Polar Scope Align

Polar Scope Align will calculate the position of Polaris or σ Octantis in your Polar Scope reticle for your location (using your phone's GPS or manually), allowing a quick and accurate polar alignment. It is one of the few programs that are accurate in lower latitudes by correcting for atmospheric refraction (so expect results to agree only with precise software and not most simplistic "polar align" apps - see the "Accuracy" section in help for details). It will even allow you to measure and correct a centering error of the reticle. In the settings you can select from a vast collection of reticles, one that matches your own. Pretty much every reticle in the market is supported:
iOptron old & new, Astro-Physics RAPAS & PASILL, various versions of Takahashi EM-10/11/200/400/500, NJP, PM-1, P2-Z, the latest Orion / Skywatcher, the Classic Skywatcher / Orion / Celestron / Meade / EXOS2 / Bresser, the Telrad, Rigel QuikFinder, a couple for Astrotrac / Losmandy / Kenko / Avalon, the Vixen Atlux/SX/SXD/SXP/AXD/GP/GP-DX/Polarie Polar Axis Scopes, a Konus and several Polar Finders: Tuthill, Explore Scientific 8x50, Meade 9x60, Vixen Polaris, Celestron 7x50, Carton Optical. PoleMaster help view for South Hemisphere users.
Feel free to contact the developer with any questions, feature/reticle requests and any problems you have with the app. If you like Polar Scope Align, please consider leaving a review on the app store.

Main features:

-Accurate calculation of Polaris or Sigma Oct for any date and location, including effect of atmospheric refraction (and annual aberration, nutation). Most other apps do not perform precision calculations, so please only compare app readings to accurate sources (USNO, scientific software etc).
-Automatic Time/Location.
-Calculation and correction/compensation for off-center reticles.
-Remember zero position on Celestron / Skywatcher / Orion etc reticles.
-Full app in red-color night mode.
-Moon phase.
-Messier, Caldwell and Bright star database.
-Download and explore DSS color images of the DSO database entries.
-8 calculators useful for observing and astrophotography.

This free version is ad-supported. You can also try the ad-free Pro version with many extra features:

-Ability to manually enter time/date and location (including saving favorites, list of recent locations, loading from world location database, searching online).
-Zoo