Observation Tips

Tips and Techniques

Lateral Vision

I strongly suggest you do your deep sky observations like this. This technique consists of watching the object sideways, by looking next to it instead of directly at it. When you look next to an object, the light from that object hits the most sensitive part of the eye, so you can retrieve a maximum information from what you saw. You want to gather as much photons as possible.

Acclimate your Eyesight

It is very important to let your eye get used to nighttime before starting any type of astronomical observation. Otherwise your pupil does not have time to expand to its maximum size. This process takes about 20 minutes. However if you return in the meantime into bright light all will be lost immediately. During that time you can observe the milky way, the constellations, polar-aline your telescope or wait...

Cooling down your Reflector

Never ever skip this important part of preparation. A newtonian, because its tube is open to air, needs to cool down its inner temperature so that it is equal to the outside temperature. Otherwise you will have an unusable telescope. Turbulence is caused by the thermal exchanges between the air in your tube and the air outside it. You want to limit turbulence.

Red Lamp

Once your eyes are in “night vision mode” you must not return into light.
Our eye is not very sensitive to red light, however you can still see it. When you need light to find that lost eyepiece, to consult a map, or to know what time it is you turn that red lamp on and you won’t lose your eyesight. Paint your flashlight’s bulb with dark red nail polish. This will act like a filter and block all the rest of the light spectrum.

Collimation


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The Best times and seasons

Just after sunset, the earth is still very hot and infrared light is emitted by it. This is why I strongly suggest you wait till the sun is low under the horizon before starting to observe. The more you wait, the better the sky’s quality. Slowly the earth is cooling down. The best hours are early in the morning, around 4, 5, or 6 a.m.

This is also the reason why summer isn’t a good season for observations. The earth is very hot and takes longer to cool down, plus nights are shorter so you have to wait until 11p.m. before being able to start any observations.
However, in winter, it’s the opposite. The sun sets around 5 p.m. so you can start observations earlier. The earth doesn’t heat up too much so it takes less time to cool down which means that the sky quality, in general, is much better in winter. I encourage you to observe early in the morning, especially in winter. Trust me, you will see the sky as you never had before.
In a city some lights turn off after midnight (including this god damn Eiffel Tower revolving light.)

Snow and Mountains

A part from being only present in winter, the best season for observing, snow is very useful to an astronomer. It has an extremely low albedo and therefore does not cause turbulence due to infrared light. If you live in a mountainy region, put your telescope on a layer of snow. You will limit turbulence.

Most excellent sites are located on top of mountains. It makes it possible to weaken the astronomer's top enemy:the atmosphere. Plus you have snow there. The higher you go, the thinner the atmosphere, and the lower the negative effects it has on your observations. This is why Hubble, the space telescope was sent into space. One HST of 2m of diameter is equivalent to about three Keck-sized telescope, each one being around 10m in diameter. the atmosphere deforms and reflects light.

Planning


Be sure to plan your observations in advance. This means to know what you will be looking for: choose your objects, it's best no to mix planets and deep-sky. Never forget to check the moon phase if you are doing deep sky observing. Always check out the weather forcast, it's frustrating to find out that the night is cloudy when everything has been prepared carefully. Wind is also an important factor: it makes your telescope shaky. Here's a list of "To Do's" Before observing:

  • Put thick clothes on and bring a coat, gloves and earmuffs, even in summer. It gets cold pretty quickly.
  • Put your telescope out before sunset. Wait one hour minimum after sunset before starting your observations.
  • Things to bring: A red lamp (flashlight), a sky map, a thermos with coffee or hot chocolate, your webcam or camera if you plan on doing astrophotography.