Polar Scope Align vs OnStep Controller
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Polar Scope Align
This app calculates the precise position of celestial poles in your telescope's polar scope reticle for accurate alignment. It supports a wide range of reticles and corrects for atmospheric refraction, offering precision even at lower latitudes. Features include night mode, moon phase, and astronomical databases.
- Polaris/Sigma Octantis position calculation
- Atmospheric refraction correction
- Reticle centering error correction
- Supports numerous reticle types
- Red-color night mode
- Moon phase and astronomical databases
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Polar Scope Align is a free, ad-supported polar alignment app for iPhone and iPad. It calculates the position of Polaris or σ Octantis in your polar scope reticle for your location, date and time, helping you get a quick and accurate polar alignment with an equatorial mount. POLAR SCOPE ALIGNMENT • Accurate Polaris and Sigma Octantis position for your date and location • Atmospheric refraction correction for better accuracy, especially at lower latitudes - readings may differ slightly from simpler apps that skip this correction, but will agree with precise sources (USNO, scientific software) • Automatic time and location • Manual location support • Reticle centering-error measurement and correction • Zero-position help for common Celestron / Sky-Watcher / Orion style reticles • Full red night-mode interface SUPPORTED RETICLES Polar Scope Align supports 35+ polar scope and finder reticle types, including: iOptron, Astro-Physics RAPAS & PASILL, Takahashi (EM-10/11/200/400/500, NJP, PM-1, P2-Z), Sky-Watcher / Orion (including EQ6/AZ-EQ and Star Adventurer), Celestron, Meade, EXOS2, Bresser, Vixen (Atlux/SX/SXD/SXP/AXD/GP/GP-DX, Polarie), Astrotrac, Losmandy, Kenko, Avalon, Konus, Telrad, Rigel QuikFinder, and several older polar finders (Tuthill, Explore Scientific, Meade 9x60, Vixen Polaris, Celestron 7x50, Carton Optical). OBSERVING TOOLS The free version also includes: • Moon phase • Messier, Caldwell and bright-star database • DSS image downloads for included database objects • Saved, editable and printable DSO lists • 8 astronomy calculators for observing and imaging • Sample Pro tools available from Settings, including aurora forecast • iOptron WiFi Connect - report mount status, set mount Time/Date/Location LOOKING FOR ALIGNMENT WITHOUT A POLAR SCOPE? Polar Scope Align Pro adds the advanced tools many users search for: • Daytime / No Polar Scope Alignment • Camera Azimuth Calibration using the Sun, Moon, planets or bright stars • Laser / Hop Align for night alignment when Polaris is blocked • Push To / manual GoTo for non-GoTo telescopes • Live sky maps for Daytime Alignment, Laser / Hop Align, Push To and Hop To • Full 22,000+ object DSO database • Xasteria astro weather, aurora, satellite passes and widgets • 30+ calculators • Bubble level, compass and iOptron WiFi mount control • Apple Watch companion app • No ads If you only need accurate polar-scope alignment, this free version is a capable tool. If you want alignment without a polar scope, observing planning, weather and field tools, Pro is the complete version.
OnStep Controller
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OnStep Controller Take full control of your OnStep telescope mount from your iPhone. OnStep Controller is a clean, dark-mode companion app for amateur astronomers — connecting over WiFi (OnStep or OnStepX) or Bluetooth Low Energy (OnStepX with the BLE plugin required) to give you everything you need from setup to the final star. Connect and Configure Connect to your mount over your local WiFi network or via Bluetooth Low Energy. Send your GPS coordinates and current time directly to the mount for accurate alignment, and verify that the mount's site data matches your device before you start observing. Interactive Sky Chart Browse a live star chart showing hundreds of named stars and Messier deep-sky objects projected for your exact location and time. Pan and zoom freely, then tap any object to see its details and issue a GoTo command. Horizon, overhead, and meridian flip limits are drawn directly on the chart so you always know what your mount can reach. Visual Star Alignment Begin a 1- to 9-star alignment from the Setup tab and get guided through the process on the sky chart. Pick your alignment stars visually, slew to each one, then fine-tune with the on-screen directional pad and accept. Full Mount Control Move the mount in any direction at four slew rates — Guide, Center, Find, and Slew. Toggle tracking on and off, switch between Sidereal, Lunar, and Solar tracking rates, park and unpark, and find home — all from a single screen with live RA, Dec, Alt, and Az readouts. GoTo from a Catalog Search a built-in catalog of stars, open clusters, globular clusters, nebulae, galaxies, and planetary nebulae. Filter to objects currently above the horizon and slew to any target with a single tap. Or enter coordinates manually for objects not in the catalog. Designed for the Dark The entire app runs in forced dark mode with a deep red accent color chosen to protect your night vision at the eyepiece. Requires an OnStep or OnStepX telescope mount controller. WiFi works with both; Bluetooth requires OnStepX with the BLE plugin installed. iOS does not support Classic Bluetooth.
Screenshots
Verdict
The clearest difference is in-app purchases: OnStep Controller at none against Polar Scope Align's 3. OnStep Controller also leads on ads (none vs shown). Polar Scope Align's advantage is iOS requirement (13.0 vs 17.0). On price and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Polar Scope Align sells 3 one-off in-app purchases. OnStep Controller asks for nothing beyond the download.
| Parameter | Polar Scope Align | OnStep Controller |
|---|---|---|
| Price | Free | Free |
| Rating | 4.7 (171 ratings) — better | — |
| Positive reviews | 91.3% of reviews | — |
| Number of ratings | 171 — better | — |
| Update frequency | Every 2 months | — |
| Ads | Yes | No — better |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 13.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 23 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | Dimitrios Kechagias | Gray Digital Arts LLC |
Bugs and requests
Polar Scope Align
Reported bugs
6 issues- Date and time dial do not match correctly
- GMT and LST times appear to be switched
- App crashes or fails to initialize for some users
- Alignment accuracy varies inconsistently between sessions
- Location detection issues with cell tower vs GPS
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- Reticle display not rendering properly in some cases
Requested features
7 requests- Online video tutorials demonstrating all features
- Remove or reduce center dot size in reticle
- Larger, bolder font options for better readability
- Brighter star options for southern hemisphere alignment
- Smaller ad button or ad customization
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- Better beginner onboarding and instructions
- More robust alternative alignment methods for southern hemisphere
OnStep Controller
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Polar Scope Align
- Tip 1x$0.99
- Tip 4x$3.99
- Tip 10x$9.99
OnStep Controller
No in-app purchases
Questions
Is Polar Scope Align free?
Is OnStep Controller free?
Do Polar Scope Align or OnStep Controller have ads?
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