From: Guy Nason [gnason@rogers.com]
Sent: Wednesday, January 24, 2007 4:10 PM
To: Dunham, David
Subject: Re: Web site for cold weather observing information?

Below is a column I wrote for JRASC (published Dec. 2006). 
I don't think they'd mind if you used it. :-) 

Guy
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Carpe Umbram [Seize the (occultation) Shadow]: Baby it's cold outside!
(#5: Revised 2006-10-16 for the Dec. 2006 issue) 
Guy Nason Toronto Centre asteroids@toronto.rasc.ca

She: I really can't stay
He: Baby it's cold outside
She: I've got to go away
He: Baby it's cold outside
She: I really can't stay
He: Baby don't hold out

Both: Ahh, but it's cold outside

-- From "Baby It's Cold Outside".
Words and Music by Frank Loesser 1949

I like to think that the woman in the song really can't stay because 
she has an occultation to time. But it is cold outside this time of 
year, so she'd be wise to take suitable precautions. She should 
remember that Mother Nature does not suffer the unprepared kindly. 
(If you doubt this, read Jack London's short story To Build a Fire.) 

If you decide to time an asteroidal occultation away from home one 
of these fine winter nights - or undertake any other activities in 
the wild, for that matter - please prepare both yourself and your 
equipment appropriately. To many of you experienced winter-time 
observers, this will be "old hat", but I hope that those new to 
remote winter observing will take to heart the following advice and 
act accordingly. The rest of you might treat this as a review. 

Personal comfort and safety.

If possible, always use the buddy system. Two people are better than 
one and can assist each other if necessary. In the case of an 
occultation event, I suggest that observers team up and either 
observe together, or nearby each other, perhaps a kilometre or two 
apart to avoid duplicating each other's efforts. Take at least one 
vehicle per station. It's your shelter and means of escape - your 
lifeboat, if you like. Take cell phones along if service is 
available. CB radios and FRS radios are also useful. Before you head 
out, give your phone number to someone at home and tell them where 
you are going and when you will return. 

Dress warmly. The rule of thumb is to dress for 10 degrees colder 
than the forecast wind-chill factor. See chart. You will not be 
physically active once your equipment is set up, so you won't be 
generating as much body heat as you would if skiing or snow-shoeing, 
for instance. Cold is the enemy and wind and moisture are its 
agents. Dress in layers and pay close attention to your feet, hands 
and head. The layer closest to your skin should be a “wickable” 
material such as wool, polypropylene, polyester or even silk. 
"Polypro" long underwear should be worn whenever the temperature is 
below freezing, and even if it's a few degrees above. It will pull 
moisture away from your skin and into the next layer where it can do 
no damage. Your outermost layer should be wind- and water- proof‘, 
but “breathable”. Goretex is good. For all layers, avoid moisture-
retaining cotton. When it gets wet, it stays wet and will bleed 
moisture into all it contacts. 

During the travel phase, shed some of those layers so you don't 
overheat in the car. Then don them as necessary when on-site. This 
will minimize sweating. I find it best to be just slightly cool, but 
not cold. If you begin shivering, stop what you're doing and seek 
heat immediately. Shivering is the first sign of hypothermia - the 
lowering of the core body temperature - and is not to be taken 
lightly. If you begin to shiver, abandon the enterprise, stow your 
gear, and go somewhere warm. A couple of other hints to keep you 
comfortable: take along a small piece of carpet to stand on (or, if 
sitting, to rest your feet on). A Thermos flask containing a warm 
drink (no alcohol!) is also a good idea. In very cold weather I wear 
light gloves inside heavy mittens. I pull off a mitt to make fine 
adjustments to my equipment, then promptly reinsert my gloved hand 
back into the mitt. Never touch freezing metal with bare skin! If 
you do this you will become instantly stuck. Do not try to pull away 
or you will leave skin behind. Instead, warm the metal until you are 
released. 

Your vehicle.

Be sure you have a full tank of fuel before you arrive on-site. 
Late-night service stations are rare in rural areas and running out of 
gas could be fatal. In very cold weather you might want to keep your 
engine running. If so, be sure the tailpipe is clear of all 
obstructions, open a window slightly, and keep the exhaust well away 
from your telescope and line of sight to the target star.

Of course, your car, van or truck must be equipped for winter and in 
very good condition: winter tires (tire chains for those of you in the 
Rockies and perhaps elsewhere); strong battery; properly inflated spare 
tire; jack and tire iron on board; etc. A winter survival kit is always 
essential, not just for occultations. It should contain: a shovel; a bag 
of traction aid such as sand or kitty litter; booster cables; 
flashlight with fresh batteries; first-aid kit; safety triangles or 
flares; a tow-rope; a heat source (Sterno or candles); matches; duct 
tape; basic tools; and a fire extinguisher.

Your Astronomical Equipment.

In general, telescope optics are not adversely affected by extreme cold, 
once they reach ambient temperature. However, moving parts and 
electronics are. For moving parts such as focusers, gear trains and axle 
bearings, the major problem is the lubricant supplied by the 
manufacturers. Only Russian manufacturers such as Intes pay any 
attention to designing their equipment to operate in the cold. If you 
use your telescope at temperatures near or below freezing, it’s a good 
idea to replace the stock lubricant with grease designed to perform well 
at sub-freezing temperatures. One such lubricant is Dow Corning's 
Molykote 33 Extreme Low Temp. Bearing Grease, Light. It's a 
phenyl/methyl silicone grease with a lithium thickener that is rated for 
use from -73 deg. C to +208 deg. C (-100 deg.F to +400 deg.F). It's 
available in small 180 gram tubes and larger containers. For more 
information, visit: 
http://www.dowcorning.com/applications/Product_Finder. 

LCD displays do not like the cold at all. If your telescope is so 
equipped, you’ll have trouble reading any message that crawls across the 
screen because of the prolonged decay times of the on-screen characters. 
The only way to beat this is to keep the controller warm. A chemical 
hand-warmer rubber-banded to the back of the hand controller should help.

Batteries can cause serious grief in cold weather. Make sure that all 
your batteries are fresh and/or fully charged and keep them as warm as 
you can. Use new alkaline batteries in flashlights, radios and tape 
recorders. Use heavy-duty deep-cycle batteries for more demanding 
equipment such as motor drives, TV/VCR combo units and dew remover 
systems. I suggest activated glass-mat lead-acid batteries for these 
more demanding tasks. They are heavy but robust and spill-proof. 
Lead-acid and gel-cell batteries lose considerable capacity as the 
temperature drops. Typically, at 0 deg.C such batteries are working at only 
80% of their nominal capacity. At -20 deg.C power is reduced to 60%. 
Therefore, use the highest Amp-hour rated batteries you can lift. A word 
of caution: avoid using your vehicle battery. No matter how successful 
your observations, you won't be very happy if your car won't start 
afterwards. Another tip: put batteries in a picnic cooler, activate a 
couple of chemical-type hand-warmers, toss them into the cooler and 
close the lid. Warning: Never use lighter fluid warmers or other devices 
that use an open flame anywhere near batteries! Batteries emit hydrogen 
and could explode if brought near a flame! Flying shrapnel and 
hydrochloric acid aren't things you want to experience.

Cables are the most common cause of electrical failure in the cold. 
Bring extra cables for every task and be sure that they are in good 
condition. Wires get very stiff in sub-freezing conditions, so try not 
to move them once they are in place and operating properly.

Allow Extra Time.

Aside from personal safety, this is perhaps the most important piece of 
advice for cold weather observing. Everything takes longer in the cold. 
There is extra gear to prepare and load. You need time to get into cold 
weather clothing on site. Equipment set-up is slower and connections 
require more rigorous testing. Things will go wrong much more 
frequently, requiring extra time to rectify.

I hope this helps all you occultationists and other hearty observers to 
have safe and successful observing sessions. Remember above all to take 
care of yourselves and your fellow observers. No data are worth personal 
injury – or worse. But with that in mind, don’t let Old Man Winter scare 
you away from clear dark skies. Just prepare properly when, Baby, it’s 
cold outside!

* * * * * * * * * * * * * *
The longer winter nights bring more occultation opportunities – so much 
so that it's impossible to list them all here for the next couple of 
months. Here are those I know of that involve stars of magnitude 10.0 or 
brighter. For finder charts and other details for these and other 
opportunities in your area, please visit Steve Preston's website at 
http://www.asteroidoccultation.com/ and Derek Breit's site for Google 
maps and station sorts at http://www.poyntsource.com/New/index.htm. As 
always, please drop me a line if you plan to observe and time any 
asteroidal occultations or if you would like to know more about how to 
observe and time asteroidal occultations. Good luck and clear skies!
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