THE INTERNET TELESCOPE -- THE GUTS OF IT
Optics/Mounting/Camera/Limitations/Next Steps...
OPTICS:
The internet telescope is a C-14 f/11 telescope mounted
on a Paramount and located near Mayhill, New Mexico.
C-14 refers to a 14 inch aperture Celestron(c) make Schmidt-Cassegrain
style
telescope, featuring a spherical primary mirror and corrector plate lens
in front. You can visit website: http://www.celestron.com/schmidt.htm for
details. The 14 inch diameter and f/11 specification tells us that we
have 14 * 11 = 154 inches of total focal length. With a one inch
eyepiece, this would give a 154x magnification. However, it's hard to
share the view that way, so we use a digital camera, called a CCD (charge
coupled device)
The Paramount(c) is the smart box that holds the telescope and talks to
the computer for precise pointing and tracking of the astronomical
objects. For details about this, you can visit
website: http://www.bisque.com/Products/Paramount/NewMe/default.asp
DIGITAL CAMERA:
This item is not unlike a digital camera you may have seen or used: it has
a light sensitive chip called a Charge Coupled Device (CCD) array that
collects light and makes a mosaic image from individual "picture
elements" or pixels. Unlike your digital camera, this one has a shutter
with controllable exposure lengths. That allows us to go for long
EXPOSURES of many minutes. The digital result, once processed, can be
manipulated in many ways to detect many things captured in the image data.
There are LIMITS to exposures -- more than ~10 minutes will result
in extra dark current noise in the pictures. You can always add a
series of shorter exposures.
Not great for planets -- this is a
relatively short focal length telescope and the planets appear quite small
on the digital camera.
The "equatorial" mount: aiming it via
coordinates:
The Paramount device is a smart clock that translates your request
to point at a particular object (review NOMENCLATURE in the
previous webpage) and moves the Paramount and telescope to the
correct aim on the sky so you can take your picture.
Limitations:
1. mechanical:
The Paramount cannot turn 360 degree circles without winding up its
internal wires. Being a German Equatorial style mount, it also has to
avoid crossing the meridian. This means long exposures near the
meridian may be interrupted. Simply wait for the object to cross and
return 30 minutes later. Also, right after a slew, it may take a few
seconds for the mount to settle. Try a short picture first and make
sure it hasn't shown streaks.
2. optical/site and weather:
There is no point in aiming the telescope below the horizon; you will see
nothing. While the site is dark and away from light pollution, it still has occasional
clouds and observing time might be limited. When the moon is bright
and nearly full, extra light can creep in and affect the image as
well, making it harder to see faint galaxies and nebulae sometimes.
3. A few other things:
SEASONALITY-- not all objects are above the horizon
at night all year long. Just like the seasons, some
constellations are available only during certain
times of year. Study the skymaps to come to decide
which and when. Here's a short table to help you:
Season/Month Sidereal time at Meridian constellations
8pm local
Feb 6 hours S.T. Orion
March 8 hours S.T. Leo
April 10 hours S.T. Virgo more to follow...
Need a star map? Email rstencel@du.edu with name and mailing address for
one.
DISCONNECTS -- happen. If your internet connection dies during
an observing session and you still have /meridian avoidance...