How to Read the Sky View Diagram
Making sense of the polar plot on each pass card
Every pass card in Ham Sat Tracker includes a circular sky view diagram showing the satellite's track across your sky. At first glance it looks like a radar screen — and it's not far off. Once you know how to read it, the sky view gives you a complete picture of the pass at a glance: where it starts, how high it gets, which direction it travels, and where it ends. Here's how to interpret it.
The Basics: What the Circle Represents
The sky view diagram is a polar plot — a top-down projection of your sky onto a flat circle. Think of it as lying on your back and looking straight up, with the view projected onto paper.
The outer ring is your horizon. The centre is directly overhead. The dashed rings are 30° and 60° elevation.
Reading the Satellite Track
The curved line across the diagram shows the satellite's path through your sky during the pass, running from AOS to LOS with TCA (maximum elevation) marked along the way. Here are the four most common pass shapes you'll see:
High Overhead Pass
Track passes near the centre. Long duration, strong signal. Best passes to work.
Low Horizon Pass
Track hugs the outer edge. Brief window, often blocked by obstructions. Low priority.
East–West Pass
Track sweeps across horizontally. Good mid-elevation passes are workable with a directional antenna.
Typical Good Pass
SE to NW, peaking at 55°. Solid duration, strong signal at TCA. Well worth working.
Using the Sky View to Plan Your Pointing
The sky view diagram is most useful before the pass starts. Look at:
- The AOS entry point — face that compass direction before AOS and have your antenna ready at a low elevation angle (10–15°)
- The track direction — plan which way you'll need to rotate as the pass progresses. For a South-to-North pass you'll start pointing South and rotate to face North by LOS.
- The TCA point — this is where you'll need your antenna elevated highest. For a pass peaking at 60° you'll be pointing significantly upward near TCA.
- Obstructions from your location — mentally compare the track against your local horizon. A building to the East means a pass entering from the East will be blocked until the satellite clears the roofline.
If you're using AntTrack for real-time antenna pointing, the sky view gives you a preview of the full arc before you commit to tracking the pass. A quick look tells you whether to bother setting up for a particular pass or wait for a better one later.
The Numbers vs the Picture
The pass card also gives you the AOS, TCA, and LOS azimuths as numbers — 045°, 178°, 312° and so on. For experienced operators these numbers are often enough. But the sky view diagram is faster to parse at a glance, especially when deciding between several pass options or briefing another operator on what's coming.
The two formats are complementary. Use the diagram to understand the shape of the pass and plan your positioning, then use the numerical azimuths for precise pointing during the pass — or let AntTrack handle that automatically.
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