Observing In Higher Humidity

A threat to all telescopes is possible condensation on its instruments and primary mirror during high humidity conditions. Using too conservative delta dew-point control limits for telescope closure can reduce valuable observing time. SALT recently changed its operational procedure in high humidity conditions to gain as much additional observing time as possible, without subjecting the telescope and its instruments, to the harmful effects of condensation. This paper will describe how the SALT Operations team managed to safely reduce the delta dew-point control limit and thereby gaining valuable observation time without investing significant amounts of money.