The September Sky

Paul Curtin

Note: On 07 September a partial lunar eclipse will be visible in Europe, Africa, and Asia. Observers in Africa and South America will be able to observe an annular eclipse on 22 September.

The summer triangle still dominates the northern sky this month, but don’t overlook the small constellations in this region as they contain some very nice objects. Delphinus is a fine area to scan with binoculars. See if you can split the double star gamma at the tip of the dolphin’s nose. NGC 7006, a small globular cluster, and NGC 6891, a compact planetary nebula, are impressive in mid-sized telescopes.

The faint box-shaped constellation Equuleus introduces a recurrent theme in the northern autumn sky: dark sky and difficult objects. A number of its stars are multiple but the most interesting part of this sector is the globular cluster M15, in western Pegasus.

Western Aquarius has a nice variety of deep-sky objects. NGC 7009, the Saturn Nebula, is a bright planetary well worth the search. M73 is a very nice open cluster in a wide-field telescope. The tiny globular cluster M72 is a very nice sight.

To the south is the large boat-shaped constellation Capricornus. The stars alpha, sigma, beta and rho are multiples with lovely color contrasts. The globular cluster M30, south-east of zeta Capricorni, and M75 (actually in eastern Sagittarius) are the only deep sky objects visible without very large telescopes. Solar system enthusiasts should take the opportunity to locate Neptune. It can be found in the area north of theta Capricorni.

The edge of spring in the southern sky is dark. Microscopium has some double stars but little else of note. Indus contains some galaxies but even these peter out as we move southward to the very dark area of Octans and the south celestial pole.

The Planets in September

Mercury enters the evening sky towards the end of the month.

Venus is very low in the morning sky, becoming lost in the glare at the end of the month.

Mars cannot be seen this month.

Jupiter is in Libra. It can still be observed in the early evening.

Saturn, in Leo, is a morning object.

Neptune is in Capricornus. The next few months are fine opportunities for locating this faint planet.


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.