LSTclock: sidereal time clock

Name: LSTclock: sidereal time clock
Rating: 3.8 (10 reviews)
Author: Tsuyoshi Sawada

Local sidereal time clock

Free · Designed for iPad

10 Ratings
Age Rating

4+
Years
Category

Utilities
Developer

Tsuyoshi Sawada
Language

EN
English
Size

22.6
MB

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).

Ratings & Reviews

3.8

out of 5

10 Ratings

Extreme minimalism
05/12/2023
Mockspiral
The app works but I can’t seem to get the Lock Screen widget to show the LST. It shows a time when selecting the widget as a preview, but not on the active Lock Screen widget itself. I’ve tried all the privacy/notification settings I could find, updated iOS and reinstalled. The app doesn’t show up in some lists where other app settings would appear.
Extreme minimalism
05/12/2023
Mockspiral

The app works but I can’t seem to get the Lock Screen widget to show the LST. It shows a time when selecting the widget as a preview, but not on the active Lock Screen widget itself. I’ve tried all the privacy/notification settings I could find, updated iOS and reinstalled. The app doesn’t show up in some lists where other app settings would appear.
Almost; but, not quite.
12/15/2024
Universe Observer
Astronomers often need to use standard and local sidereal time which is done in the app; but more importantly for record keeping, they also need Julian and Modified Julian Dates. The app does not show JD or MJD and really needs to do this to be useful and bumped from three to five stars. Having to go to settings for time (which is not self explanatory) in order to get the JD and MJD is a pain. Just display both under the LST.Hope the developer takes this under advisement.14 December 2024 UPDATE: Tsuyoshi Sawada quickly responded with a note through the Apple App store that he added an optional setting to switch on or off the JD/MJD in his LSTClock and I tested it this evening when making my observations. It is a perfect solution to a long term issue that I have struggled with in my work having to look things up and compute JD and MJD with online calculators. Tsuyoshi, your solution is perfect! Thank you for responding so quickly and as promised, your app is not rated ⭐️⭐️⭐️⭐️⭐️ and more. Thank you so very much!

Developer Response
Thank you for the suggestion, I added an option to show JD/MJD in version 8.3.
Almost; but, not quite.
12/15/2024
Universe Observer

Astronomers often need to use standard and local sidereal time which is done in the app; but more importantly for record keeping, they also need Julian and Modified Julian Dates. The app does not show JD or MJD and really needs to do this to be useful and bumped from three to five stars. Having to go to settings for time (which is not self explanatory) in order to get the JD and MJD is a pain. Just display both under the LST.Hope the developer takes this under advisement.14 December 2024 UPDATE: Tsuyoshi Sawada quickly responded with a note through the Apple App store that he added an optional setting to switch on or off the JD/MJD in his LSTClock and I tested it this evening when making my observations. It is a perfect solution to a long term issue that I have struggled with in my work having to look things up and compute JD and MJD with online calculators. Tsuyoshi, your solution is perfect! Thank you for responding so quickly and as promised, your app is not rated ⭐️⭐️⭐️⭐️⭐️ and more. Thank you so very much!
Developer Response 12/08/2024
Thank you for the suggestion, I added an option to show JD/MJD in version 8.3.
Exceptional and multifunctional
12/25/2025
RDLGSTX
There is much to discover about sidereal time with this app. Take the time to read the user guide to access multiple functions. One suggestion for the developer: a user setting to allow the app to override the lock screen timeout optionally for a constant on display setting. Thank you for bringing this very useful app to the iOS environment.

Developer Response
Thank you for the comment. In version 9.1, an option to prevent the device from auto-locking (sleeping) was added. I hope it helps.
Exceptional and multifunctional
12/25/2025
RDLGSTX

There is much to discover about sidereal time with this app. Take the time to read the user guide to access multiple functions. One suggestion for the developer: a user setting to allow the app to override the lock screen timeout optionally for a constant on display setting. Thank you for bringing this very useful app to the iOS environment.
Developer Response Feb 6
Thank you for the comment. In version 9.1, an option to prevent the device from auto-locking (sleeping) was added. I hope it helps.
Small bugs but unique in function
12/11/2022
PHILIHP BUSBY
There seems to be a bug in how the Watch app enumerates complications, and took a few restarts and resets before I could get everything just right, but this app is unique in that you can get sidereal time with just your longitude and display it on the watch face.
Small bugs but unique in function
12/11/2022
PHILIHP BUSBY

There seems to be a bug in how the Watch app enumerates complications, and took a few restarts and resets before I could get everything just right, but this app is unique in that you can get sidereal time with just your longitude and display it on the watch face.

- Dropped support for iOS/iPadOS 17 and watchOS 10 (sorry for the inconvenience). - Modified the layout of the Main screen to adapt to iPhone Duo (iOS/iPadOS). - Fixed some issues on iOS/iPadOS 27: the "Play/Pause" button behaved unexpectedly; "Share" from Maps app did not work. - UI tweaks. - New icon.

Version 10.0 Oct 22

Data Not Collected

The developer does not collect any data from this app.

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

Supported Features
- Dark Interface

Information

Seller: Tsuyoshi Sawada
Size: 22.6 MB
Category: Utilities
Compatibility: Requires iOS 18.0 or later.

iPhone
Requires iOS 18.0 or later.

iPad
Requires iPadOS 18.0 or later.

Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.

Apple Vision
Requires visionOS 2.0 or later.

Apple Watch
Requires watchOS 11.0 or later.
Languages: English
Age Rating: 4+

4+

Learn More

Privacy Policy

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LSTclock: sidereal time clock

Ratings & Reviews

Extreme minimalism

Almost; but, not quite.

Exceptional and multifunctional

Small bugs but unique in function

What’s New

App Privacy

Data Not Collected

Accessibility

Supported Features

Dark Interface

Information

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