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THE ASTRONOMICAL LEAGUE'S
URBAN CLUB
Rules and Regulations
List of Objects
Tips for Urban Observing
Tips for Observing in Light Polluted Areas
By
Ken Boquist, Bill Geertsen, David Hasenauer, Lee Maisler, Chris Randall, Roberto Torres, John Wagoner
Sometimes it can be difficult observing in heavily light polluted skies.
But by following a few procedures, your observing session can be more enjoyable
and more rewarding. The following are tips that our crack team of observers
offered to help increase your satisfaction when observing in light polluted
areas.
When to Observe
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Observe during new moon. Just like observing in dark skies, the moon adds
light to the night sky and reduces contrast.
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Observe after 10:00PM. This gives the dust and water in the air a chance
to settle. Dust and water reflect light which can turn a good night into
a bad one.
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Observe after 11:00PM. Many stores have closed by this time, and because
they turn off their lights, a city's light glow is reduced considerably.
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Observe after 1:00AM. After the stores have closed, most shoppers and workers
have gone home which means that there is a lot less traffic on the streets
and freeways, and light pollution is reduced.
-
Ask your neighbors over for an observing session. After seeing the effect
of light pollution on observing, they will be more co-operative in turning
off their lights for you.
Observing Hints
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Try to catch your target objects straight overhead. This is always the
darkest part of the sky.
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Select the right objects to observe. Magnitude is not everything. A bright
galaxy may be invisible, whereas a dim planetary may be easily seen. Small,
high surface brightness and stellar objects are easier to observe than
large, diffuse objects.
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If you have an alt-azimuth mount (Dobsonian), try to observe near the meridian.
Up-down, left-right motions translate into north-south, east-west motions
and makes following a path on a star chart easier.
Watch Sky Conditions
-
Pay close attention to the weather. Cool, dry nights are best at any location,
but are more pronounced in the city.
-
Learn to read the quality of the sky by the observing of stars with the
naked eye. A clear night might seem perfect for observing, but may in fact
be bad for viewing if the seeing is not good.
-
Observe after a rain storm. The skies appear darker as light is no longer
reflected off of dust particles in the air.
-
Observe after a cold front has come through. The air is more stable and
the air pollution has been blown out.
Observing Techniques
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Use a dark cloth to cover your head and eyepiece to shield them from stray
light.
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Use a dew shield on your telescope to shade it from stray light.
-
Clean and collimate all optics. Dirty optics scatter light.
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Light pollution and O-III filters are good for planetary and emission nebulae.
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Use a pirate's eyepatch to keep out stray light.
-
A right-angle finder with amici prism under a dark cloth is helpful for
finding objects.
-
Setting circles are a great aid for finding difficult objects, especially
when those objects are quite some distance from a naked eye star.
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A good star atlas, a pair of binoculars, and a one power finder (e.g. Telrad)
with a template for that finder, are inportant for finding objects in bright,
non-contrasty skies. Telrad-hopping can sometimes be easier and just as
useful as star-hopping with a finder. Viewing the sky through your Telrad
with binoculars is also a nice trick.
Observing Location
-
Pick the darkest section of your site and make an extra effort to block
out stray light. Using a light baffle made of a tarp and tent pegs help,
as well as a three-sided wall made out of cardboard. Try to make the immediate
area around your site as darkened and non-reflective as possible. Use existing
structures and foliage to block the direct view of lights.
-
Use earphones or a radio to mask neighborhood noise. Noise can be very
distracting.
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Finally, attitude is very important. Any observing is better than no observing
or TV.
[ Home ] [ Binocular Messier ] [ Binocular Deep Sky ] [ Double Star Club ] [ Urban Club ] [ Lunar Club ] [ Universe Sampler ] [ Planetary Observers Club ] [ Asteroid Club ] [ Southern Skies Binocular Club ] [ New AL Observing Programs ] [ Arp Peculiar Galaxies ] [ AL Observing Program Contact Info ] [ Observing Forms and Sketch Log ]
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