One thing to accept,
PEOPLE WILL TOUCH YOUR TELESCOPE, no matter how many times you say not to touch it, some will. If you are lucky enough to have more than
one scope, choose something large enough to give a nice image but that is also portable and manageable. If your scope
is too large, you will probably be asked to leave. We use dobsonians primarily, because they are public friendly, meaning
it’s pretty hard for someone to really damage the scope and well, because that’s all we have. Since not
on tripod, they are sturdy, easy to adjust and they aren’t delicate. They are hard to trip over and even harder to tip
over. Also, Newtonian reflectors are good because the optics are all far inside the tube, “its difficult for a kid to
get ice cream on the primary mirror of a reflector”. An 8” or 10” reflector is a good choice for side
observing. But, use what you have, even if it’s a tiny reflector, it can show the Moon nicely. Don’t let your scope keep you home.xx
Just about any telescope you have will
work well for public astronomy. If your telescope can track objects in the sky, that can be a plus, since you will not need
to readjust the scope between viewers to track objects. This does not bother me, but it definitely is an inconvenience for
some people. Also, a smaller scope, or one with an eyepiece close to the ground, is good for youngsters who are often too
short to look through a larger scope without help.xx
We suggest a 17
-25mm with our 8-10 dobs, because about 5 people can look before you have to adjust the scope and since you are usually looking
at the Moon, this is high enough power. Higher powered eyepieces work if they have a really wide field of view. Remember,
you won’t have any power on the sidewalk, your scope will ”run on potatoes” so if you have several eyepieces,
you might want to do a few tests and see how often you have to adjust your scope. Of course, if you have one eyepiece, whatever
size, use it.
We don’t usually use filters or barlows, mostly because we don’t like to carry a lot of stuff
with us and kids/public love to be blinded by a big, bright moon. For the public, ease-of-use usually trumps fine optics.
Choose an eyepiece with magnification that frames the subject well, and that has lots of eye relief. This makes it easier
for people to acquire a view through the eyepiece. I tend to use longer focal length Plossl eyepieces, along with a Barlow
lens to increase the magnification when needed. You can use fancy eyepieces, but keep in mind you will be cleaning them afterwards
– they accumulate a good amount of grime from eyelashes, makeup, etc deposited by your guests. You might consider devoting
a set of inexpensive Plossls, plus a Barlow, for public astronomy. This saves your “good” eyepieces from wear
and tear due to excessive cleaning.
You may want to provide additional light baffling in your scope in a city environment, to keep out stray
light from headlights and streetlights. People often mistake finderscopes for the actual eyepiece, and try to look through
the finder instead. If the finderscope isn't important for balance, remove it and use either a telrad/red-dot finder or the
GOTO feature of your scope to locate objects. xx
Step stools, ladders etc.
Depending on your
scope, you’ll probably need at least a step stool or small ladder for the kids. If your scope isn’t too
tall, a small step stool works best because if you are looking at something low in the sky, older people can sit on it.
Walkers are great. You can
usually find them at thrift stores or surplus medical supply stores. Placing the walker in front of the eyepiece lets people
know where to stand and it gives them something besides your scope to hold on to.
You should always have flyers available with information
about what you are observing, the Sidewalk Astronomers, your local club and your contact information. You can also have flyers
that advertise upcoming club events, sky information, or pictures/puzzles for kids. Many astronomy magazines and NASA have
handouts for getting started in astronomy and you can download and copy them.
It is also a good idea to have a couple of black and white
large photos of what you are viewing. This way, the public gets an idea of what they should see and can tell you if the scope
is out of focus or the image and passed from view.
Another good idea is to have a photo of the night sky taken from a dark location so
that you can show the public how the sky SHOULD look without the massive light pollution in our cities.