Cahill Rooftop Observatory

User Guide: 10-Inch Celestron

The 10-inch once stood atop the Downs roof. Remounted through the heroic efforts of Mike Roy, it's now available to rooftop observers who don't want the hassle of getting out the more elaborate 14-inch. The 10-inch can be used with any 1.25" eyepiece, filter, or Barlow lens. If you want to do astrophotography or wide-field observing, you should use the 8-inch or 14-inch instead.


Telescope Setup


  1. First, roll the C-14 out into the lobby to make room for the C-10. See the C-14 manual for details.
  2. Loosen the three support screws until they are almost completely up (at most a quarter of an inch showing below the buggy). Any lower, and they'll bang into the threshold when you roll the telescope outside. The front screw is particularly prone to snags, since it's far from any of the wheels.

    Get the C-14 clear

    Loosen screws...

    ... to this high

  3. Pull the telescope out onto the deck and turn it so that it's facing south. Make sure none of the three support screws are located over a crack in the tiles.
  4. Tighten the support screws until all three wheels can turn freely. The screws can be hard to turn, as each is carrying a third of the telescope's weight. Pushing up on the leg of the mount will take some of the weight off the screw and make things easier.

Setting Up the Tube

  1. Take the power supply out from under the telescope. Take the white cord with the black plug and plug it into the blue housing on the south side. The two prongs on the plug are different sizes – make sure you get the right polarity or it won't go in. Plug the gray cord into the outlet by the door (you will probably need an extension cord).
  2. Flip the switch on the power supply to the top position. You should see a light on both the power supply and the mount.
  3. Uncap the main scope, the finderscope, and eyepiece hole and put the caps where you won't trip over them.
  4. Remove a diagonal and whatever eyepieces and filters you wish to use for the observing run from the storeroom cabinet. Again, put them somewhere where you won't trip over them. The tray beneath the telescope makes an excellent spot.

    Black plug and light

    Power up

    Handy storage area

    Insert Diagonal

    Tighten Screw

  5. Slide the diagonal into the telescope back and tighten the long set screw.
  6. You're now ready to observe!

Telescope Use

Telescope Shutdown

  1. Remove the eyepiece from the diagonal, put any dust caps on, and return it to its box. Take the diagonal out and put it back in its box. Put all eyepieces and diagonals back in the cabinet in the storeroom.
  2. Unplug the telescope power supply from both the wall outlet and the mount. Coil the cables neatly and put the power supply and cables on the tray underneath the mount.
  3. Recap the main aperture, finderscope aperture, and eyepiece hole.
  4. Rotate the scope in RA to the storage position (finderscope on top, both fork arms at the same height) and lock the RA brake.
  5. Rotate the scope in dec to the storage position (pointing up, perpendicular to the fork arms) and lock the dec brake.

    Storage position

    Parking spot

  6. Loosen the three support screws. Remember that they need to be high enough to clear the entrance.
  7. Roll the telescope back into the storeroom, and turn it around so that it is facing the doorway. Park the telescope next to the table, as close to the wall as you can get without brushing against it.
  8. Tighten the support screws, holding up the mount if neccessary, until all three wheels can rotate freely. This helps keep the tires from deforming under the telescope's weight.
  9. Move the C-14 back into place. Check the C-14 manual, as it's much easier to get the telescope out than to get it back in!