About the telescope

The telescope is a 16-inch Meade LX200 Schmidt-Cassegraine telescope with an effective focal length of 4.064 m and an F-ratio of f/10.  The light passes from the sky through a corrector plate onto a concave primary mirror. The convex secondary mirror is located in the center of the correcting plate and focuses the light through a central baffle toward either the eye piece or the camera. 

The telescope is mounted in an equatorial fork mount. The base plane of the mount is parallel to the Earth’s equatorial plane. This plane is also the celestial equatorial plane, defining the celestial sphere. The position of stars, planets, and other sky objects with respect to the celestial sphere is not dependent on the observer position on Earth – therefore telescopes often are mounted in fixed equatorial positions. Then we only need two angles, called Declination and Right Ascension, and the local time and date to find any object in the sky reliably.

The celestial sphere is defined by the equatorial plane of the earth. Celestial longitude is called Right Ascension and measured in terms of 24 h. Celestial latitude is the Declination, measured in angular degrees.

The correcting plate is shaped to account for the spherical aberration of the mirrors. What does this mean? Both mirrors are shaped as sections of spheres. However, spheres do not reflect light into a perfect focus. You might remember how intro physics classes go through much ado talking about paraxial rays, rays close and parallel to the optical axis? A telescope uses all light, not only rays close to the optical axis. This leads to imaging errors for points away from the center of an image. The correcting plate bends light just right to correct for these imaging errors. 

In the summer of 2024, a new camera system was added to the telescope. The computer-controlled camera, filters, and guider system attaches to the back of the telescope to capture images of planets, stars, and deep-sky objects up to magnitude 15. The camera features a CMOS sensor, based on the common “complementary metal oxide semiconductor” technology in integrated circuitry. As opposed to the CCD (Charge-Coupled Device) technology used until recently in astrophotography, a CMOS sensor includes all the control circuitry, such as individual amplifiers for each pixel, in the same chip with the array of photodiodes used to collect the light (pixels). This gives the sensor a much faster processing speed than the typical CCD device. The 24 million photodiodes, size 3.76 micrometers, run in reverse mode similar to solar cells to collect the photons. Shorter exposure times are an advantage since it minimizes the image noise introduced through imperfect tracking.

History

under construction