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Wednesday June 28th 2017

Observing Tips for Beginners

 

Amateur AstronomersAmateur astronomers have to face some challenges with equipment, weather and environment during their stargazing sessions. The tips listed below help to overcome some initial hurdles and make the celestial night show even more exciting. If you have further tips, please contact us. We will be glad to share them with our fellow amateur astronomers.

Finder Alignment

Some telescopes come with finderscope others with red dot finder. Either way, the finders need to be perfectly aligned with the telescope axis. Alignment can be carried out during the day. Point your telescope at a stationary object far away. A chimney, an antenna mast or a mountain peak will serve well. Move the telescope so that the object is exactly in the middle of the eyepiece view. Lock the telescope in that position: Re-check if the object is still in the middle of the view. A adjust the finderscope / red-dot-finder by turning the adjustment screws so that the cross hair / red dot is exactly on the object. Do not compromise. Time spent for propper aligning means less time searching objects and more time observing fascinating objects.

Finding Objects with Finderscope / Red Dot Finder

I look for objects with both eyes open, one directly aimed at the object, the other through the finder. One has to get used to this way but once acquainted with it, objects are found much easier. Using the finder view with two eyes provides not only a small cutout of the sky but you can see a large part of it.

Magnification

Most telescopes come with one or two eyepieces. If you have more than one, start your search for objects always with your lowest magnification (the eyepiece with the largest focal length). The longer the EP focal length, the wider the field of view and the easier it is finding objects. Once the object is centered in the eyepiece, you can increase magnification with shorter focal length eyepieces.

Stay Warm

Besides setting the equipment up, stargazing is really not a very physical activity. Due to the excitement about celestial objects it is ofter forgotten that our body can loose temperature – quite quickly that is. Make sure to wear sufficient layers of clothes to keep you comfortably warm. The winter, nights in the desert or at high altitude remind us permanently to stay warm, but it can become very cold during a night after a nice, warm day in Spring or Fall. Check the weather forecast for the night. Take particularly windchill factors in account and dress accordingly.

Dew

How does dew form? The dew point is the point at which the air is saturated with water vapor. Warmer air is able to absorb more water vapor than colder air. If the air it cools down, excess water vapor has to go somewhere. On a greater scale, it will rain, on a smaller scale, exposed objects get wet.  Whenever air cools down our equipment cools down as well and the exposed surfaces radiate excess heat. As this happen, moisture condenses at a greater rate than that at which it can evaporate, resulting in the formation of water droplets.

Moist lenses disturb the view significantly. Because they have their mirror deep down in the tube, Newtonian telescopes are relatively save, but all other types of telescopes, including binoculars are unfortunately susceptible to dew. A simple but a little bit cumbersome trick is to point the telescope downwards between observing sessions. When pointing it down, it is more difficult for the radiated heat to escape, and lenses will keep their temperature longer; and with that, they stay longer moist free.

Another defense against dew are large(r) dew shields. Most telescopes come with some dew protection but these shields are often far to small. Larger dew caps are available for every telescope but they can be be made easily with readily available material. Dew shields delay dewing, unfortunately, they cannot prevent it completely.

When the telescope gets moist, take utmost care when de-fogging the lenses. Best is not to touch the lenses at all, especially when they are coated. A fan is often the preferred option. If you have to use a cloth, take a very soft one. Do not rub, only dab the lens to make sure the lens coating is not damaged during cleaning.

Heating telescopes with special telescope heating bands is most convenient. These dew heaters keep the telescope just a bit warmer than the air temperature and with that, preventing dewing and moist surfaces. Heating bands need however a 12 V power source, and they can draw quite some current.

If you bring telescopes from the cold into the warm, lenses will moist almost immediately. Do not put the protection caps on right away, wait until the lenses are completely moist free.

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