This app offer various time keeping services
o Calendar for any year of your choice with National Holidays, world wide
o Timedifference computer
o Astro clock / Celestial Body
o Analog clock for presenters

Calendar
Anytime Calendar computes an annual calendar for any year. It will also mark national holidays for all regions (countries) world wide. You select the year, Anytime Calendar display the calendar for that year. This is a Gregorian calendar which is the calendar most common in use. It is a solar calendar i.e. it drifts very little with respect to the actual solar year. A regular Gregorian year consists of 365 days and in a leap year, an intercalary or leap day is added as 29 February making the year 366 days. Normally a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years.

Time Difference
Create a list of events, date and time, and the compute the time difference between NOW and your list of events. T he time difference is displayed in: years, months, weeks and days plus hours and minutes. Useful for keeping track of contact lenses (how long since last time you changed), birthdays (compute how old someone is)

Presenter clock / Analog Clock
This has been designed out of necessity. When presenting generally in a meeting, the clock will display time viewable at a distance. It also offers start/stop modes making it is easy, at a distance, to see how long you have been presenting or how far into the meeting you are.

Astro clock
This has been designed out of necessity. I am a GA pilot flying VFR. Often I need to know sunset and dusk times at a specific location in order to remain within VFR rules. This is also useful when travelling to a new location in general. When is dusk or sunset? You will find a range of useful data points computed for you in this section
Sun: /Set/Civil twilight, Nautical twilight. In addition the celestial position of the sun is computed (at the current time). Useful if you want to avoid driving or landing directly into a setting (or rising) sun.
Moon: Rise/Set/and celestial position of the moon is computed as well as the moon phases.
You can add as many preset (lat/lon) locations as you like.

Dedicated apps
If you find the Presenter clock useful, but want this as separate app download from Play here:
Google Play Store
Name: PresenterAnalogClock
Direct link: Google Play Store
Screen
It has been tested on various screen formats including Pixel Fold.
This APP is designed with API features that require API35 (Android 15 or higher) or higher!

Note, the app disables screen timeout
APP Privileges
android.permission.WAKE_LOCK
- Keep screen on
android.permission.INTERNET
- Google analytics
Acknowledgements
JODA Time
http://www.joda.org/joda-time/
Great library for time/date computation.
Astronomy Engine for Kotlin
Available from GitHub by Cosinekitty. I have added to and improved it, to create this app.