User's Guide to the Lick 36" Refracting Telescope

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Introduction
Dome
Telescope
Control Desk
Limits
Observing Hits

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Weather Limits

The 36" has weather limits comparable to the other telescopes but since the telescope is from 1888 one should take extra care to keep the telescope dry. The 36" does not have a computer displayed weather system, only a humidigraph on the end of the telescope. This means the 36" users need to rely on the 3-m operator or 1-m Nickel telescope weather station to get weather updates. 36" observers should be aware of the following conditions which limit or prevent operations of the telescope. Note that these limits are only guidelines. The decision to allow the 36" observers to open or close the dome is entirely at the discretion of the 3-m telescope operator. Wind Limits Average (MPH) Persistent Gusts (MPH) Into Wind 25 30 Crosswind 35 40 Downwind 45 50 Exercise caution using windscreen as windspeeds approach limits. Humidity 94% or at the 3-m telescope operator's discretion based on blowing fog, condensation on dome and handrails, etc.. Airbourne Particles/Ash Enclosures must be closed if airborne particles (e.g. ash from forest fires) are deemed a threat to the optics. A particle counter resides inside the Shane enclosure and measures particles 0.3 microns in size and 0.5 microns in size. The particle counter responds to outside changes, even when the enclosure is closed. The following threshold values (adopted 2013-08-05) apply (even when the Shane enclosure is closed): 0.3 micron 0.5 micron Warning 12000 800 Closure 17000 1000 Particle counts must remain consistently below the closure thresholds for at least 30 minutes before (re-)opening enclosure can be considered. If in doubt, contact the Shane telescope operator (8-0652). Snow on Dome If snow has accumulated on the dome and not been shoveled, the telescope dome should be kept closed to prevent snow from falling or blowing onto the telescope. Contact the 3-m telescope operator or support astronomer if you are unsure of the state of snow on the dome. Lightning If distant lightning can be seen but no thunder heard, there is no immediate threat and observing may continue provided there is no danger of rain. If lightning is 10 miles away or less (about 50 seconds from lightning to thunderclap), there may be a danger of a strike. 3-m telescope operator can stop observations to shutdown critical electrical systems as his or her discretion. Wait at least 30 minutes after the last audible thunderclap before declaring the storm passed and resuming operations.

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