Emerald Observatory for iPad vs LSTclock
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.)
LSTclock
This utility app displays local sidereal time for registered locations on iOS, iPadOS, and watchOS. It can also calculate sidereal time and Julian Date for any date and time, and sync locations between devices.
- Local sidereal time display
- Julian Date calculation
- Supports multiple registered locations
- Location sync between iPhone and Apple Watch
- Date and time specific calculations
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LSTclock is an iOS/iPadOS/watchOS app that displays the local sidereal time (LST) at registered location(s). On iOS/iPadOS, it can also calculate LST and Julian Date for any date and time. The list of locations can be synced between iPhone and paired Apple Watch(es).
Screenshots
Verdict
The clearest difference is review sentiment: Emerald Observatory for iPad at 99% against LSTclock's 55%. Emerald Observatory for iPad also leads on rating (4.9 vs 3.8) and ratings volume (84 vs 10). LSTclock's advantage is monetization model (free vs paid) and update cadence (every 2 months vs every 5 months). On price, ads, in-app purchases and iOS requirement 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.
Emerald Observatory for iPad holds the better App Store score, 4.9 against 3.8. That said, the two scores are not equally well evidenced: Emerald Observatory for iPad has 84 ratings behind it against 10, so its average is the more settled of the two. Written reviews point the same way: 99% of Emerald Observatory for iPad's written reviews are positive against 55% of LSTclock's.
Emerald Observatory for iPad ships an update every 5 months, LSTclock every 2 months. The most recent releases landed on September 25, 2026 and September 9, 2026 respectively.
| Parameter | Emerald Observatory for iPad | LSTclock |
|---|---|---|
| Price | Free | Free |
| Rating | 4.9 (84 ratings) — better | 3.8 (10 ratings) |
| Positive reviews | 98.6% of reviews — better | 54.5% of reviews |
| Number of ratings | 84 — better | 10 |
| Update frequency | Every 5 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPad | iPhone, iPad, Apple Watch — better |
| Requires iOS | 17.0 | 17.0 |
| Further details — not scored | ||
| Size | 16 MB | 15 MB |
| Age rating | 4+ | 4+ |
| Developer | Bjorn Freeman-Benson | Tsuyoshi Sawada |
Customer experience
Emerald Observatory for iPad
LSTclock
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
LSTclock
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Emerald Observatory for iPad
No in-app purchases
LSTclock
No in-app purchases
Questions
Is Emerald Observatory for iPad free?
Is LSTclock free?
Which has better reviews, Emerald Observatory for iPad or LSTclock?
Do Emerald Observatory for iPad or LSTclock have ads?
Which is updated more often, Emerald Observatory for iPad or LSTclock?
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