Zmanim Clock Applet


This page uses a Java applet of a clock, to demonstrate the use of the Zmanim API. It shows a 24 hour clock for the current date with night shaded a darker color. Selected zmanim shown on the clock. For more information on the algorithms used see the JavaDocs. Additional information about the applet and it's history can be seen at the Zmanim Clock Applet Alpha Release post. The code can be downloaded on the KosherJava Downloads page

Location (1)
Latitude (2)
Longitude (3)
Elevation (4)
Time Zone (5) Algorithm (6)


1 This field will display as the location in the generated calendar. Manually entering a location will search for it (either by clicking the find button, or by changing to another field) and attempt to find it on a map. If found it will set the latitude, longitude and elevation of the first matching location found. Please ensure that the location on the map matches the location you are looking for. This look-up will not set the time zone. Please select the proper timezone.

2 Use the decimal format such as 40.096 for Lakewood, NJ. Use negative numbers south of the equator.
Note: For far northern (or southern) locations such as England some zmanim during part of the year such as early calculation of alos in the spring, that by calculation do not occur since the sun never reaches that far below the horizon (and actually calculate to an invalid mathematical value, see JavaDocs of AstronomicalCalendar for more information) will have a value of N/A. You can use the Map to select the latitude and longitude for your location. To use this feature, use the map controls to get to the desired location and click on it. This will set the longitude and latitude for the point on the map that you clicked. In addition, updating the latitude and longitude in the form will move the pin to the selected location.

3 Use the decimal format such as -74.222 for Lakewood, NJ. Use negative numbers west of the prime meridian (Greenwich). See the previous note for additional information.

4 Elevation in Meters above sea level. Negative numbers can not be used. This is used by sunrise and sunset calculations to adjust times based on elevation. Only sunrise and sunset calculations are adjusted as per Yisroel Vehazmanim and Calendrical Calcuations. When greater than 0, both sea level and elevation adjusted sunrise and sunset times will be exported. It is currently implemented by all algorithms in the Zmanim package using the formula zenith = zenith + Math.toDegrees(Math.acos(earthRadiusInMeters / (earthRadiusInMeters + elevationMeters))) found in Calendrical Calculations. A similar algorithm found in Maaglay Tzedek would be to add 0.0347 * squareRoot(elevationMeters) to the zenith. Use 0 to default to the standard algorithms.
Note: Elevation lookup courtesy of Google’s elevation API.

5 The Timezone. In most cases selecting the location on the map will properly set the timezone. If this does not work, please manually select the timezone for the selected location. Locations such as Israel where the start and end of daylight savings time varies from year to year will have an inaccurate start of daylight savings time. I will hopefully soon change the page to allow entry of optional start and end of daylight savings time.

6 Different algorithms are available for the sunrise / sunset calculations that form the basis for all zmanim calculations. USNO is the US Naval Observatory algorthm. NOAA is the National Oceanic and Atmospheric Administration algorithm. This is currently a palceholder.