Apart from the most reliable app for polar alignment (with or without a polar scope), PS Align pro has become the astronomer's swiss-army knife with all the tools added over the years. Remember, all features & updates are free forever, the only in-app purchases are donations (tip jar).

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 the polar scope reticle that matches your own, from a vast collection:
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 PF-L/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. If you have one not included, just ask the developer to add it!

Feature list:

-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).
-Use device time/date/location, or enter your own, or pick from online & offline world databases via the Location Manager.
-Approximate daytime / no polarscope polar alignment tool. Great for visual use, solar imaging (inc. eclipses) and even limited short focal length astrophotography.
-Laser / Hop Align for nighttime alignment using a calibration star for obstructed or not visible polar star, or for improving laser align.
-Full app in red-color (or alternative green, white) night mode - tools switchable to daytime view.
-Deep Space Object (DSO) Database with 13000+ objects from several catalogs (Messier, Caldwell, NGC, IC, Herschell 400, Sharpless 2). Search, apply filters, sorting, download DSS color images for all items, or get help finding them with your non-goto telescope with the Push-To function.
-Over 30 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
-Water vapor satellite images.
-List of visible ISS and bright satellite passes.
-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 and customized routines & tools: 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.
-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.
-iOptron, NexStar and Meade LX200 Star Lists.
-Support for iPhone & iPad from iOS 9 (and iPod Touch, except tools that require the compass).

What’s New

Version 5.6

Why not help out by rating the new version! There are never popups to nag you (annoying!), which mean less reviews than other apps.
Big update with many new features:
- Added Vixen PF-L polar scope.
- New Laser / Hop Alignment tool. Increased accuracy over the daytime / no polar scope tool for night time alignment using a calibration star.
- Dynamic Type support for larger fonts. The app will follow your device settings (Settings→Display→Text Size).
- Push-To/Hop-To display improvements.
- Dimmer maximum increased and light tool color adjustment fixed for green/white modes.
- DSO DB search now also looks in constellation & stellar designation fields.
- Xasteria changes:
-- Separate 7Timer/Dark Sky configuration options for visualization mode, time header format, display width.
-- Added arrow icons added for wind direction, improved existing icons and colors.
-- 7Timer forecast length configurable up to 8 days max (seeing/transparency only for first 3 days), cloudcover layer breakdown option, precipitation amount, wind direction.
-- Configurable Dark Sky forecast step (1h-3h) and precipitation amount among new options in settings.
-- Moon altitude per time point.
-- Updated Light Pollution info page and corrected Green/White night mode colors.

Ratings and Reviews

5.0 out of 5
163 Ratings

163 Ratings

BigTenDad ,

Not Sure about Usefulness

I recently purchased the Pro version of this app. I use it with and Explore Scientific iEXOS-100 eq mount and a William Optics Z61 scope. I have an extremely limited view of the northern sky (none at all — trees and other obstructions). Therefore I need a way to polar align with no view of Polaris. I tried over and over again to “align” my mount. However, I use the compass to get a rough setting for North. Place my iPhone on the mount head and, as I do so, it drifts toward the West. When it finally settles, it wants me to make a correction by almost 15-18 degrees. This is way off. I take the iPhone off the mount, open the compass away from the mount and it again shows the correct North. There must be a way to compensate for this aberration. If there isn’t, the app is worthless for my use. By the way, I do love all the positive responses but, for me, it has not be useful so far.

Update: (3/7/19) Update: I’ve made some adjustments, including purchasing a five inch dovetail and an inexpensive smart phone mount. This gets my iPhone away from the core of the mount. I tried a few nights ago (3/3/19) and was able to do a decent polar alignment using just PS Align Pro. Now I am able to give the app five stars.

Developer Response ,

Hello, and sorry for the trouble you had. However, the review is rather unfair, as the in-app help is very clear about this: you can't just put the phone on the mount, the compass will be way off! That's how magnetometers work. There is an entire section about how to avoid this with various suggestions if you click the info button and read the help for the Daytime Alignment tool. In fact, there have been astronomy publications showing phones on mounts as a good idea and I point out how bad advice that is. I didn't think this would be missed, the header text points you to the info button to learn how to use the tool, perhaps I'll find a way to make it even more clear on the next version.

In any case, because you seem to have a nice setup for astrophotography, I should warn that the Daytime Alignment tool in any case is just a small utility that is meant mainly for aligning for solar tracking or at most visual observation in the night time. If you are planing to try some astrophotography, without access to the north I think you'd have to do the (more cumbersome unfortunately) process of drift alignment.

You can always use the contact form on the Polar Scope Align site to write to me directly with any concerns.

Annoyed consumer 6613 ,

Surprisingly Useful

I purchased the Pro version to give it a try and help me setup an Orion Atlas Pro mount. The app was surprisingly easy to use with great functionality. It can be as easy as opening it up to see what position to align your mount or dive into more detail about various objects in the sky and where they’re located. You can change the mount type being setup for a variety of brands that any backyard astronomer would be familiar with. Additionally, there’s an exceedingly huge catalog of information under the menu. Press the cog wheel and you open up the object list which was a delightful addition that justified supporting the app and purchasing the Pro version.


New to Tracking—Very Helpful!

I recently bought my first tracking mount, iOptron SkyGuider Pro, and found it much easier to find polar alignment with this app.

Same for solar alignment—a little difficult to find a way to mount the phone (which is not the app’s fault), but kept the sun in my camera’s viewfinder at 500mm for more than an hour. Probably could be better if I worked harder on it, but I was able to get an ISS transit. I wish I bought this before the 2017 eclipse!

App Privacy

The developer, Dimitrios Kechagias, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Usage Data

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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