Appendix H

Closing due to weather and snow & ice removal.

The telescope should ALWAYS be shut down and the dome closed whenever there is any chance of precipitation entering the dome.

If the weather conditions deteriorate such that you are forced to stop observing due to clouds, fog, high humidity or high winds. The following procedure should be used.

General shut down procedures for adverse weather or Clouds.

  1. Consult the IR weather map on Netscape to determine if this is a passing front or the system will be here for a while.

  2. If the front looks like it will only be here for a short period AND there is no threat of precipitation, do the following:

    1. Halt the scheduler running on N2MASS / S2MASS by pressing the S key. See Appendix J, Figure AL.
    2. Press `ESC' on NI2MASS then `A' to abort the script.
    3. Execute the shut_down.sct script, but DO NOT close the dome and DO NOT turn off the camera electronics.
    Alternatively you can do the following:
    1. Halt the scheduler running on N2MASS / S2MASS by pressing the S key. See Appendix J, Figure AL.
    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. Wait.
  3. If the weather gets better and you want to restart, execute the star_up.sct script, but since the dome is already open you don't need to open it.
  4. Now go to auto mode (select 1 on NI2MASS), replan the scheduler and restart.

  5. If the front looks like it will only be here for a short period AND there is the threat of precipitation, do the following:

    1. Halt the scheduler running on N2MASS / S2MASS by pressing the S key. See Appendix J, Figure AL.
    2. Press `ESC' on NI2MASS then `A' to abort the script.
    3. Execute the shut_down.sct script, including closing the dome, but DO NOT turn off the camera electronics.
    Alternatively you can do the following:
    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.
    6. Wait.
  6. If the weather gets better and you want to restart, execute the star_up.sct script.
  7. Now go to auto mode (select 1 on NI2MASS), replan the scheduler and restart.

  8. If the front looks like it will be here for a long period and you think you are done observing for the night, do the following:

    1. Go to the Telescope Shut Down section.

      A Dark frame must be taken, even if no actual survey data was taken for the night.

High winds

The telescope MUST be shut down and the dome closed if sustained winds are in excess of 35 MPH or gusts are stronger than 45 MPH.

  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.
  6. If no more data can be taken for the night, proceed to the Telescope Shut Down section.

Lightning

Whenever there is the threat of lightning nearby CLOSE DOWN IMMEDIATELY, see Appendix I for further instructions on lightning procedures & safety.

  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.
  6. If no more data can be taken for the night, proceed to the Telescope Shut Down section.

Fog or High humidity

Whenever fog is present, the dome should always be closed. The humidity will be too hight for taking data.

If the humidity is high (ie, moisture forming on outside railing) the dome should be closed, primary mirror cover closed and the telescope stowed.

  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.
  6. If no more data can be taken for the night, proceed to the Telescope Shut Down section.

Snow and Snow & Ice Removal

The dome slit should NEVER be opened when there is the chance for snow to fall on the telescope mirror.

If the slit, flap, or dome do not want to move due to ice, DO NOT use the motors to try to break the ice.

During the winter months snow may accumulate on the dome.

If conditions for snow exist, the dome should be moved (via dome rotation controller) so that the slit will face South (Northern Hemisphere) or North (Southern Hemisphere) when the telescope is stowed for the night. This procedure should help to melt the snow and ice that may form on the slit.
If snow and/or ice still exist on the slit by the late afternoon, then you will manually need to remove it using a broom or shovel. It may be easier to move the dome to a position where it is easiest to reach.

If the dome does not want to move via the motor control, due to ice.

  1. Turn off the motor immediately.
  2. Loosen the tension spring on the motor and disengage the drive gear from the dome.
  3. Manually try to move the dome to break the ice.
  4. If this procedure does not seem to work, see if you can determine where the ice is and try to thaw it with the heat gun.
  5. If none of these procedures seem to work, Call UMASS (Eric Howard).

The roof of the control room may also require cleaning.
Care should be taken as to not slip when cleaning the roof.

A ladder may be used to gain access to the roof. Use a shovel to remove any excess snow from the roof.
A second person is strongly recomended to help steady the ladder when climbing on the roof and in case of a slip or fall.

After the snow/ice has been removed, slowly and carefully open the slit. The Mirror covers MUST be closed.
If any snow starts to fall in or the flap/slit are frozen, Stop the slit immediately, close the dome, and reclean the slit.

If the slit or flap is frozen due to ice.

  1. Stop the motor immediately.
  2. If the slit will not move or stops, check the outside track opposide the slit opening for ice and remove.
  3. If the flap is frozen, get another person and manually try to break the flap free. Be aware that the hydraulic cylinders will not allow the flap to manually open much.
  4. If none of these procedures seem to work, Call UMASS (Eric Howard).
Appendix H

Version 2.3 - October 4, 1998