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Astronomical Observation
When observing at night your first target should be the Moon as it offers a wealth of detail; it is large, bright and
easy to locate. Spend some time with the Moon, high magnifications will show many interesting features. You will
see mountain ranges, craters and evidence of volcanic activity when the Moon was mainly composed of melted
rock. You will need a neutral density filter to observe the Moon, a 13% transparency filter is recommended.
Once confident with the Moon the planets would be the next target. Planets are easy to identify as they are bright
and do not twinkle unlike stars. Please note that when a planet is out of focus and it becomes very dim you may not
be able to see it.
Use the finder-scope to place the planet in the centre of the field of view, then look through the eyepiece and use
the telescope focuser to bring the planet into focus. Planets that are easy to observe include Venus, Mars, Jupiter
and Saturn. You will get the most out of the planets at higher magnifications.
At high magnifications planets will look like marbles and will reveal a high degree of detail to the trained eye.
Jupiter will show banding, the Red Spot and you will also be able to observe the Galilean Moons.
Saturn is probably the most exciting planet to observe through a telescope. While surface detail is subtle its rings
are a unique site and you should be able to observe the Cassini division which appears as a black gap between the
rings.
Mars also known as the Red planet will reveal a good amount of detail when close to Earth. Its orange colour is
prominent and surface markings are visible as are the Polar caps when present.
Venus can be observed early in the morning before dawn or just after sunset. Venus appears quite large in the
telescope but its atmosphere will hide any surface detail.
Deep sky observation greatly depends on the prevailing sky conditions. City lights, low sky transparency and the
presence of the Moon will greatly affect what you can see through the telescope. From a dark site and under
favourable conditions you will be able to see several deep sky objects including star-clusters, galaxies, nebulae and
comets. Such objects with the exception of stars will appear as feint clouds of matter in monochrome, human eyes
are not able to pick up colour. Cameras on the other hand can reveal colour and considerable amounts of detail.
Good deep sky objects to look for at the very beginning include the Orion Nebula, the Trifid nebula, the Ring
nebula, the Andromeda Galaxy and a number of star-clusters among various other objects.
Observation Skills
In general it is easier to locate a target with a low power eyepiece i.e. 25mm. Once the target has been located
centre it in the field of view before replacing the 25mm eyepiece with a high power one, i.e. 5mm (x240).
There are many factors that will affect the quality of the image through the eyepiece; such factors include sky
quality in terms of the level or light pollution, sky transparency and the presence of the Moon if you are observing
deep sky objects like galaxies and nebulae. If you use an equatorial mount make certain that the telescope has been
balanced and that all screws are reasonably tight.
You will always be limited by the type, size and the optics of your telescope in what you can see. However there
are other important factors to consider that can substantially improve the experience. Let the optics to cool down
for best results, this varies depending on the size and type of the telescope but typically a 152mm refractor like the
ARC-152 will need around 15 minutes to cool down.
Please keep in mind that targets near the horizon will not look as sharp, targets near the zenith will look
substantially sharper. Avoid setting your telescope on concrete; wood and grass are better as they do not release
heat. Your line of sight should ideally not pass just over a warm house; the rising heat will substantially affect the
quality of the image.
The long focal length of the ARC-152 scope makes it ideal for planetary and Lunar viewing. When conditions are
not favourable the maximum useful magnification for most scopes will be around 25-35 times per inch of aperture.
Otherwise expect higher practical magnifications per inch of aperture under favourable conditions with good
quality eyepieces.
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