Emerald Observatory for iPad vs Acc.elerometer
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Emerald Observatory for iPad
This app provides a comprehensive astronomical display on a single screen, offering detailed information about celestial bodies and timekeeping. It features a heliocentric orrery, rise and set times, twilight information, and moon phase details. Users can navigate through time and set alarms for astronomical events.
- Astronomical information display
- Heliocentric orrery
- Rise and set times for Sun, Moon, planets
- Twilight times
- Moon phase and orientation
- World map of day/night regions
- Eclipse simulator
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Emerald Observatory displays a wealth of astronomical information all on one screen, in a unique but understandable format. Information includes: - 12- and 24-hour ordinary clock time - Times of rise and set for the Sun, the Moon, and the 5 classical planets - Times of the beginning and ending of twilight - Heliocentric orrery (display of the planets in orbit around the Sun) - Altitude and azimuth for the same bodies (one body at a time) - Current phase and apparent orientation and relative size of the moon - Current regions of day and night on a world map - The Equation of Time, solar time, UTC time, and sidereal time - Month, day, year, and leap-year indicator - Daily alarm (delivered as local notification on iOS 4+ if app is not running) - Eclipse simulator - Displayed times are synchronized via NTP to "atomic clock" standard - Uses iPad location, or the latitude and longitude may be set manually A setting is available to allow the display to stay on continuously. Tap on the display to move forward by a month, day, year, hour, or minute. A detailed manual for the operation of Emerald Observatory can be found at the "Emerald Sequoia LLC Web Site" listed below, at http://emeraldsequoia.com/eo/ If you are having any trouble with the application whatsoever, please see our FAQ on the support page listed below and then contact us through that page if your problem is not resolved. We take pride in responding promptly to all support email requests but we can't fix it if you don't report it (and we have no way to respond to Customer Reviews on iTunes). (NTP requires Internet access. Like all apps Emerald Observatory can not change the device's internal clock.)
Acc.elerometer
Visualize and record device motion with live sensor readings. Analyze acceleration, rotation, magnetic field, and attitude. Export data as CSV for further analysis.
- Live sensor readings
- Record experiments
- Analyze results on iPhone/iPad
- Capture motion on Apple Watch
- Export data as CSV
- Six measurement types
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See how your device moves with Acc.elerometer. View live sensor readings, record an experiment and examine the results on your iPhone or iPad. Capture motion on Apple Watch and send recordings to your paired iPhone for charts and CSV export. EXPLORE SIX MEASUREMENTS - Acceleration, including gravity, in G - User acceleration, with gravity removed, in G - Rotation rate around three axes in rad/s - Magnetic field in microteslas - Device attitude: roll, pitch and yaw in radians - Gravity along each axis in G View individual axes and vector magnitude where supported. Follow changing values and review recorded measurements to explore movement, rotation and orientation. RECORD AND REVIEW Choose the measurements you want to capture, then start and stop a recording. On iPhone and iPad, set the measurement interval from 0.1 to 1 second. Open saved recordings to inspect charts, switch between individual axes and vector magnitude for supported measurements, and identify gaps in the data. EXPORT YOUR DATA Export each measurement from a recording as a CSV file with timestamps and axis values. Choose Unix time, spreadsheet serial dates or formatted date strings for your analysis workflow. CAPTURE MOTION ON APPLE WATCH View sensor readings and record selected measurements on your wrist. Send saved recordings to the paired iPhone and follow transfer progress. Add watch face complications to see saved sensor maxima or recording status, and open the app to start a recording from the recording widget. FOR EXPERIMENTS AND EVERYDAY CURIOSITY Explore device motion for a physics demonstration, a development project or your own experiments. Measurements and recordings are stored on your devices. No account is required. Available readings and actual sampling intervals depend on the device and its sensors. Apple Watch recording duration is subject to watchOS background runtime limits. Watch complications show saved values from the app, rather than a continuous live sensor feed.
Screenshots
Verdict
The clearest difference is monetization model: Acc.elerometer at free against Emerald Observatory for iPad's paid. Acc.elerometer also leads on device support (3 vs 1). Emerald Observatory for iPad's advantage is ratings volume (95 vs 1) and update cadence (every 5 months vs every 11 months). On price, rating, review sentiment and ads 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. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 4.9 for Emerald Observatory for iPad against 5.0 for Acc.elerometer. That said, the two scores are not equally well evidenced: Emerald Observatory for iPad has 95 ratings behind it against 1, so its average is the more settled of the two. Written reviews are what separate them: 99% of Emerald Observatory for iPad's written reviews are positive against 100% of Acc.elerometer's.
Emerald Observatory for iPad ships an update every 5 months, Acc.elerometer every 11 months. The most recent releases landed on October 24, 2026 and October 20, 2026 respectively.
| Parameter | Emerald Observatory for iPad | Acc.elerometer |
|---|---|---|
| Price | Free | Free |
| Rating | 4.9 (95 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 98.6% of reviews | 100.0% of reviews — better |
| Number of ratings | 95 — better | 1 |
| Update frequency | Every 5 months — better | Every 11 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPad | iPhone, iPad, Apple Watch — better |
| Requires iOS | 17.0 — better | 26.0 |
| Further details — not scored | ||
| Size | 16 MB | 18 MB |
| Age rating | 4+ | 4+ |
| Developer | Bjorn Freeman-Benson | Pantiukhin Andrei |
Customer experience
Emerald Observatory for iPad
Acc.elerometer
Bugs and requests
Emerald Observatory for iPad
Requested features
14 requests- Port to screen wallpaper
- Large wall clock version
- Apple TV version
- Support for Uranus, Neptune, and Pluto
- iPhone and Apple Watch versions
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- Alarm functionality
- Screen dimming for night use
- Numeric display of values
- Switch altitude/azimuth by touching planet
- Push notifications for specific events
- Custom chime sounds for events
- Round earth display to match moon display
- iPad version of Chronometer iPhone app
- Tutorial mode or on-screen help
Acc.elerometer
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Emerald Observatory for iPad
No in-app purchases
Acc.elerometer
No in-app purchases
Questions
Is Emerald Observatory for iPad free?
Is Acc.elerometer free?
Which has better reviews, Emerald Observatory for iPad or Acc.elerometer?
Do Emerald Observatory for iPad or Acc.elerometer have ads?
Which is updated more often, Emerald Observatory for iPad or Acc.elerometer?
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