Qibla in Kabupaten Tapanuli Selatan

How this is calculated, and how to use it

The qibla is the initial great-circle bearing (the shortest path over the Earth's surface) from your coordinates to the Kaaba (21.4225° N, 39.8262° E), in degrees from true north, measured clockwise: 0° north, 90° east, 180° south, 270° west.

Using the map. The green line on the map points to the qibla. Line it up with the streets, fences or walls around you; this is not affected by magnetism.

Using your phone's compass. A phone compass points to magnetic north and can be off by several degrees near metal or magnets, or when poorly calibrated. Keep it away from metal, calibrate it with a figure-of-eight motion, and compare with the qibla of a nearby mosque.

If this differs from your local mosque, ask the mosque or your local religious authority.