Give daylight a place in your plan.
UTC inputs; east-positive longitude; bearings clockwise from true north. Refraction, terrain and clouds affect observed daylight. Horizon obstruction is approximate and does not move civil twilight. A phone compass may require calibration and magnetic declination correction. Carry a map and physical compass.
Model details & unit conventions ↗How to choose a campsite: check rules, overhead hazards, drainage and sleeping ground, then use sunrise bearing to place the open end of a tarp.
Magnetic declination: add east declination to a magnetic bearing to get true north. Conversion examples, bearing error per kilometre and a current value source.
Work out how much daylight is left: NOAA sunset assumes 0.833° of refraction, and twilight ends 6°, 12° or 18° below the horizon. Worked example.
Find sunrise and sunset bearings by season and latitude, with a table from 0° to 60° N, and set a tarp’s open end for morning sun or shade.
Lightning safety for hikers from NWS guidance: what counts as safe shelter, the 30-minute rule after thunder, flash-to-bang distance and storm timing.
Estimate daily solar charge from panel watts, equivalent sun hours and charging losses, with angle and cloud scenarios for a 10 W backpacking panel.
Related toolsMap slope