The Space & Beyond Blog
A beginner’s guide to observing:
15 tips for using your new telescope
Utilize this guide to observing to start navigating the night sky like a pro.
By Michael Bakich
Astronomy can be a challenging hobby to dive in to, so here is a guide to observing to help you get the most out of those precious moments behind your new telescope. I’ve discovered some of these tips on my own, but others were passed on to me by wise observing buddies. Read them, use them, and add this guide to observing to your repertoire — because if you do, I guarantee you’ll become a better observer.
ADJUST TO THE DARK
Dark adaptation is the process by which the eyes increase their sensitivity to low levels of illumination. In the first 30 minutes, sensitivity increases 10,000-fold, with little gain after that. But brief exposure to bright light temporarily rolls back this hard-won increase. Just how much dark adaption you lose depends a little on the intensity and a lot on the duration of the light. A single flash from a strobe does less damage than a bright light lasting a second or more. At night, your eyes are most sensitive to red light, which means that for a given brightness, you’ll see more using this color. Use a red flashlight, adjust its intensity to the lowest usable level, and then only use it to gaze briefly at the object it illuminates.
AVOID EYE FATIGUE
Take short breaks during your observing session and try a simple eye exercises every 20 minutes or so. For example, lightly cup your eyes with your palms and relax for 60 seconds. Or simply look away from the eyepiece and roll your eyes up, down, around, and side to side for 20 seconds; then relax with your eyes closed for another 30 seconds.
WEAR AN EYE PATCH
Many amateur observers place an eye patch over their observing eye while setting up equipment. Put it on as long as possible before you start your session. You’ll be rewarded with a fully dark-adapted eye when you’re ready to begin observing. Then, move the patch to your non-observing eye when you look through the eyepiece. This lets you keep both eyes open, a technique that reduces eye fatigue.
DON’T SKIMP ON VITAMIN A
A diet deficient in vitamin A can lead to impaired night vision. An adequate intake of vitamin A from foods such as eggs, cheese, liver, carrots, and most green vegetables will help ensure proper visual acuity at night.
LEAVE THE ALCOHOL AT HOME
Don’t drink and drive the telescope if you’re looking to get the best out of your observing session. Why? Alcohol impairs vision.
SCOUT THE WEATHER AND SEEING
Some atmospheric factors indicate the quality of “seeing,” or the steadiness of an astronomical image. An air mass colder than the ground will produce puffy cumulus clouds and unsteady air, but it’s usually relatively free of dust. An air mass warmer than the ground will produce stratiform clouds, haze, or mist, and hold copious amounts of dust, but astronomical images will be steadier. Bad seeing is almost guaranteed at least 24 hours following the passage of a front (the boundary between warm and cool air masses) or trough (an elongated area of low pressure). Seeing can be very good with thin cirrus clouds aloft, but the opposite is true when high cirrus clouds combine with low-level crosswinds.
COMBAT THE COLD
For low-temperature observing, preparation is everything. Over pack. Most heat loss occurs from the head, so keep yours warm. Heat also will seep into the cold ground through your boots. Hand warmers are superb but never seem to last the full time specified on the package. Keep warmers in your side pockets and slip them in and out of your gloves or mittens for quick warm-ups. Finally, dress in layers. For more tips on what to bring for your first night under the stars, reference our stargazing packing list.
KNOW YOUR LIMITING MAGNITUDE
No better gauge of observing-site quality exists than a direct measurement of limiting visual magnitude, or LM. Most observers determine their site’s LM by identifying the faintest star they can see, usually near the zenith — or the point in the sky directly above them. Others use a method devised by meteor observers, who count the number of visible stars within predetermined asterisms.
CONSIDER OBSERVING CHAIRS AND LADDERS
If you’re at all uncomfortable at the telescope, you’ll do less observing, and the observations you make will be less fulfilling and less accurate. In my opinion, nothing says comfort like a high-quality observing chair. Such an accessory has four main features: sturdy construction; a padded seat; easily adjustable height; and back support. Observing chairs work fine for refractors and Schmidt-Cassegrain telescopes, which have eyepieces at the lower ends of their tubes. For large Dobsonian-mounted scopes, however, a ladder of some type is usually necessary. I suggest buying a three-step folding utility ladder with a tray. Such ladders usually feature wide, rubber-coated steps and the tray is a real bonus when you need to change eyepieces or filters.
PLAN YOUR CELESTIAL ATTACK
Write a few questions on index cards before your observing session. For example, a card for planetary nebulae might have these questions on it: Can you see the central star? At what magnification? What shape is the nebula? Is any color apparent? And so on. Questions will jog your memory and remind you to look for certain common details — especially when you’re tired and not necessarily at your peak.
FOCUS YOUR CAMERA
Astroimagers want their lenses focused at infinity, but newer autofocus lenses can be focused past infinity by hand. To resolve this problem, set the lens at infinity during the day and then lock it there with one or two wraps of tape around the barrel. Use tape that won’t leave a residue (no duct tape). Manual focus lenses don’t have this problem, but some astrophotographers tape them anyway. Color filters can also help you observe planets easier because they exaggerate brightness differences (contrast).
BE ON THE LOOKOUT FOR TUBE CURRENTS
Tube Currents degrade telescopic images, but how do you know if you have a problem? Check the out-of-focus image of a fairly bright star. If you see lots of circular motion inside the star’s image, you have a severe problem. The best solution is a small, low-flow fan to move warmer air out of the telescope tube and quickly bring your mirror to the same temperature as the ambient air.
RECORD YOUR OBSERVATIONS
I have maintained a detailed observing log for decades. My instrument of choice is a digital recorder. Many of my observing friends write out their observations either in a logbook or directly onto a star chart, a method that allows for sketches as well. I speak into my recorder at the telescope and transcribe the observations later, usually the next day.
TRACK DOWN THE DEEP STUFF
When you’re observing celestial sights at the limit of your vision or looking for small details in bright astronomical objects, use a technique sometimes called “rocking the scope.” Gently tap the mount or the telescope tube so it momentarily wobbles. It really helps faint details pop out!
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With this guide to observing you’ll be ready to start navigating the night sky in no time! Make sure to keep an eye on upcoming celestial events so you know what to look for.