# Observer Pro vs Mohr's CSA

The clearest difference is price: Mohr's CSA at $2.99 against Observer Pro's $13.99. Mohr's CSA also leads on review sentiment (100% vs 79%) and update cadence (every 3 months vs every 6 months). Observer Pro's advantage is iOS requirement (16.4 vs 26.5). On ads, in-app purchases, monetization model and device support there is nothing between them.

Observer Pro costs $13.99 and Mohr's CSA $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Observer Pro ships an update every 6 months, Mohr's CSA every 3 months. The most recent releases landed on September 21, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | Observer Pro | Mohr's CSA |
| --- | --- | --- |
| Price | $13.99 | **$2.99** |
| Rating | **[4.6 (49 ratings)](https://appshunter.io/ios/app/observer-pro/id462392803/reviews)** | — |
| Number of ratings | **49** | — |
| Positive reviews | 79.2% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 3 months** |
| Monetization | Paid | Paid |
| Size | 241 MB | 13 MB |
| Requires iOS | **16.4** | 26.5 |
| Devices | iPhone | **iPhone, iPad** |
| Age rating | 4+ | 4+ |
| Developer | [Joshua Bury](https://appshunter.io/developer/462392806) | [DRH YAZILIM VE MUHENDISLIK HIZMETLERI LTD STI](https://appshunter.io/developer/914295588) |

## What reviewers say

### Observer Pro

[App page](https://appshunter.io/ios/app/observer-pro/id462392803)

This app helps advanced astronomers and astrophotographers plan their observing sessions. It predicts object visibility, factoring in local obstructions, and provides weather forecasts. Manage observing lists and favorite sites to maximize your stargazing time.

**Highlights:** 14,000+ deep sky objects with photos, Local horizon profile measurement, Object visibility prediction charts, Featured object recommendations, Favorite observing site management, Astronomical weather forecasts

**Features:** Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 🎯 Excellent target planning and visibility forecasting
- 🌍 Custom horizon mapping feature is intuitive and unique
- 📊 Comprehensive visualization graphs and charts
- 🔍 Extensive DSO catalog with detailed object information
- 📸 Offline object images included

**What reviewers complain about**

- 🐛 Crashes when selecting catalog groupings (recent)
- 🐛 Keyboard doesn't dismiss after input (iPad issue)
- 🐛 Data loss - observer lists disappearing
- 🐛 Search function missing in recent version
- ⏱️ Lack of developer updates for extended periods

**Reported bugs**

- App crashes when selecting catalog groupings (Galaxy, Planetary Nebulae, etc.)
- iOS keyboard doesn't dismiss on iPad after clicking Done
- Observer lists and custom data disappearing after app closure
- Search feature missing in version 1.4
- Continuous crashes since recent updates

**Requested features**

- iPad native app with landscape mode support
- Search functionality restoration/improvement
- Export observer lists to other apps (Sky Safari, etc.)
- Support for planets, comets, and asteroids
- Observing notes and session logging


### Mohr's CSA

[App page](https://appshunter.io/ios/app/mohrs-csa/id914295585)

This application provides an interactive tool for visualizing and analyzing stress states. It offers 2D and 3D stress analysis with detailed graphical representations and allows for direct stress transformations on Mohr's Circle. Users can also access a built-in formula sheet, export results to PDF, and save their input data.

**Highlights:** Interactive Mohr's Circle, 2D & 3D Stress Analysis, Stress Transformations, Built-in Formula Sheet, Export Results to PDF, Save & Restore Data

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Observer Pro free?

Observer Pro costs $13.99, with no in-app purchases.

### Is Mohr's CSA free?

Mohr's CSA costs $2.99, with no in-app purchases.

### Do Observer Pro or Mohr's CSA have ads?

Neither Observer Pro nor Mohr's CSA shows ads.

### Which is updated more often, Observer Pro or Mohr's CSA?

Observer Pro ships an update every 6 months, and Mohr's CSA every 3 months. Most recently, Observer Pro was updated on September 21, 2026 and Mohr's CSA on September 22, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*