GUIDES / BASICS
How to read elevation and azimuth in a pass table
By Jeroen Wouda · 2 November 2026 · Basics
A pass table is short — a handful of times and angles — but it holds everything you need to put yourself in the right place at the right moment. The two numbers people stumble over are elevation and azimuth.
A row is a story in five parts
Most tables give, for each pass:
- the time the station rises above the horizon
- the time it reaches its highest point
- the time it sets
- the maximum elevation, in degrees
- the compass directions it rises from and sets towards
Some add a brightness figure. Read as a sentence, a row says: at this time, look in this direction; by this time it will be this high; and by this time it will be gone.
Times are local, and the pass is short
The start time is the moment the station crosses your horizon — zero degrees of elevation — and the end time is when it drops below it again. The gap between the two is the whole event, and it is measured in minutes, typically between two and seven.
Three practical consequences:
- Be outside before the start time. Setting up during the pass wastes the best part of it.
- The peak time is the best moment. That is when the station is highest and usually brightest.
- The end time is geometry, not brightness. The station can go dark before it reaches the horizon, when it enters the Earth's shadow. A pass that ends abruptly overhead is behaving exactly as orbital mechanics dictates.
Elevation: how high to look
Elevation is the angle above the horizon, measured in degrees. Zero is the horizon and 90 is directly overhead. It is the number that decides whether a pass is worth the trouble.
- Under about 10°: a graze. The station is far away, dim, and behind anything taller than a garden fence. Rarely worth it unless you have a clear sea horizon.
- 10° to 30°: visible and worth going out for, but you need a clean view in that direction. Trees and rooftops eat this band.
- 30° to 60°: comfortable. Easy to find, clearly bright and unhurried.
- Above 60°: the good ones. Close, bright, and passing almost over your head.
Elevation is a decent proxy for brightness, because a higher pass means the station is closer to you, but it is not a guarantee. How the sunlight strikes the station and comes back towards you changes through the pass, and a high pass seen at a poor angle can be dimmer than expected. A lower pass in good light can be surprisingly bright.
Azimuth: which way to face
Azimuth is a compass bearing, in degrees clockwise from north: 0 is north, 90 east, 180 south and 270 west. A table usually gives two — the entry azimuth, where the station appears, and the exit azimuth, where it disappears.
The entry azimuth is the one that matters at the start: face it, and look up. Values between the cardinal points are easy once you have the pattern: 45 is north-east, 135 south-east, 225 south-west and 315 north-west.
Two habits make this much easier:
- Find north properly, once. A compass, a phone or the Pole Star. Guessing in an unfamiliar place at night is unreliable, and being a quarter-turn out is the classic reason people see nothing.
- Turn your whole body, not just your head. Then you look up at a comfortable angle instead of craning.
Putting it together
Read a row in order. The start time gets you outside and facing the entry direction. The peak time tells you when to look highest, the direction being roughly midway between entry and exit. The end time tells you when to give up. The maximum elevation tells you how much of your horizon needs to be clear.
A pass that rises in the north-west, peaks high and sets in the south-east is a different evening from one that stays low in the south for its whole length. The first needs open sky overhead; the second needs a low southern horizon and little else.
Duration is not the same as quality
A pass that skims the horizon can last longer than one that goes straight overhead, because the station travels a longer path across your visible sky. But it is dimmer and more easily blocked, so a short, high pass is usually the better experience even though it gives you less time.
If your table lists brightness
Satellite brightness is given as a magnitude, and the scale runs the wrong way round: a smaller number means a brighter object, and negative numbers are brighter than the brightest stars. If you have the choice between two passes on the same evening, the one with the lower magnitude is the one to take, though a higher elevation and a darker sky will usually matter more.
Why a listed pass can still fail
The table is geometry, and geometry does not account for your weather or your walls. Cloud is the obvious one. A 15° pass behind a block of flats is invisible. And a pass can go dark in mid-sky on entering the Earth's shadow, well before its listed end time.
Read the row, then look at your actual sky. The numbers tell you where the station will be; they cannot tell you whether you will be able to see it from where you are standing.
Where to go next
More guides
- Best time of year to watch the ISS — There is no single best month. The good weeks depend on the angle between the orbit and the Sun, and here is how that cycle works.
- How often does the ISS pass over my city? — The station circles Earth 15 times a day, yet you can go weeks without a visible pass. Here is why the schedule behaves that way.
- How to photograph the ISS — A moving point of light, a dark sky and a camera, and what it takes to turn a pass into a photograph worth keeping.