Hi Larry,

I think I meant that considering nothing changes (like maybe in a permanent setup). More accurately, you will usually need to do the calibration wizard once per night. However, if you change equipment or camera orientation then you will need to calibrate again. If you do a pier flip, you don't necessarily need to calibrate, but you may have to invert the PEC curve.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro: http://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: http://www.gralak.com/apdriver
Author of PulseGuide: http://www.pulseguide.com
Author of Sigma: http://www.gralak.com/sigma