Please note that the only in-app purchases available are tips. All functionality is included. Polar Scope Align will calculate the position of Polaris or. Octantis in your Polar Scope reticle for your location (using your phone's GPS or entering a location), 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 the website for details). It will even allow you to measure and correct a centering error of the reticle - very useful for polar scopes that are not easy to adjust (e.g. iOptron ZEQ25). In the settings you can also select from a collection of reticles, one that matches your own - currently iOptron, Astro-Physics, Takahashi, Orion, Skywatcher, Celestron, Meade, Vixen, Astrotrac, Losmandy, Kenko, Avalon Instruments, Tuthill, Telrad reticles are available. Feel free to contact the developer with any questions, feature requests, extra 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. Feature list: Accurate calculation of Polaris or Sigma Oct for any date and location, including effect of atmospheric refraction (and stellar aberration). Use device time/date and GPS location, or manually enter your own. Location manager with favorite locations, list of recent locations, online search and offline world database (cities/towns of at least 1000 population). Supports a multitude of polar scopes: iOptron, Astro-Physics RAPAS, 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, the Telrad, a couple for Astrotrac / Losmandy / Kenko / Avalon, the Tuthill Precision Polar Finder, the Meade 9x60 Polar Viewfinder and the Vixen Polaris and SX/SXD/SXP/AXD/GP/GP-DX/Polarie Polar Axis Scopes. Full app in red-color night mode - tools switchable to non night mode view. Moon phase & lunar Calendar with solar/lunar rise/set and twilight times. Wizard to calculate your reticle centering offset and correct or compensate for it. Zoomable reticle view. Alt-az alignment error display for mounts that calculate it after star alignment (e.g. iOptron iEQ45, CEM60). Polar alignment when your scope is not in zero position (for mounts like iOptron ZEQ/CEM on which you can always access the polar scope). Remember zero position on Celestron / Skywatcher / Orion etc reticles. Approximate daytime / no polarscope polar alignment tool. Great for solar imaging (including eclipses). Bubble level (using either gyro or accelerometer) and Compass heading, as well as magnetic declination reading. GPS accuracy & elevation data. Red/White/LED light. Dimming slider. Deep Space Object Database with 13000+ objects from several catalogs (Messier, Caldwell, NGC, IC, Herschell 400, Sharpless 2). the database is searchable and fully configurable with filters, various sorting methods etc.Over 20 calculators useful for observing and astrophotography, from eyepiece magnification and field of view, to imaging resolution and reducers. Xasteria: World astro-weather report based on 7Timer. data. Access to the latest water vapor satellite images. List of visible Iss passes and Iridium flares. iOptron, NexStar and Meade LX200 Star Lists. Support for iPhone & iPad from iOS 6. There is also a free ad-supported version that does not allow manual entry of date/time/location and lacks features like the zoomable reticle view, the bubble level etc, but does offer the base functionality.