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Prayer Time Calculation

This section contains settings to configure location, calculation method and adjustments.

Location

For maximum accuracy, we recommend you let Prayer Silencer calculate Longitude, Latitude and Elevation. To reduce power consumption, and to ensure faster calculation, Prayer Silencer will first use network location to determine your current location. If the network location is unavailable, Prayer Silencer will use GPS location.

Calculation

The following standard calculation methods can be selected:

  • *University of Islamic Sciences, Karachi (Fajr Angle: 18,  Isha Angle: 18). Used in Pakistan, India, Bangladesh, Afghanistan and parts of Europe.
  • Islamic Society of North America (Fajr Angle: 15, Isha Angle: 15). Used in Canada, Parts of UK, parts of United States.
  • Muslim World League (Fajr Angle: 18, Isha Angle: 17). Used in parts of Europe, Far East, parts of United States.
  • Umm-Al-Qurra (Fajr Angle: 19, Isha interval 90 minutes from Maghrib during normal times and 120 minutes from Maghrib during Ramadan). Used in Saudi Arabia.
  • Egyptian General Authority Of Survey (Fajr Angle: 20, Isha Angle: 18). Used in Indonesia, Iraq, Jordan, Lebanon, Malaysia, Singapore, Syria, parts of Africa and parts of United States.
  • Fixed Ishaa Angle Interval (Fajr Angle: 19.5, Isha interval 90 minutes from Maghrib). Used in Bahrain, Oman, Qatar, United Arab Emirates.

The Juristic Method determines the Asr calculation.  The standard is used by Shafi. Hanbali and Maliki and Hanafi is used by Hanafi mathab.

* If you are unsure which method is best for you, we recommend the ‘University of Islamic Sciences, Karachi’ method, regardless of where you are in the world. Astronomical twilight and dusk begin at -18/+18 degrees below horizon respectively, irrespective of where you are located in the world. Read more on twilight at http://en.wikipedia.org/wiki/Twilight and http://en.wikipedia.org/wiki/Dawn . You can look at the pictures on the right of that article to see that we are concerned with Astronomical twilight/dawn. As for why it does not matter where you are in the world, please read the following:

“The distance of the Sun below the horizontal plane (we’ll assume that we are somewhere flat for the time being and call this the horizon to make things easier) is what determines how dark the sky will be, not  where you are on the Earth. You can measure a distance 18 degrees below the horizon plane from wherever you happen to be on the Earth, and once the Sun gets to 18 degrees below the horizon, the sky will be exactly as dark no matter where you are on the Earth. The point here is this: no matter where you are on the Earth, when the Sun is 18 degrees below the horizon, the sky will be “dark” in astronomical terms (at this point the illumination due to scattered light from the Sun is less than that from starlight and other natural light sources in the sky), and this is independent of your location on the Earth. Imagine you are at the South pole and it is Summer. The Sun will not dip below the horizon at all for several months because of your location on the Earth. This means that there will not be an astronomical twilight (or any other kind of twilight) for several months. Similarly, if you are at the South pole in Winter, you will not see the Sun at all for several months so you would be in astronomical twilight continuously for several months (the Sun would be about 23 degrees below the horizon in the very middle of Winter at the South pole). So your location determines how long the darkness will last, but if the Sun is 18 degrees below the horizon it will still be just as “dark” as anywhere else on Earth when the Sun is 18 degrees below the horizon.

If it helps, imagine that the Sun was 18 degrees *above* the horizon instead (and there were no mountains, buildings etc to block it’s light). No matter where you are on the Earth, if the Sun is 18 degrees *above* the horizon the day will look as bright as anywhere else, as long as the Sun is at 18 degrees above the horizon there as well.

Now, the question about if you were standing on top of Mt Everest and how that would affect things. The definition of twlight does not talk about the horizon, because this can change (e.g. if you were on Everest), but about the horizontal plane, or more specifically the “ideal horizon”. What this would mean if you were on Everest is this. If we consider the Sun 18 degrees below horizontal plane from Everest, this would mean that the Sun would not be 18 degrees below the horizon, although it would still be *very* close to 18 degrees below the horizon. No matter how tall a mountain you are on, the Earth’s diameter does not appear to change a great deal to if you were at sea-level because the Earth’s diameter is SO much larger than the height of the mountain. So the amount of sunlight that you will see in the sky from Everest at 18 degree twilight and from sea-level at 18 degree twilight will differ, but only by a very small amount. The problem with astronomical observations made once the Sun has gone below the horizon is from scattered light (light scattered by the gasses in Earth’s atmosphere). What matters here is the size of the Earth which is blocking the sunlight from the sky and as I just mentioned, this will only change by a small fraction no matter what mountain you are standing on.”

– Source: (Private email on 09/01/2008 – from Richard Lane, PhD Candidate, Institute of Astronomy, School of Physics, A29, University of Sydney, Australia)

Adjustments

If the prayer times calculated by Prayer Silencer are different from your local mosque/time table then you can set adjustments to produce the same prayer times.


Phone Silencing

This section contains settings to configure how and when the phone should be silenced.

Silence Profile

Defines whether phone should be set to completely silent or vibration mode.

Notifications

Show a notification in Notification bar each time Prayer Silencer makes the phone silent and normal.

Prayer Silencing

The following settings determine when the phone should be made silent:

  • Calculation type: For Dhur, Jumah and Isha fixed time type can be specified. When this option is enabled the phone will be silenced for the selected prayer same time all year around. This option is useful when your mosque has fixed Dhur, Jumah and/or Isha time. Isha time is likely to vary during summer and winter, please check your mosque’s timetable.
  • Start Time: How long after prayer start time should the phone be silenced.
  • Duration: How long should the phone be silenced for.
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