The 24 Inch McMath Telescope

This photograph shows the 24” McMath Telescope.

Bernard Friberg (observatory director at the time this photograph was taken) is standing along the south wall of the building. (The walls lie approximately along north, south, east and west axes.) The following can be seen in this photograph:

• The declination drive is dark but visible in the center of the photograph.
• The right ascension drive is hidden behind the declination drive.
• A small telescope is visible on the right.

This photograph shows the telescope as it appears when pointing toward astronomical objects; the primary components of the telescope are visible:

• The 6 inch refractor is the tube above the main telescope.
• The declination drive is the black cylinder located on the lower right (it is easier to see in the following photographs).
• The right ascension drive is the black circle on the lower left (it is partially obscured by the rest of the telescope and has several circular cutouts, it is easier to see in the following photographs).

Positioning the telescope requires the movement of approximately 1000 pounds of metal and glass. The telescope is balanced; positioning it does not take much effort.

The roof has been opened (otherwise the telescope could not be pointed upward) and two small telescopes can be seen behind the 24 inch telescope.

Another view of the telescope.

The 6” refractor can be seen on the right side of the 24” telescope tube.

• The eyepiece for the 24” telescope is on the far left center.
• The eyepiece for the 6” refractor is on the left center (to the right of the 24” telescope eyepiece).
• The black box mounted on the 6” refractor is the Telrad. (This is a device that produces a “bullseye” pattern that is helpful in aiming the telescope at a particular object).
• Above the 6” refractor is a finder telescope.
• The focus knob is located below the 24” telescope.

This photograph shows the declination drive and right ascension drive of the McMath telescope. The components shown are:

• The wheel at the lower left is the right ascension drive.
• The disk at the upper left is the declination drive.
• Near the center of the photograph is the NGC-MAX (the small rectangle with a red display). This is a small computer that tracks the position of the telescope.
• The telescope tube itself is only partially visible (along the right of the photograph). It extends to the right of the photograph (it is more clearly visible in the previous photographs).
• A small white telescope is visible behind the 24” telescope.

This photograph shows another view of the telescope.

The small box near the center of the photo is the NGC-MAX.

This photograph shows the components of the 24” telescope.

1. The right ascension drive moves the telescope to compensate for the earth’s rotation. (Depending on your monitor, you may find this large dark circle difficult or impossible to see, but it is there.) It is possible to use the right ascension drive to position the telescope along the polar axis: This is accomplished by slowing down or speeding up the drive motor for a few seconds.
2. The declination drive mechanism contains a motor that allows the telescope to be moved slowly along an axis perpendicular to the polar axis. It also acts as a counterweight.
3. Light from stars and other astronomical objects passes through the opening at the upper right.
4. The light passes down to the primary mirror.
5. And the light reflects back to the secondary mirror.
6. Finally the light reflects back to the eyepiece. Note that different size eyepieces can be used and the size of the eyepiece determines the magnification of the objects.