The following describes objects in our night sky for October 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.

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.

October starts with the Moon having just passed First Quarter, becoming more gibbous each day until…

Oct 7: Full Moon – rising around sunset. Afterwards, it wanes through gibbous phases toward…

Oct 14: Last Quarter – rising around midnight. Afterwards, it wanes through crescent phases toward…

Oct 21: New Moon – rising and setting with the Sun. No moon visible all night. Afterwards, it waxes through crescent phases toward…

Oct 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 has just passed Opposition and is already well up in the east as dark sets in. A small aperture telescope will show the planet’s rings, currently nearly edge-on from our perspective. Titan, the biggest of Saturn’s moons, will also be visible in a small telescope. Surface features will require a larger telescope, which may also show several fainter moons.

A twilight conjunction of Mercury and Mars will occur in the late afternoon twilight in the west. They will be close from 19^th – 23^rd, and on the 23^rd the crescent Moon will also be in the picture. This is mainly a naked-eye event, although imaging will be worth a try. You will need a fairly clear western horizon.

To view Jupiter, which rises about 1am, you will need to be out a couple of hours before dawn.

Another reason to be out before dawn is the Orionid Meteor Shower, which peaks on the 21^st at New Moon and may produce 20 or more meteors per hour.

Deep Sky Objects

Refer to the article: DEEP SKY 101 | Shoalhaven Astronomers on this website for information about the types of Deep Sky Objects.

Compared with the September 2025 post, the picture below shows a wider area around Scorpius and Sagittarius at 10PM Eastern Daylight-Saving time during October. This area of sky abounds in deep sky objects, mainly clusters and nebulae. If you have access to a atlas, either a book or digital, and a telescope, you can spend many nights over many years exploring this region. Those objects described here are some more bright examples which can be located with binoculars and are good objects for a small telescope.

 

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]

1. NGC 6231, also known as the False Comet Nebula and the Northern Jewel Box, is, at magnitude 2.6, a very bright and large Open Cluster adjacent to the star zeta-Scorpii, which is at the kink in the scorpion’s tail. In a good sky its nature can be seen with the naked-eye and easily in binoculars. A small telescope at low magnification gives a great view. The Cluster is 5,900 light years away.
2. M62, also called NGC 6266, is a Globular Cluster located at the tip of an equilateral triangle with the two stars in Scorpius’s tail directly above Antares. It has a magnitude of 6.6 and is 22,500 light years away.
3. M28, also called NGC 6626, is a Globular Cluster located close to lambda-Sagittarii. It has a magnitude of 6.9 and is 19,000 light years away. [On the other side of lambda-Sagittarii, and closer to the star than M28, is another Globular Cluster, NGC 6638. At mag 9.2 it is much fainter.]
4. M11, also o called NGC 6705, and the wonderful name of Wild Duck Cluster, is a bright Open Cluster rich in stars, located in Scutum, The Shield. The main stars in Scutum are only of magnitude 4, so it a faint constellation. M11 is located nearby to beta-Scuti, the second brightest stars of the group. The cluster is magnitude 5.8 and is 5,500 light years away.
5. Beta-Sagittarii. Above the main “Teapot” asterism of Sagittarius is a faint but distinct curved group of stars in the constellation Corona Australis, The Southern Crown. Above them, in the outskirts of Sagittarius, lies its second brightest star, beta-Sagittarii. It is actually a naked-eye double, β-1 and β-2. β-1 is itself double, with components of mag 4.0 and 7.2 separated by 29”. Even a small telescope will show the fainter companion.
6. NGC 6441. I have added this as it is fainter and smaller than the objects above, but so near to the star G-Scorpii – just off the tail-end of Scorpius – it is very easy to find. Aiming a telescope at the star will show a fuzzy spherical patch nearby, obviously a Globular Cluster. NGC 6441 is magnitude 7.4 and lies 34,000 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