Appendix I

Lightning procedures & safeguards

If lightning is in the area or there is the threat of lightning occurring the following procedures MUST be taken to insure the protection of the camera electronics.

If Lightning strikes are occuring nearby. Do the following immediately:

  1. Halt the scheduler.
  2. On the TCS computer press the ALT-S keys to stow the telescope.
  3. On the TCS computer move the highlight bar to the Motion menu and then move down to the Mirror Open option and press the ENTER key to remove the check mark. This will close the large mirror covers on the primary.
  4. On the TCS computer move the highlight bar to the Motion menu and then move to the Stow dome option and press ENTER to stow the dome.
  5. Close the dome. While dome is closing continue on with the following procedures.
  6. Turn off Camera electronics.
  7. Unplug all Green taped cables on the camera and camera electronics.
  8. Take cover. Do not go to the 60" if the strikes are very close. It is safer to stay inside the control room/dome than become a lightning rod outside.

General Lightning procedures for 2MASS operations.

Remember that if the camera or its electronics are damaged by lightning it will probably take a couple of months to get them back online.

The computers in the control room are on UPS and should not need to be disconnect. Use your own discression if lightning is in the area. Be sure that the items are shut down before disconnecting power.

If in doubt as to what to do, then follow the procedures for lightning is probable to be on the safe side.

  1. Halt the scheduler.
  2. On the TCS computer press the ALT-S keys to stow the telescope.
  3. On the TCS computer move the highlight bar to the Motion menu and then move down to the Mirror Open option and press the ENTER key to remove the check mark. This will close the large mirror covers on the primary.
  4. On the TCS computer move the highlight bar to the Motion menu and then move to the Stow dome option and press ENTER to stow the dome.
  5. Close the dome.

If the weather conditions look as if there is the Chance of lightning in the area during the daytime, perform the following procedures to provide a modest safeguard for the camera electronics.

On the camera and telescope there are 4 connectors that will need to be unplugged in the correct order to safeguard the camera from potential damage. Each connector is marked with a green flag (piece of tape) to show what needs to be unplugged.

  1. The dome camera electronics (box in dome and in control room) need to be turned OFF before proceding.
  2. On the dome camera electronics box, unplug the 115V supply from the front of the box.
  3. On the dome camera electronics box, there are two connectors that need to be unplugged.
  4. The camera heater cable (near where the LN2 fill connectors are) will need to be unplugged only when there is the immediate threat of lightning (If the camera heater is unplugged, the camera will need a couple of hours for the temperatures to settle down and the camera is usuable again). At this point the temperature readings may start to move slightly and the heater readings will be wrong.

This procedure should safeguard the camera electronics from being damaged if lightning should strike nearby.

If lightning is probable or seen in the area, perform the following procedures to provide a best safeguard for the camera electronics.

On the camera and telescope there are 4 connectors that will need to be unplugged in the correct order to safeguard the camera from potential damage. Each connector is marked with a green flag (piece of tape) to show what needs to be unplugged.

  1. The dome camera electronics (box in dome and in control room) needs to be turned OFF before proceding.
  2. On the dome camera electronics box, unplug the 115V supply from the front of the box.
  3. On the dome camera electronics box, there are two connectors that need to be unplugged.
  4. The camera heater cable (near where the LN2 fill connectors are) will need to be unplugged only when there is the immediate threat of lightning (If the camera heater is unplugged, the camera will need a couple of hours for the temperatures to settle down and the camera is usuable again). At this point the temperature readings may start to move slightly and the heater readings will be wrong.

This step will completely isolate the electronics located inside of the camera from the outside world and should provide the highest level of protection from damage.

Reconnecting the camera & electronics cables.

Be very careful when plugging in the connectors and always check that no pins on the connector are bent before plugging them in.

  1. Re-connect the heater connector, if disconnected
  2. Re-connect the 2 green taped connectors to the dome camera electronics box.
  3. Re-connect the green taped power cable to the camera electronics box on the dome floor.

If the camera heaters were disconnected it will take about 1-3 hrs for the temperatures to stabilize, depending on the time that they have been offline. The camera should not be used until all camera array temperatures have settled back to -192C.

Appendix I

Version 2.3 - October 4, 1998