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Monday, December 8, 2008

Cold Weather Astronomy Tips

Icy Zhumell 10For most astronomers, half of the observing year is spent in cold weather. Family and friends may think you're crazy, and sometimes you might agree. The problem is, some of the best deep sky objects are visible only during winter. Take for example, M42, the Orion Nebula. Orion rises high into the sky during the coldest parts of the winter. In Ohio, where I observe, the coldest nights are usually the clearest too, with excellent transparency and seeing that is marginally better than our usually bad seeing. So in order to take advantage of these great winter deep sky objects and my better atmospheric conditions, I have to venture out into the snow and the cold. I've learned a few things about keeping warm at the telescope in my time under the cold Ohio sky, and I'll share them with you here. At top right, you can see a picture I took of the secondary on my Z10 dob. The whole scope was covered in frost, but my mirrors were still clear, so I kept on viewing! You can keep on viewing too, if you follow these tips to stay warm!

  • Dress in layers. This will help to keep your body heat in, and keep you comfortable for hours. I usually wear a T-shirt, a hoodie, and a heavy winter coat. When it gets real cold out (below 0° F) I will substitute the winter coat for a pair coveralls, much like a snowmobile suit.

  • Also, wear good boots. The best boots will have a material called Thinsulate in them. Thinsulate is one of the best insulating materials out on the market right now, and believe me, it keeps me warm both at the scope and in the woods during deer season. Thinsulate boots usually are rated in grams of Thinsulate. The more grams, the better and warmer the boot.

  • Good gloves are important too. Good gloves for astronomy are hard to find, though. The problem with huge gloves is that you won't be able to work the focuser accurately, or handle those expensive eyepieces. I prefer a glove that is made for hunting that has a flap so you can remove your fingers from the glove quickly and easily. That way you can still use your focuser, then keep your hands warm when you're done. You can also get Thinsulate gloves.

  • Stay out of the wind. Wind-chills can make the difference between feeling 30° F and -30° F. See this with the following wind chill calculator. Set up your telescope near an object like your house or a hedgerow. While this may limit your view of certain portions of the sky, some planning here can keep you much warmer.

  • Use chemical hand-warmers. HotHands is a good brand, and can be found at any store like Wal-Mart or the likes. Once you open the package, the oxygen starts a reaction that heats up the hand-warmer. These little things are great, put them in your pockets, in your gloves, and sometimes even in your boots!

  • Rubber band a hand-warmer to your Telrad. The Telrad is almost always the first thing to be covered in dew or frost. Using a hand-warmer will help to keep it useable.

  • Take breaks. Every hour or so, when it seems like you can't take the cold anymore, go inside and warm up. Get some coffee, sit down, and relax. It helps to get the blood flowing back to your extremities and makes longer viewing sessions possible.

  • Keep moving around. When I'm observing in the winter, I tend to spend less time on each object and move the telescope around quite a lot. This definitely helps to keep you warm.

  • If you use a green laser, keep it warm. Lasers, and electronic devices in general start to lose a good bit of performance in extremely cold weather.

Using these tips, you can make your cold weather observing sessions more comfortable and safer. Frostbite is the enemy, but as long as you keep your fingers and toes warm, you won't have to confront it.

Clear skies!


RevAaron said...

Good tips. For me in Florida, I relish these cold nights. My rule: call it quits when you lose sufficent feeling in your fingers to write notes. I honestly don't know how you people in northern latitudes do it :-)

Anonymous said...

how many hours during the night do you view anyway? sounds like quite a few. dude!! that's cold stuff.

Sean Welton said...

Haha, I rarely get clear nights during the winter, so when I do get a clear night, I tend to stay out for a while!


December 10, 2008 at 12:25 AM

Mike Simonsen said...

Good tips, Sean. I can totally relate. I placed this article in the AAVSO Writers Bureau for December.

David Brown said...

For the boots I suggest the toe warmers, designed for a low oxygen environment.

Anonymous said...

I recommend you use a military sleeping bag.

The German military have good bags with sleeves and also Snugpak do very good military bags but they do get expensive if you want bags for -50º C (Antarctic). Military bags have hoods also.


Always use military bags with a centre zip if you live or observe in a dangerous area where you may need to exit the bag with speed for any reason.

Military bags are designed with emergency exit in mind so a centre zip is favoured.

Waxing zips helps them run smoother, I use a bar or tin of Nikwax because it is waterproof but you could use Bees wax to achieve the same smooth zip action.

Anonymous said...

The best tip for sensible boot use is to make sure that your boots are not tied too tight because in cold conditions your blood can’t flow so easily thus you get cold feet. You remedy this by making the lace slack across the instep of the boot.

German military boots have a lace hook type design on the instep of the boot and the rest of the boot is lace Eye type design. The laces can be easily removed from just the instep hooks to aid blood flow in cold conditions. This lace hook type makes it very easy to adjust the bootlace tension with minimal effort, even with cold hands. The main advantage of the hook is that you don’t need to undo the entire lace and the lace can be replaced in the hook in the same way.

Keep your boots clean and wax them because dirt will help the loss of thermal retention and is bad for the health of the boot leather. Use a good lace (4 to 5mm Military Para cord is best) I have had the same laces for many years. Use a good water proofing wax on all of the boots stitching (applying it with a medium-hard toothbrush gives the best results).

Two pair of socks for warmth.
The first is a thin thermal sock that is a snug fit and the second is a good quality wool calf high boot sock that is a loose fit (I use a fibre mix of 60% – 40%).
The 60% is wool for thermal retention and 40% acrylic for shape retention also faster drying times when wet.

I would like to try Sealskinz socks but they are way overpriced. http://www.sealskinz.com/

Anonymous said...


The Wet can be FATAL in Cold weather especially with a wind chill.

You lose 30% – 40% body heat through your head so a good thermal hat is very important.
Natural fibres are warm but take a long time to dry and artificial fibres are just as good unless you live in the Antarctic Circle but take less time to dry.

Gloves are very important because if your hands do not function you could be in a lot of trouble in some outdoor situations. Shooting Mitts (a full mitt) are the best for warmth and there are some very good makes on the market.
Some have a design where you can release your fingers from a slot in the palm of the glove. This is very useful for doing little jobs that need dexterity of touch with the fingers.

It is critical to keep your clothes loose in the cold weather but well fastened.
Make sure that all your layers of clothing are dry and loose because you will lose heat pockets if you have them on too tight.

Sitting still will also loose heat so don’t stand directly on the ground if it is very cold or stone under foot. Use cardboard or a thick piece of carpet or a box filled with insulation fibre to stand on.
Sit at the telescope in a sleeping bag, with military bags you can sit or sleep in them with your boots still on.

Eat well and drink plenty of warm fluids because the cold dehydrates you. Coffee also dehydrates.
Eat carbohydrates such as porridge, before you go out, as this will keep your body temperature up and takes less effort to digest than other foods saving your energy to keep you warm.

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