xi, in the very center of the house, is a binary that can be split with small telescopes. NGC 6939, an open cluster, and NGC 6946, a galaxy, can be found south of eta and theta Cephei. Eta and theta form a tail running west of alpha. Even if you cannot locate these items you may enjoy some of the interesting chains of stars in this region. Southern Cepheus is a fine area to sweep with binoculars.

Beneath Cepheus is Lacerta, hanging half in, half out of the Milky Way. It’s northern sector presents a nice view in binoculars but in general large telescopes are needed to appreciate its deep-sky objects.

In the dark northeast of Lacerta look for the large square of Pegasus. Though we find a sprinkling of galaxies in Lacerta, it is in Pegasus that they really bloom. The one deep-sky exception to this is M15, a globular cluster west of epsilon near the border with Equuleus. A good beginners project is to see how many stars can be counted inside the great square with the naked eye.

South of Pegasus look for the western section of Pisces characterized by the rough circle of the western fish. This part of the constellation contains some very faint galaxies but few easy deep-sky objects. We will return to the eastern sector in November.

Aquarius, like Pisces, can be divided into two sectors. Unlike Pisces, however, the western region of Aquarius has a number of interesting objects. Near epsilon one finds the globular cluster M72, the collection of stars known as M73, and the the bright planetary nebula NGC 7009, the Saturn Nebula. 7009 can be found roughly 3/4 of the way from epsilon to nu. North of this area intrepid galaxy seekers can find two compact galaxy fields near the border with Equuleus. The globular cluster M2 is due north of beta. East of M2 is alpha, east of this is the “water Jar”, an asterism composed of gamma, pi, zeta and eta. Zeta is a fine double , both stars yellow, that can be split with small telescopes. Due south (almost 20 degrees south that is!) is NGC 7293, the Helix Nebula. In a dark sky this smokey ring can be very impressive.

The bright star dominating the darkness south of Aquarius is Fomalhaut in Piscis Austrinus. Beta, due west of Fomalhaut, is a nice double with blue-white contrast. The rest of the constellation hosts faint galaxies requiring larger telescopes.

Continuing south we find Grus, which bears a slight resemblance to Cygnus but lacks the star clouds and nebulae of the northern bird. In dark skies there are a number of galaxies to find in Grus. Tucana would be unremarkable if it did not contain two of the greatest deep sky objects: 47 Tucanae, a very dense, bright globular cluster, and the Small Magellanic Cloud. Both are truly outstanding objects that merit close study.

The PLANETS in October

Mercury can be glimpsed in the early evening sky for the first half of the month.

Venus cannot be seen this month.

Mars also cannot be seen this month.

Jupiter closely follows the sun and is difficult to find at dusk.

Saturn is in the early morning sky this month.

Uranus is in Aquarius and can be observed throughout the night all month.

Neptune is in central Capricornus and is well placed for observing in October.


Bibliography

Burnham, Robert Jr., Burnham's Celestial Handbook, New York: Dover,
1978.

Jones, K.G. (ed.) Webb Society Deep-Sky Observers Handbook, Volume. 3.
Hillside, NJ: Enslow Publishers, 1980.

Kepple, G. R., Sanner, G. W., The Night Sky Observers Guide, Richmond,
Virginia: Willman-Bell, 1999.

Tirion, W., Rappaport, B., Remaklus, W., Uranometria Deep Sky Atlas,
Richmond, Virginia: Willman-Bell, 2000.

Webb, T. W., Celestial Objects for Common Telescopes, New York: Dover, 1962.