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...

An Internet Telescope Tutorial
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2002Feb14