Re: How often do you need to polar align a permanent mount?
In SE Arizona at 5000' elevation, where we can have a pretty good heat cycle from day to night, I check and adjust polar alignment if needed once a year. If there are any adjustments needed, they are small. But remember metal can sag, fatigue, heat cycle, bolts can loosen up, fasteners can back off and so on. I also go over all the fasteners on the OTA and make sure they are snug. Generally in September after monsoon is over and prior to starting the new season.
Mike J. Shade
Mike J. Shade Photography:
In War: Resolution
In Defeat: Defiance
In Victory: Magnanimity
In Peace: Goodwill
Sir Winston Churchill
Already, in the gathering dusk, a few of the stars are turning on their lights.
Vega, the brightest one, is now dropping towards the west. Can it be half
a year since I watched her April rising in the east? Low in the southwest
Antares blinks a sad farwell to fall...
Leslie Peltier, Starlight Nights
International Dark Sky Association: www.darksky.org
firstname.lastname@example.org [mailto:email@example.com] On Behalf Of CurtisC
Picking up from Mr. Erickson's post -- Palomar Mountain is bounded by major faults on both the northeastern and southwestern sides of the block, and it is, of course, pretty close to the San Andreas and San Jacinto Fault Zones. The foundation of the 200-inch has adjustments for polar alignment, but -- to my knowledge -- it has never been readjusted due to effects from an earthquake. Nobody currently on staff remembers any such realignment. The mm 7.2 Cucapah Earthquake in Baja Calif. in 2010 was strong enough to slosh water in the observatory's water tanks, but it didn't affect any of the telescopes.