Limitations of your instrument;
It is important to know the capabilities and limitations of your instrument, and to be able to maximize the conditions required for a good view. Check the limiting magnitude of your telescope. (Each successive magnitude of a star is 2.5X fainter, with the star “Vega “ as the standard 0.0; a magnitude 1.0 star is then 2.5X fainter than “Vega”.) If you have an 80 mm refractor with the faintest stellar magnitude of 12.2, it is pointless to try to observe a fainter object under any condition.
Site selection;
By far the most important factor for successful viewing is site selection. Faint objects are difficult or impossible to see if you are in an area with smog and a lot of lights.
“DO” Travel to the best site as possible. This place should be away from city lights, and should be upwind from any source of pollution. Always choose as high an elevation as possible; this will get you above some of the lights and pollution, and will ensure you aren’t cursed by ground fog.
“DO” Observe on flat ground , away from buildings, walls or natural obstructions. Stay away from any sources of heat.
“DO” Observe on the ground. If you try to observe on any structure, or even a sidewalk, any movement or vibrations will transfer into the telescope. Pavement and concrete store heat which will affect observing.
“DO” Make sure that you have a dark, unobstructed view of the horizon, especially to the south if you are in the Northern Hemisphere, and visa versa.
“DON’T” Try to use your telescope in the middle of a city, unless you only want to look at very bright objects.
“DON’T” Try to observe any object when the light path is near any protrusion on the ground. Even extremely light winds can cause major air turbulence as they flow over the top of a building or wall.
“DON’T” Observe from your house, deck, apartment, and never observe through a window.
Before you head out to your chosen site, there are a few things to check prior to starting your evening of observing.
“DO” Check the weather forecast. The best conditions will have still air, and a clear view of the sky. It is not necessary that the sky be cloud-free. Often broken cloud conditionshave excellent seeing.
“DO” Observe the night’s objects as they cross the meridian. The Meridian is an imaginary line that runs from the Zenith, due North – South. This is the point at which objects are highest in the sky. Observing at this time reduces all of the bad effects of the atmosphere.
“DO” Give your optics time to adjust to ambient air temperature. Your mirror or lens is changing shape as it cools, resulting in a poor image. Allow longer cooling times for larger optics. I f you are using an equatorial mount, use this cooling down time to perform your Polar alignment.
“DON’T” plan to observe in changing weather systems; ther is always turbulence.
“DON’T” observe near the horizon. You will be looking through a lot of atmosphere complete with turbulence, dust particles, and increased light pollution.
DON’T” view immediately after sunset. After the Sun goes down, the Earth is still cooling, causing air turbulence. As the night goes on, seeing will improve, air pollution and ground lights will often diminish. Often the best viewing times are the early morning hours.
You now have your telescope set up in a good viewing area, at a good time. To get the most out of your observing time, you should have a selection of accessories available to assist you.
“DO” use a star atlas or periodical magazine to help you locate planets and celestial objects.
“DO” have a good selection of eyepieces and optical filters at your disposal. Experiment a lot.
“DO” try to go out with more experienced observers. Learn about their equipment and observing techniques.
“DON’T” expect to see anything by just pointing your telescope anywhere.
“DON’T” use anything except a red light to read or see while observing. Any light, except for red, will minimize your night vision.
“DO” observe with both eyes open. This avoids fatigue at the eyepiece and prevents development of a lazy eye. If you find this distracting, cover the non-used eye with your hand or a patch.
“DO” use averted vision on faint objects: the centre of your eye is the least sensitive to low light levels. When viewing faint objects, don’t look directly at it, instead look slightly to the side, and the object will appear brighter.
“DON’T” expose your eyes to anything except red light for at least 30 minutes prior to obseving. This allows the pupils to expand to their maximum diameter.
“DON’T” look sideways into your eyepieces. Your eye is just another lens in the optical system. Keep it aligned.
“DON’T” use eyepieces that give a magnification less than 1.4X the aperture of your telescope in cm. At less than this magnification, the exit pupil of the eyepiece will exceed the entrance pupil of the best eyes.
When the Sun goes down, the Earth starts cooling off. Even in the summertime temperatures can drop, and combined with any moisture in the air, you can quickly get a chill or get cold. Remember to always bring a sweater or jacket with you.
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