Islamic Astronomy Software : Digital Falak

Android is a linux-based operating system for mobile phones such as smartphones and tablet PC. Android provides an opensouce platform for developers to create their own applications for use by a variety of mobile devices.

Android already has some changes starting from android version 1.1 to the current android version 7.0. Of course with the development and improvement of android, the users were involved to develop various applications, both for personal and public purposes.

Android development is also up in the field of Islamic Astronomy. The "Digital Falak" app is one of the applications of Islamic Astronomy based on android, created by Ahmad Tholhah Ma'ruf published in the Playstore. The application is made in 2012 but in 2014 this new application is released. And in the middle of 2015 this app is officially uploaded in Playstore and can be used by many people especially for android users. Download this app in Playstore or in Digital Falak Web
.

Digital Falak Icon

Digital Falak contains several programs, there is Prayer Time, Qibla Compass, Hijri Calendar, Location Data, and Istiwak Time.

Local Prayer Time and Masehi Calendar

• Prayer Time.
Prayer Time in this application displays some data that is: the time of salat Zuhr, Asar, Magrib, Isha, Imsak, Dawn (Fajr), Thulu, and Duha. Available in 2 time, local time and istiwak time. We can also adjust the criteria and ihtiyath time in the setting menu. The prayer time in this application also has the alarm for remember us to do pray.

Istiwa Prayer Time and Hijri Calendar

• Hijri Calendar
The Hijri calendar in Digital Falak uses the two-book method of making it by using "Fathu al-Rouf al-Manan" and "Nurul anwar". Users just choose which books to use in the settings menu. there is also Masehi/public Calendar

Qibla Compass and Rashdul Qibla Calculation

• The Qiblah Compass
The Qiblah compass is quite easy to understand especially for who do not know the calculation of the Islamic Astronomy, because in it already has a Qibla Compass program, the direction shown by the compass will face the qibla, but this application has a weakness, because the base of the compass using magnetic sensor, then this application is very influential with the magnetic force that surrounds the user.
The Qibla Compass feature also requires magnetic sensors, so for mobile devices that do not have magnetic sensors can not use this feature. Instead there is also a feature Rashdul Qibla calculation, the calculation of the time where the shadow of the Sun will face the qibla.

Location Data Menu

• Location data
Location data in digital falak can be used to find the latitude, longitude, height of place, time zone and place name according to the position in GPS. This data is always updated and can also update by using the internet after the phone is connected to the internet.

This application also there is a version of the website, we will discuss in the next article.

Calculation of Qibla Direction for Indonesian Places

Indonesian Map's

Indonesia is located on the east of the Ka'ba, and is in the south of the Ka'ba, so in logical direction, the direction of the qibla in Indonesia leads to the North West. there are some data that must be searched first to calculate the direction of qibla, that is:

1. Latitude of Ka'ba (φk)
2. Longitude of Ka'ba (λx)
3. Latitude Place (φx)
4. Longitude Place (λx)

For Latitude and Longitude data Ka'ba is usually constant / fixed, but some people vary in its determination, one of the Ka'ba coordinate value ​​used is 21˚ 25 ' 21,01" N and 39˚ 49' 34,33" E. For coordinate data for the place can be searched with various tools, such as GPS. visit this link. Determine Coordinate with GPS.

This calculation uses the assumption that the Earth is a sphere, so this way using the Spherical Algorithm theory. The steps must be taken as follows:

1. Finding the longitude difference (λd) with the formula : λd = (λx - λx).
2. Finding the qibla direction angle (QD) with the formula: Cotan QD = Tan φk * Cos φx / Sin λd - Sin φx / Tan λd.
3. Then finding qibla azimuth value (QA) with the formula: QA = 360 - QD

Average Qibla Azimuth of Indonesia

The direction of the Qiblah that we count, measured from the True North clockwise to the value of the azimuth angle. For the example calculations will be discussed at the next session.

Advantages and Disadvantages of Handheld GPS

Advantages and Disadvantages of Handheld GPS

Actually there are many types of GPS, not just handheld / portable GPS, but also GPS Navigation and GPS Smartphone. For the first of these I will discuss in advance about the GPS handheld, and now I will explain the advantages and disadvantages of GPS handheld.

Handheld GPS

GPS handhelds have a high sensitivity in receiving GPS signals and some devices are capable of receiving dual satellite systems from GPS and Glonass. We can also determine the height of place and direction in an area with satellit signal, there are also various additional sensors, for example barometric altimeter and electronic compass so that the determination of height and direction can be done without using satellite signal. This is usually an option in the settings.

The use of barometric altimeter sensors usually must first be done altitude calibration somewhere. We can also use this barometric altimeter to plot air or ambient pressure from time to time, which can help to observe changes in weather conditions.

The advantage of this GPS compass is that it is not influenced by the magnetic field and can guide the direction accurately as it is guided by signals from the satellites (not the buit-in compass sensor). This tool is certainly very helpful when measuring the direction of Qibla.

The area is remote with no phone signal and does not have internet. We recommend choosing a handheld GPS device. Maps are already stored inside, though the images are very standard, such as the appearance of road maps and soil contours, the data maps in the handheld GPS more complete, but usually sold separately (for each country) and the price is quite expensive. Maps do not need to be installed or downloaded. Because portable GPS has been installed one country map when marketed.

GPS handheld is better, more durable, waterproof and suitable for outdoor activities. Users need not be afraid of the natural conditions, because handheld GPS devices or portable GPS are designed for nature activities. Using this GPS we can find the way when through high-sensitivity wilderness, which acquires satellite signals quickly and tracks locations in challenging conditions such as trees and cliffs.

The battery can be replaced because it uses AAA batteries. One portable GPS device can last up to 25 hours. Very suitable for adventure activities in areas far from electrical energy.

But the obstacle, GPS handheld in terms of price is still quite expensive, for a GPS device ranges between Rp. 2,000,000.00 to Rp.10.000.000,00 or about $ 150 USD to $ 750 USD.

The disadvantages of all GPS, including GPS handhelds are GPS will greatly affect the geographical conditions of where we are. GPS will work well if where we are still has a wide sky. The following will be described wherever the GPS will experience a weakness in its use:

1.When someone is in the forest. With the conditions of the trees are so much then the signals that can be received will be a little maybe even no depending on the width of the forest.
2.When someone is in the water or when someone is diving. Do not expect to use this tool when diving.
3. Electronic devices that can emit electromagnetic waves may affect performance degradation rather than GPS.
4. Buildings. Not only when inside the building, being between 2 tall buildings will also cause an effect like being in a valley.
5. Signals that bounce, eg when in between high-rise buildings, can disrupt the calculation of navigation tools so that navigation tools can indicate the wrong position or not accurate.
6. Glass film car, especially metal-containing.

Menus and Functions on GPS : Garmin 76 C/CSX

I will explain about some menus or functions on the GPS. This time I use GPS Garmin 76 C/CSX. Some GPS devices also have a similar functions.

GPS Garmin 76 C / 76 CSX

1. Key Functions

Inside GPS 76 C there are several buttons that work include to:
A. Power button: Turns the unit on or off. If this button is pressed and released, it can work to adjust the backlight.
B. Zoom In / Out button: To set the size of the scale.
C. Find Button: To go to find menu page and display mob.
D. Quit button: To cancel data entry or close the page.
E. Page or Compass button: To go to the main page and turn the electronic compass off.
F. Menu Button: To enter options, confirm messages or data on-screen. This button can also be used for marking Sign and Waypoint.
G. Rocker Keys: To start moving lists, highlight fields, on-screen buttons, icons, enter data or move to the map section.

2. Getting Satellite Data

For the process of revenue data from satellite, then we must pay attention to the place and condition around. It is advisable to use the GPS in the open and have a wide view. The weather conditions must also be in good condition. For the steps are:
A. Turn on the GPS by pressing the power button. If the GPS has been turned on then it will say "Welcome". The page will quickly face the satellite page.
B. Observe the satellite page and GPS status message when it appears at the top of the page, and soon it will look like a GPSmap. This indicates it will start to search for satellite exploitation status. Not long after that will automatically show our position (latitude and longitude). Visit Determine Coordinate of Place with GPS for more info.

3. Selecting a Page

For all required information or data can be found in four main pages (display screen). These pages include satellites, maps, pointers, and menus. The trick is to press the page button to find the pages.
A. Satellite page: provides a reference for tracked satellites.
B. Page trip computer: provides data and information related to the science of shipping.
C. Page map: provides a view of a map and reference our navigation movement.
D. Page compass: provides guidance for a purpose and direction.
E. Page altimeter: provides path and pressure elevation.
F. Main menu: an existing directory in GPS to specify other settings.

4. Define Waypoint

Waypoint is a marking of places obtained by satellites in a GPS. To mark a place, we can access in the Find Menu by:
A. Press the page button and select the menu page. Press the Up or Down button and select the "Mark" section.
B. Press the enter key. The mark waypoint page will appear with the word "OK?", Hit enter. Waypoint has been stored in GPS memory.

5. Go to the Waypoint Menu
To enter the waypoint we have marked, then we use the Go To facility. How to use it is:
A. Press the page button and select the menu page. Press Up or Down button and select "waypoint". Press Enter. The waypoint page will appear.
B. Press the Up or Down button and select the tab that contains the desired waypoint name and press Enter. The existing waypoint review page will appear.
C. Press Up or Down button to select "GoTo" and press Enter.

6. Exploration on a Waypoint
In the use of the "Go to" facility, we will be directed to follow the directions on the waypoint. The directions provided are N, S, E, W (North, South, East, West). If we cancel, we can use the compass pointing stick to divert the direction toward us. The steps are:
A. Press the page button repeatedly until the compass page is shown. This page contains a bookmark that marks the direction to go.
B. Press the quit button to move to the map page and watch our progress toward the waypoint. The pointer line will show the map and the position arrow movement as we move it.
C. Press the quit button again to move to the travel page. This page provides travel data such as a travel odometer, maximum speed, and more.
D. To stop navigation, press Menu then select stop navigation and then press Enter.

7. Cleaning Track Log
If we have used GPS for multiple trips, then the map view will be full because storing tracks or paths that we have been through. To use this facility the way is:
A. Press the page button and select the menu page.
B. Press Up or Down button and select "Tracks".
C. Press Enter. Use the Up button and select "Clear". Press Enter.

8. Using Map Page 
To use the map page can be done by:
A. Press the page button to go to the main page to the map page.
B. Press the menu button to navigate to the map page selection.
C. Start moving and observing the position arrow on the top of the map. Use the Rocker button to move and move highlights a map item or look into other map areas.

Determine The Coordinates of a Place with GPS.

In the calculation of Islamic Astronomy, the thing that is always required is the coordinates of a place. Many ways and tools can be used to know these coordinates. One of the most famous ways is using GPS (Global Positioning System)

GPS is a navigation and positioning radio system that utilizes satellites as a means of communication. This tool is usually used in vehicle navigation, be it land, sea or air vehicle. Ship and aircraft communication with the station is needed, in order to avoid accidents. GPS is used to know each ship or aircraft position, then reported to the tower / station supervisor at the nearest port or airport.

This GPS will monitor signals from satellites, then GPS will accept the position of the place be it latitude, longitude or altitude place on Earth.

In the Islamic Astronomy, GPS that easy to use is a type of handheld GPS that can be taken anywhere.

GPS has a different level of accuracy, depending on the brand and type of GPS. but overall the tool is quite accurate in determining the coordinates of a place or area.

In this explanation, I will practice using GPS Garmin 72H, but overall, various GPS has a similar way to operate GPS for coordinate determination. The way is :

1. Turn on the GPS in the field, not in the room, around tall buildings, tunnels, and dense forests.

2. Wait a while, about 1-3 minutes, so that GPS receives satellite to make configuration latitude, longitude and altitude data complete.

3. The minimum number of satellites captured to generate coordinates is 4 satellites. And wait a while until the "Location" or "Accuracy" sign shows the smallest number. That sign is the maximum error of the GPS point being, which is predicted by GPS satellite.

4. Then record the coordinates that appear.

Garmin GPS 72H
Souce : https://www.amazon.com

Example image above, the resulting coordinates are 38 degrees 51,498 minutes North Latitude (N) and 94 degrees 47.838 minutes West Longitude (W).

5. if you want to know the height of the place, press the "page" several times until entering on the page high information place.

Good luck!