Satellite & Meteor Chaser Pro

Track the International Space Station, satellites and meteor showers from anywhere — with no
signal, no account and nothing to sign up for.

OFFLINE — NO SIGNAL REQUIRED
A complete SGP4 and SDP4 orbital propagator runs on your phone. Pass times, pointing directions
and meteor rates are all computed on the device, so the satellite tracker keeps working in a
valley, in a desert, on a mountain, or anywhere your phone says "No service". Over 200 orbital
element sets ship inside the app, so it works the moment you install it.

TRACK BY EAR — KEEP YOUR NIGHT VISION
Staring at a bright screen destroys the dark adaptation that takes twenty minutes to build up.
So put the screen away and find your target by listening:

• Pitch rises from a low hum to a clear tone as you swing onto the satellite
• The sound leans towards the side you need to turn
• Pulses speed up as you close in, then hold steady when you are on target
• Spoken guidance: "ISS acquisition in 60 seconds. Maximum elevation 72 degrees, west."
• It even tells you to look near Vega, rather than quoting you a bearing

ALERTS THAT GET YOU OUTSIDE IN TIME
A notification a few minutes before anything on your list comes over, with which way to face and
how high it will climb. Choose how far ahead you are warned, and whether to hear only about
passes that will actually be visible. A home-screen widget shows the next pass and tonight's
meteor rate at a glance.

NIGHT ASTRO MODE
Deep red on pure black. Red light barely touches the rod cells your night vision depends on, and
on an OLED screen black pixels are genuinely switched off, so it saves battery too. One tap
switches to a high-contrast daylight mode for planning in the afternoon.

WHAT YOU CAN FIND
• International Space Station, Tiangong, Hubble and over 200 of the brightest satellites
• Every pass, with rise and set directions, peak elevation, duration and brightness
• Honest visibility: the app tells you when a pass is in the Earth's shadow or lost in daylight,
instead of sending you outside for nothing
• All thirteen major annual meteor showers — Perseids, Geminids, Quadrantids, Orionids, Leonids
and the rest
• Over 300 naked-eye stars plotted on the sky chart, so the screen matches the real sky

METEOR RATES YOU CAN ACTUALLY TRUST
Most apps quote the ZHR, a textbook figure that assumes a perfect radiant directly overhead in a
flawless sky. It is almost always several times too optimistic. This app calculates what you will
really see from where you are standing, accounting for:

• How high the shower's radiant sits in your sky right now
• Your local light pollution, on the Bortles scale
• Moonlight — phase and altitude both
• Residual twilight
• How near the shower is to its peak

It will also work out the best hour to be outside tonight.

BUILT FOR THE FIELD
• Works entirely offline, always
• Orbital data refreshes by itself when you next reach Wi-Fi — never on mobile data
• Phones and tablets, portrait and landscape, every orientation
• Under 2 MB installed
• No ads, no tracking, no analytics, no account
• Eleven languages: Spanish, Portuguese, German, French, Japanese, Chinese and more
• Approximate location only — the app never asks for your precise position
• Your location never leaves your device

ACCURACY, HONESTLY
The orbital propagator matches the reference implementation to under a metre, so the real limit
is the age of the orbital elements it is fed. Fresh data gives pass times good to a second or
two; after a couple of weeks a low-orbit pass can drift by tens of seconds. The app shows how old
its data is and warns you when it is getting stale.

Orbital element sets come from CelesTrak (US Space Force 18th Space Defense Squadron, public
domain). Star positions come from the Yale Bright Star Catalogue. Meteor shower parameters follow
the International Meteor Organization working list.

Made for stargazers, hikers and anyone who has ever stood in a dark field wondering
which moving light is the space station.