Weather rules for closing the Blanco 4-m

If the visiting astronomer questions these rules, he or she should be referred to the Telescope Scientist (Tim Abbott) or Director (Steve Heathcote).

The Blanco 4-m lateral sliding doors must be closed when:

    Wind velocity has been greater than 25 mph on average over the last 20 minutes (to reduce dust deposition). Also, under these conditions, please try to observe downwind.

The Blanco 4-m dome MUST be closed when:

    Wind velocity has been greater than 45 mph on average over the last 20 minutes.
    (The telescope might still not shake badly but the air is dusty and will bring too much dirt inside the domes).

    Humidity is over 92 %, as indicated by the met tower and no other sensor

    Tmirror - Tdew < 2°C.

The Blanco 4-m may be opened when:   

Wind velocity less than 45mph on average over the last 20 minutes

    AND Relative Humidity is less than 85% for 30 consecutive minutes
    (in all cases, check outside that no water is dripping from the buildings).

    AND Tmirror - Tdew >= 2°C for 30 consecutive minutes