The equipment on the ING Seeing Tower needs to be protected from bad weather and the remote-controlled Dome is the first line of defence. The Dome itself is vulnerable to ice and snow, and also to high winds, particularly when open. There are Orderly Shutdown Procedures for the seeing monitor equipment in case of lightning or snow storms (updated December 2007). This page is to outline conditions under which the ING Seeing equipment can be safely operated and recommend safe procedures for the protection of both equipment and personnel.

Protecting Equipment

• Maximum wind speed or gust speed: 50 kph (on the JKT anemometer). Above this speed, the Dome is vulnerable to damage and the effects of telescope shake are noticeable. The dome can be used at half-open position if wind shake effects become noticeable at lower speeds, since this depends on the wind direction. Note the WHT anemometer is sheltered from certain wind directions and is not a reliable indicator of high winds.
• Maximum relative humidity: 80% (on the seeing tower hygrometer). The tower PLC is programmed to close automatically above 90% RH, but the high voltage (400V) in the MASS photomultiplier diodes should be switched off (HV Off) if this hygrometer measures above 80%.
• Minimum temperature: 0 deg Celsius. Below this temperature there is a risk that the dome mechanism freeze in the open position, causing damage to the motors when you try to close the dome.
• Lightning: when lightning strikes are detected at less than 100 km, the orderly shutdown procedure should be applied.
• Brightness: between nautical twilights , the High Voltage of the MASS instrument may be safely operated. During the daytime, the manual shutter should be closed because even without high voltage, the PMT detectors are vulnerable to the buildup of photoelectrons. For the same reason, the MASS instrument should not be pointed close to the moon. On the other hand, RoboDIMM can even be operated before sunset.

Protecting ING Personnel

• In icy conditions, particularly accompanied by high winds, extreme caution should be taken when visiting the Seeing Tower.
• The trap door should always be closed when working in the Seeing Tower.
• Care should be taken not to collide with RoboDIMM when entering the tower from the trap door.
• When working alone on the tower, tell the observer the number of the IP phone (605) on the tower, so that they can contact you in case of a problem. The IP phone in the control room can be contacted on 452 from the tower.
• Always carry a torch and take care not to snag on cables while moving around in the dark on the Seeing Tower.
• Be aware that the emergency stop buttons on the tower will disable the dome shell motors.