Zmanim Project

The Zmanim (“times” referring to the calculations of time that govern the start and end time of Jewish prayers and holidays) project is a Java API for generating zmanim from within Java programs. The Java Zmanim API has been ported to .NET (Jewish Zmanim Framework) and Objective-C (KosherCocoa). If you are a non programmer, this means that the software created by the project is a building block of code to allow other programmers to easily include zmanim in their programs. The basis for most zmanim in this class are from the sefer Yisroel Vehazmanim by Rabbi Yisroel Dovid Harfenes. The code available under the LGPL license can now be downloaded from the KosherJava Zmanim code repository. Older stable releases can be downloaded from the download page.
Please note: due to atmospheric conditions (pressure, humidity and other conditions), calculating zmanim accurately is very complex. The calculation of zmanim is dependant on Atmospheric refraction (refraction of sunlight through the atmosphere), and zmanim can be off by up to 2 minutes based on atmospheric conditions. Inaccuracy is increased by elevation. It is not the intent of this API to provide any guarantee of accuracy. See Using a Digital Terrain Model to Calculate Visual Sunrise and Sunset Times for additional information on the subject.

How to Use the API

Information on how to use the API can be found on the How to Use the API page as well as by reading the JavaDocs

Zmanim Calendar Generator

A sample use of the API can be seen in the calendar generator. This uses the Zmanim API to generate an annual Zmanim calendar in an Excel spreadsheet. Since this is a demo of the API, the calendar is generated using All (about 102 currently) possible zmanim that the API can generate.

List of Zmanim Supported by the API

The API currently can generate about 122 different zmanim. Explanation of most of these can be seen by browsing the JavaDocs. You can link to the documentation of the specific zmanim from the links below.

23 thoughts on “Zmanim Project”

Shmuel Weisberg ‍‍May 2, 2008 - כ״ז ניסן תשס״ח at 7:07 AM

Shalom,

I am curious if you’re aware of or compared your calculations to those used in kaluach. (www.kaluach.org). Yisroel also publishes some APIs via his site.

I am not asking out of idle curiosity but have an interest in knowing whether there are differences. I am not sure what offsets he uses for refraction nor which sunrise sunset calculation he uses. I know that he currently uses 0 elevation.

Shabbat Shalom,
(Rabbi) Shmuel Weisberg

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KosherJava Post author‍‍May 2, 2008 - כ״ז ניסן תשס״ח at 11:24 AM

Rabbi Weisberg,
I just took a look at the Kaluach JavaScript code (the Windows API is in a DLL/COM object without the sourcecode available to me). From the Javascript source it is clear that the code is based on the USNO algorithm. The offset to the 90° below the zenith used by their code for sunrise/set uses a combined 50′ (minutes of a degree = 50/60 or .83333) for refraction and solar radius. This is pretty much the standard used, where the solar radius is 16′ and the refraction average is 34′. They use the following offsets for zmanim.

Alos: 106°
Misheyakir: 101°
Tzais: 96°

Please let me know if you have any additional questions, though you are probably better off asking them.

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Jack Cohen ‍‍October 1, 2008 - ב׳ תשרי תשס״ט at 11:35 PM

Our shul is interested in featuring a display which among other things displays the countdown to the end of certain zmanim, such as
Countdown latest lime for:
Shema, Amida, Birkat Halevana, etc.

Since our shul has a great many late minyanim in the morning and continuous minyanim for Minha/Arvit, there is a great need for the people to know when these times occur.

We anticipate using LCD screens connected to a PC which will run the countdown clock among other messages (reminders for yaaleh v’yavo, hamelech hakadosh, etc.
Would you know anyone who would be able to help us with the programming of such an app?

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1. Moshe ‍‍April 16, 2011 - י״ב ניסן תשע״א at 11:10 PM
  
  Hey Jack, I don’t know if you have anything yet, but feel free to contact me. I may know of something.
  
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  1. Jerry Eizen ‍‍November 10, 2011 - י״ג חשון תשע״ב at 10:51 PM
    
    Moshe,
    
    Can you please contact me about the same item?
    
    We would like to get a Luach that has the Zmanim and “Davening Info” on it.
    
    Thanks….
    Jerry
    ffjerry AT gmail . c o m
    
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Bahaltener ‍‍December 2, 2009 - ט״ו כסלו תש״ע at 3:18 PM

Were there any efforts to port KosherJava API to C++?

Thanks.

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1. KosherJava Post author‍‍December 2, 2009 - ט״ו כסלו תש״ע at 4:36 PM
  
  Bahaltener,
  while porting should not be complex, I am unaware of effort to port it to C++ at the moment. The only complex part would be the portions of the code that use the Java Timezone and GergorianCalendar classes.
  
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  1. Bahaltener ‍‍December 2, 2009 - ט״ו כסלו תש״ע at 6:36 PM
    
    It would be interesting to port it to C++. I’ll take a look at the code. boost date_time API: http://www.boost.org/doc/libs/1_41_0/doc/html/date_time.html provides a useful set of calendar operations. May be it can be utilized to cover what KosherJava is using from Timezone and GregorianCalendar classes.
    
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KosherJava Post author‍‍December 3, 2009 - ט״ז כסלו תש״ע at 2:05 AM

You may want to touch base with Moshe Wagner who used the Java Zmanim API in the Qt C++ based Luach. I posted details in the ZmanimCLI (Command Line Interface) post. Though he did not do a direct port, he would likely be interested. I would be happy to host any port.

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1. Bahaltener ‍‍December 3, 2009 - ט״ז כסלו תש״ע at 1:15 PM
  
  On a side note. Why did you use GPL specifically for your API? Since it is a library, would it be better to release it under LGPL or other more permissive license?
  
  For example, let’s say there is a port of KosherJava to other language. I assume, since the original is under GPL (2 or higher) the port will be also under GPL2(+). GPL library can only be used in GPL (or compatible) licensed code I believe. Therefore not only closed source projects, but even open source ones which use GPL incompatible licenses (let’s say MPL, CDDL, EPL, etc.) will not be able to be linked with the library. (That’s why in general, libraries are released under more permissive licenses, like LGPL, FreeBSD, X11 etc.).
  
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2. Bahaltener ‍‍December 7, 2009 - כ׳ כסלו תש״ע at 1:06 PM
  
  Any thoughts on licensing?
  
  Reply ↓
  1. KosherJava Post author‍‍December 7, 2009 - כ׳ כסלו תש״ע at 3:12 PM
    
    Sorry for the delay in responding. There are two reasons that the code was released under the GPL and not the LGPL. The first one is that the oldest calculation engine used by the API, the ZmanimCalculator class, my modification of Ken Bloom’s code was released by him under the GPL. At this point, since I have another class, the SunTimesCalculator that returns the identical output and is not restricted to the GPL, this is no longer an issue, as long as this class is not included. The second one is that ideally, I would like people to release the entire app source, and thus the GPL, but I have as the code owner made some exceptions and in a few cases released the API to some developers under a non-transferable LGPL license. I would certainly allow the release of the C++ port to be released under the LGPL, and will consider a license change to the LGPL for the Java API in the future.
    
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    1. Bahaltener ‍‍December 8, 2009 - כ״א כסלו תש״ע at 12:17 PM
      
      A sheynem dank!
      
      I’ll start porting KosherJava API to C++ sometime soon I hope.
      
      Reply ↓
      1. KosherJava Post author‍‍March 13, 2010 - כ״ז אדר תש״ע at 11:58 PM
        
        Any updates?
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shaul ‍‍November 7, 2011 - י׳ חשון תשע״ב at 6:05 AM

Montreal canada why its says dawn 00:46? And all the zmanim are too early?

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1. KosherJava Post author‍‍November 7, 2011 - י׳ חשון תשע״ב at 7:07 AM
  
  Shaul,
  Thanks for contacting me. Are you using the API to generate these zmanim? Have a look at the Zmanim Map for Montreal where you will see accurate zmanim. If you are using the API, please share your code with me via the contact page so that I can try to help you debug it.
  
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Raphi ‍‍March 22, 2012 - כ״ח אדר תשע״ב at 6:51 PM

Hi, i’m traveling from Ben Gurion to Toronto on Motzei Shabbos/Sunday morning, as I can’t find an in-flight zmanim calculator. Can anyone help me with this?

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KosherJava Post author‍‍March 22, 2012 - כ״ח אדר תשע״ב at 8:15 PM

Raphi,
Have a look at the Chai Tables. Click on the “Online Tables…” link. The front page of this site links to the Chai Tables.
Htzlacha.

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Bernard Seeff ‍‍November 21, 2012 - ז׳ כסלו תשע״ג at 9:50 AM

The Zmanim calendar that is available for download is very useful, but I would like to request some modifications:
1. Please show the Hebrew date and Chaggim in English characters
2. Please include fast days as a “Chag”. There are some complications that a fast cannot start on a Saturday night, so it would be helpful if the system made this calculation as part of its output.

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1. KosherJava Post author‍‍November 21, 2012 - ז׳ כסלו תשע״ג at 6:11 PM
  Bernard,
  As far as the Zmanim Calendar,
  1. Maybe at some future date. Among other things, there are multiple way to transliterate them, and no one would be happy. See the documentation on the HebrewDateFormatter class to see some of the formatting options. The calendar code is in beta and likely to change dramatically, though I do not know when I will have time to do this.
  2. This is now done. I also added commas when multiple events happen in one day, so it now displays as “ויקרא, ראש חודש ניסן” and not “ויקרא ראש חודש ניסן”
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