The following describes objects in our night sky for September and is especially written for beginning observers.
If you do not own a telescope, the club Observatory has a 100mm aperture high quality refractor that is perfect for your use. It is probably a better telescope than most of us ever started Amateur Astronomy with.
You are welcome to use what is your Observatory as a club member. Visual use of the Observatory’s 100mm telescope is the entry level and is not difficult. Contact Mark Town for training. If you have already undergone the training and would like a refresher, arrange to book the Observatory with myself or Mark or another member of the club who is experienced with the facility.
Contact Text Email
Mark Town 0474 859 788 marktown@shoal.net.au
Andrew Wood 0401 907 025 amwood1961@outlook.com
More about Observatory use later.
Eclipse of The Moon
A Total Lunar Eclipse will take place on the morning of September 8. The partial phase will start about 2:30am, with totality lasting from 3:30am to 5am. Saturn will also be at prime position for observing during the eclipse, above the Moon in the west.
While you’re out on this morning, turn to the north-east to see The evening summer constellation of Orion, along with the naked eye star clusters, the Hyades and Pleiades.
Moon Phases
The Deep Sky Objects described later should be visible with the Moon present, although they will be better seen at times when the Moon is not visible. Still, don’t be put off by the Moon if the sky is clear. See what you can and try again on a moonless night.
Sep 8: Full Moon, including the Lunar Eclipse. Afterwards, it wanes through gibbous phases toward…
Sep 14: Last Quarter – rising around midnight. Afterwards, it wanes through crescent phases toward…
Sep 22: New Moon – rising and setting with the Sun. No moon visible all night. Afterwards, it waxes through crescent phases toward…
Sep 30: First Quarter – the Moon rises about midday and sets about midnight.
Planets
Saturn is the only bright planet easily visible to observe this month. It comes to Opposition on Sep 21. This means it lies on the opposite side of the Earth from The Sun, is at its brightest and largest, and is visible all night. A telescope will show the planet’s rings, currently nearly edge-on from our perspective. Titan, the biggest of Saturn’s moons, will be visible in a small telescope. Surface features will require a larger telescope, which may also show several fainter moons.
Deep Sky Objects
Refer to the article: DEEP SKY 101 | Shoalhaven Astronomers on this website for information about the types of Deep Sky Objects.
The picture below shows the area of Scorpius and Sagittarius at 9PM during September. The beautiful constellation Scorpius, one of the few to easily resemble its moniker of Scorpion, is “claws down” toward the western horizon. Above it lies Sagittarius, the Archer; more commonly known today for its teapot asterism. [The picture was created in a free program, Stellarium, which can be downloaded from the internet].
This area of sky abounds in deep sky objects, mainly clusters and nebulae. Those described here are bright examples which can be located with binoculars and are good objects for a small telescope.
Antares, or α-Scorpii, the named star in the picture, is the brightest star in the constellation Scorpius. It shines red and bright to the naked eye, being a red supergiant star 550 light years away. It is a binary star with a faint green companion nearby. Due to the brightness of Antares, however, the fainter star is difficult to see. A much easier binary is object 1 in the picture.
The following are descriptions of the numbered objects [see the end of this article for a primer on terms such as magnitude, M and NGC]
- β-Scorpii, the second brightest star in Scorpius, is a Binary Star. The magnitudes of the components are 2.6 and 4.9, separated by 13.6”. They are 404 light years away.
- M4, also called NGC 6121, is a Globular Cluster. It has a magnitude of 5.9 and is 10,000 light years away.
- M7, also called NGC 6475, is an Open Star Cluster. It has a magnitude of 3.3 and is 800 Light Years away. It is also known as “Ptolemy’s Cluster”. Visible with the naked eye in dark skies, it is visually spectacular even with a small aperture telescope.
- M6, also called NGC 6405, is an Open Star Cluster in the same binocular field as M7. It has a magnitude of 4.2 and is 1,300 Light Years away. It is also known as “The Butterfly Cluster”.
- M22, also called NGC 6656, is a Globular Cluster. It has a magnitude of 5.1 and is 7,800 light years away. This is one of the very bright examples of this type of object.
- M8, also called “The Lagoon Nebula” and NGC 6514, is an Emission Nebula. It has a magnitude of 5.8 and is 4,900 Light Years away.
- M20, also called “The Trifid Nebula” and NGC 3372, is an Emission Nebula in the same binocular field as M8. It has a magnitude of 6.3 and is 2,300 Light Years away.
Having seen these objects through the 100mm refractor in the Observatory, you may want to use a larger aperture telescope for better views. A larger aperture will collect more light and more detail. Inside the Observatory are stored two 200mm telescopes. Learn how to use these telescopes – just ask. They can be used in the area outside the Observatory and can also be borrowed for you to take home.
Notes on Observatory Use
- After dark the university campus is quite empty. I have left very late with no other cars in the car park. This can be daunting and also is a safety issue if you have a fall or other event. It is probably best to have someone with you. On the other hand, it is highly unlikely anyone posing danger will be present, and if you are confident to be able to use the Observatory alone, be careful.
- For Deep Sky Observing, the entry level use is using the hand-controller to move the telescope to objects, then use the dome control to shift the dome so the telescope can see out. The next level is to use the computer to control the telescope and dome. The computer gives out a lot of light, affecting your night vision. For visual observing it is best to close the Observatory entrance to keep the campus lights out, leave the computer off, and use the hand controls. This will mean obtaining a …
- Red-light torch. With all the lights out to preserve your night vision, you will still need to see to move safely around inside the Observatory. Astronomers use red light, which in the visible light spectrum has the lowest energy, to preserve what we call Dark Adaptation. The Observatory does not have a red-light torch; you should bring one with you. Torches with red LEDs can be purchased or get a small torch and tape several layers of red cellophane over the globe.
- Here’s a practical consideration – the Observatory has no toilet, it’s quite a walk to the campus buildings in the dark, and they are probably closed anyway. Make sure you have gone beforehand, and if you are there a long time, you’ll have to use the good old “bush toilet” near the observatory if it becomes necessary. Once again, take care.
- To take refreshment such as water or coffee, or eat snacks, go outside the Observatory.
Some Useful Terms
Aperture is the diameter of the lens or mirror that the telescope uses to collect light.
Magnitude is how bright an object is. Smaller Numbers have Brighter Magnitudes – e.g. Magnitude 1 is brighter than magnitude 2. A very dark sky will allow stars as faint as magnitude 6 to be visible. Very bright objects – bright stars and planets, the Moon and Sun, have negative magnitudes.
Magnification, or Power, is calculated by dividing the focal length of a telescope by the focal length of the eyepiece being used. The 100mm refracting telescope in the Observatory has a focal length of 550mm. The 42mm eyepiece that is in the telescope when you enter the Observatory yields a magnitude of 550/42 = 13. This gives a very wide field of view to locate the object. Exchanging for eyepieces with shorter focal lengths increases the magnification, enabling more detail to be seen. An 8mm eyepiece in our telescope will give nearly 70X magnification.
M stands for objects in the Messier Catalogue of 110 objects. This was one of the earliest lists of deep sky objects compiled in the 1700s. Most of the objects in this catalogue will also have an NGC number.
NGC stands for New General Catalogue. All Deep Sky Objects will have a catalogue number, of which the NGC is the most well-known, with more than 7,000 objects. Many brighter, more well-known objects have names such as Jewel Box, Blue Planetary etc. All of these will also have a number in one of the many astronomical catalogues.
FOR THOSE NEW TO AMATEUR ASTRONOMY
I strongly advise that you purchase or borrow books, or read online sites, devoted to teaching basic Astronomy. Teach yourself about
- Different types of telescopes
- Aperture and Focal Length
- Magnification
- Eyepieces, Barlow lenses and filters
- Navigating the night sky
- Planispheres
- Star Atlases
- Right Ascension and Declination
- Deep Sky Objects – clusters, nebulae and galaxies
Andrew Wood
amwood1961@outlook.com