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Bessie is a modified version of the original HI telescope, created by six undergraduate students who were interns at the Green Bank Observatory in conjunction with the First2Network. The six people involved in its construction were Garrett Basham, Lauryn Eldridge, Dylan Johnson, Matthew LeRoy, Nima ShahabShahmir, Abby Sine.

Materials List[edit]

  • 2x4 - 12 feet
  • 2x2 - 7 feet
  • Plywood
  • Reflective insulation or another mostly frictionless material
  • ½” wing nuts: 3
  • ½” washers: 5
  • ½” diameter bolt: 18” total
  • 2.5” wood screws: 28
  • 2” long ½” bolts: 2
  • ½” Lock nut: 1
  • ¼” wide bolts: 4
  • ¼” washers: 4
  • Small metal braces: 6
  • ½” screws: 4
  • ½” nuts: 2
  • Wood Glue
  • Gorilla Glue
  • Soldering Gun/Solder
  • Electronics kit
  • SilveRboard boards: 5


  • Don't do this project alone! Extra hands were essential to making this project a manageable one.
  • Measure twice(or three times) and cut once (or two times) to make sure things are right before wasting materials with bad cuts
  • Pre-drill holes for wood screws and other screws/bolts to prevent from splitting the wood
  • Attach the waveguide to the feed horn before gluing it to the connection box to allow more mobility and ease during construction
  • 5/8" bolts are sturdier for the center of the base and the rotational part of the plywood box, but you have to order 5/8" wing nuts online because they are rare, so using 1/2" objects is better if you plan to buy your supplies locally.
  • Read entire instructions before working on a section
  • To quickly find the center of rectangular pieces of wood, take a string, hold from corner to corner, and make a mark.

String center.png

Base Design[edit]

  • Cut wood 2x4’s into lengths (Quantities of cut pieces in parentheses):
    • 22” (4)
    • 25” (2)
    • 6” (1)
    • 3.5” (1)
  • Cut the plywood into rectangles:
    • 25”x25" (1)
    • 12”x12" (1)
Radio Telescope Base attached to stand.
The Telescope's base completed and attached to the stand. We used: *4 metal braces
    • 6”x14” (2)
  • Cut out the following pieces out of reflective insulation:
    • 12” square (1)
    • circle with a diameter of 17” (1)

(Note: the reflective insulation is used to create a smooth surface for the telescope to rotate. If you don't have access to this material, any smooth material will work.)

Put two of the 22” and two of the 25” 2x4’s into the shape of a square that is 25”x25” and attach them to each other using wood screws. Drill a ½” hole directly in the center of the 25” square of plywood. Place the 25” square of plywood on top of this frame and screw it down onto the square using wood screws in the corners.

Find the center of the 17” diameter circle and puncture a whole in the center that will be large enough for the rod to fit through it. Line up this whole with the drill hole in the center of the 25” square of plywood and attach the insulation to the plywood with wood glue. This is the base of the telescope.

Stand Design[edit]

Separate Parts for The Base

Drill a ½” hole into the center of the 12” square of plywood and into the center of the 6” 2x4. Place your two 22” 2x4s and the 6” 2x4 in the shape of a U, so that the 6” piece is in between the two 22” pieces and is flush with the ends of the 22” boards. Using wood screws, attach the 22” 2x4’s and the 6” 2x4. Drill one ½” wide hole into the tops of the 2x4's. These holes must be 1 3/4 inch down from the top of the 2X4's.

Now, center this U-shaped piece on the 12” square of plywood so that the drill holes match up on the 6” 2x4 and the plywood. Attach the U-shaped piece to the plywood using 2 wood screws driven through the 2x4 between the drill hole and the intersection with the 22” 2x4s. At the four corners of the U-shaped piece, attach metal brackets to the neck and the plywood to keep the structure from wobbling. Make sure that the screws you use are not too long or they will go completely through the plywood. Puncture a hole for the rod in the center of the 12” square of insulation and attach the insulation to the bottom of the plywood with wood glue, making sure that the holes on both pieces are lined up.

Connection Plywood Box Design[edit]

Cut out two 6”x14” plywood rectangles and two pieces of 14” 2x2’s. Drill a ½” hole in each of the 2x2s four inches from the end of the 2x2.

Lay one piece of plywood flat on the table and put the two 2x2s flush with the long sides of the plywood, one on each edge with their holes at the same end. Lay the other piece of plywood on top of the 2x2s so it looks like a sandwich. Attach the plywood to the 2x2s using wood screws at the corners of the rectangles.

Using a 12" section of bolt, attach the plywood box to the stand of the telescope on the U-shaped piece. Run the bolt through one side of the U-Shaped piece and then through the plywood box and then back through the other side of the stand. Secure the bolt on both sides with a washer and a 1/2" wing nut. When the wing nuts are tightened, the plywood box should stay in place. The waveguide will be attached to the top of the plywood box using gorilla glue.

Horn Design[edit]

Completed Feed Horn
Bessie's completed Feed Horn

Follow the same instructions as the original design which are as follows:

Cut out two of each of the dimensions to the right in the reflective Styrofoam board. Attach the pieces together so they make a large trapezoid with its respective piece (the one below it in the picture). Take these four large trapezoids and hold them together into the horn shape.

  • Use aluminum foil and aluminum tape to fill in any gaps between the sides
  • Make sure that the opening at the smaller end of the horn is 3”x6” so it fits comfortably with the waveguide later on
  • The wooden pieces attached to the outside are to keep the nut from digging into the Styrofoam

Mechanics Box Design[edit]

Follow the construction of the original HI Telescope design [[1]] '

Waveguide Box Design[edit]

Take the 3”x6”x14” waveguide box and cut off one end the end of the rectangular design. This allows the waveguide box to have a small rectangular opening at one side, which lets the waves to come through the opening of the box.

Next, you will need a ¼” drill bit and a power drill. From the end opposite of the rectangular hole in the front of the waveguide box, drill a ½” hole approximately 5.71cm from the back of the box (¼ of the wavelength) which makes a hole to put the probe into.

Probe Begin making the probe by cutting the wire to a length of 4.86cm. After cutting the wire to the correct length, you will solder the wire onto the N-connector. Once soldered, drill 1/8" into each corner of the N-connector. This will allow you to attach the probe to the waveguide by drilling 4 1/8" screws into each corner of the N-connector.

Attach the waveguide and the mechanics box the same way as in the original HI telescope design

To attach the waveguide to the connection box that is on the stand, use the gorilla glue and follow its instructions.

Declination Measurement Block[edit]

Cut a 3.5” piece of 2x4. Attach the protractor to the wood block as seen in the picture on the right using a ½” long screw.

Fashion a pointer for the protractor out of wire and attach it to the protractor in the middle of the bottom of the protractor. Make sure the screw is on enough that the wire does not fall off but that it does allow the wire to spin when the telescope is tilted.

After Mechanics Box and Waveguide are connected, use gorilla glue to attach the Declination Block to the waveguide in front of the mechanics box.

Protractor attached to wooden block to determine declination
Protractor attached to wooden block to determine declination

Attaching the Horn to the Waveguide[edit]

Place a 50” 2x2 inside of the connection box that holds the waveguide and center it under the horn so that the horn is as flat against the opening of the waveguide as possible and is resting on the side of the 2x2. Drill holes for bolts at two points: one 22.5” from the opening of the horn and the other 3” from the opening.

Put the bolts through the holes with the heads of the bolts being inside of the horn and the ends sticking out of the 2x2 and secure them with a washer and a nut.

Bend two of the braces at an angle so that they are flat against the inside of the horn and the outside of the waveguide. Drill a ¼” hole into the left and right side of the waveguide. Attach the braces to the waveguide with bolts that have the heads on the inside of the waveguide and secure with a washer and a nut.

Cut two 3”x6” pieces of plywood and drill ¼”l holes into them Puncture the horn so that the braces can be attached to hold the brace to the horn. Put a bolt through the hole in the horn and then through a 3x6 piece of plywood and secure with a washer and a bolt. This keeps the washer and nut from cutting through the side of the feedhorn.

Secure the feed horn additionally with duct tape, making sure to fill in any holes on the inside with reflective tape and the outside with regular duct tape.

Radio Telescope "Bessie" recording data
Radio Telescope "Bessie" recording data
Bessie standing upright
Bessie standing upright