Hold your phone flat, turn until the pointer says you are aligned with the satellite's direction, then look up by the elevation angle shown.
On a phone, every upcoming pass on this site's homepage has a Where to look button. It opens a sheet that turns the pass into two plain instructions: which way to face (the azimuth, e.g. SW · 226°) and how high to look (the elevation, e.g. 38°).
Tap Enable compass and the site uses your phone's orientation sensor to show which way to turn — Turn right 18°, Turn left 12° — until you are facing the satellite. Within 6° counts as aligned. The site says nothing is sent anywhere; the heading is used only on your phone.
While the satellite is up, the target updates every second from the same orbital engine used for the pass list, and the sheet says Tracking … now. Before the pass starts (or after it ends), there is no live position to point at, so the compass aims at the pass's high point instead and labels it Aim point · pass high point.
Tip: start facing the direction in the Look line of the pass card, a little before the start time, then swing towards the aim point as it climbs.
A phone compass senses the Earth's magnetic field, so it points to magnetic north. Satellite directions are measured from true north, the direction to the geographic North Pole. The angle between them is the magnetic declination. It changes from place to place and slowly over the years.
This site corrects for it. It calculates the declination for your location with the World Magnetic Model 2025 — the same model many phones use — and adds it to your phone's magnetic heading. If your phone already reports true north (iPhones do), it uses that directly and says so. If the sensor's accuracy is poor (worse than ±20°), it asks you to move the phone in a figure-8 to recalibrate. If the compass is unavailable, you can still use the azimuth and elevation with an ordinary handheld compass.
On a phone, tap Where to look on the next visible pass: the sheet shows azimuth and elevation, and Enable compass gives turn-left or turn-right instructions. Open the tracker on your phone
The compass logic is pure angle arithmetic; it never computes the satellite's position itself, it takes azimuth and elevation from the visibility engine.
1. True heading. trueHeading = magneticHeading + declination. NOAA's definition: declination is the angle between magnetic north and true north, positive to the east. The site calls the WMM-2025 model offline through a JavaScript package, once per location (it only re-queries after you move more than 40 km or the date changes, since declination varies slowly).
2. Smoothing. Phone magnetometers are noisy, so each new heading is blended with the last using a circular low-pass filter with factor 0.25: x = 0.75 cos(prev) + 0.25 cos(new), y = 0.75 sin(prev) + 0.25 sin(new), heading = atan2(y, x). Averaging on the unit circle avoids a jump when the heading wraps from 359° to 0°.
3. Turn instruction. δ = ((target − heading) mod 360), and if δ > 180° subtract 360°, giving the smallest signed turn in (−180°, 180°]. If |δ| ≤ 6°: aligned. Otherwise turn right if δ > 0, left if δ < 0, by round(|δ|) degrees.
Worked example: target azimuth 226° (SW). Your phone reads magnetic heading 200°, and the local declination is +1.0°. True heading = 201°. δ = 226 − 201 = 25° → Turn right 25°. If instead the magnetic heading were 350°, true heading 351°, δ = (226 − 351) mod 360 = 235°, minus 360 = −125° → Turn left 125°, the shorter way round.
True heading = magnetic heading + declination = 90° + (−2°) = 88°.
Right by 20°, because the shortest rotation from 350° to 10° passes through north.
The satellite is still below the horizon, so there is no live position to point at; the high point tells you where it will be most visible.