ISS Transit Finder & Tracker

Find ISS transits across the Sun and Moon, plus a live ISS map and launches.

ISS Transit Finder & Tracker is an astronomy app for Android phones and tablets that predicts when the International Space Station, the Hubble Space Telescope or the Tiangong station crosses in front of the Sun or the Moon, as seen from the location you choose.

A transit almost always lasts under 2 seconds, so timing and position are everything. The app finds these rare alignments and shows where to stand to see or photograph one. It also tracks the ISS live on a world map and lists upcoming rocket launches and space news.

WHAT IT DOES
• Transit finder: the ISS, Hubble and Tiangong crossing the Sun and/or the Moon, with solar and lunar filters.
• Details for each transit: local date and time, distance to the center line, width of the visibility path, altitude and azimuth, duration and an interactive map.
• Live Station: the ISS on a world map (position refreshed about every 5 seconds), its orbit, the day and night line and the crew in space right now.
• ISS guide: key facts, main modules, a 1998 to 2030 timeline and how to see the station with the naked eye.
• Launches: worldwide upcoming and past rocket launches with a live countdown and rocket, mission, orbit and launch pad details.
• Reminders: a notification 1 hour before a transit you pick and 30 minutes before a launch. On Android you can also add the event to your calendar.
• Explore: space news headlines (mostly in English), a daily astronomy photo, an agencies directory, links for sky watchers and a glossary.

WHO IT IS FOR AND WHERE IT WORKS
Astrophotographers chasing solar and lunar transits, amateur astronomers and anyone curious about the ISS and rocket launches. It works anywhere on Earth: set your spot by GPS, by tapping the map or by typing coordinates. The interface is in English and Spanish; it follows your device language and you can switch it in Settings.

HOW IT WORKS
1. Set your location, a date range of up to 30 days and how far you are willing to travel.
2. Pick the Sun and/or the Moon, and the ISS, Hubble and/or Tiangong.
3. Tap Find Transits to get every transit within your travel radius. Wide searches can take up to 30 seconds.

Never look at the Sun without a certified solar filter, and never point a camera or telescope at it without one.

FAQ
What is an ISS transit?
It is the moment the International Space Station (or Hubble, or the Tiangong station) passes in front of the Sun or the Moon as seen from one specific place on Earth.

How long does a transit last?
Almost always under 2 seconds, as the app notes, so you need to be in the right place at the right time.

Do I have to be at an exact spot?
Yes. A transit is visible only from a narrow strip of ground. The app shows the width of that strip and how far it is from your search point, and you choose how far you are willing to travel.

How far ahead can it predict transits?
You can search up to 30 days at a time. Predictions beyond about two weeks are approximate and improve as the date gets closer, so check again before the event.

Does it alert me when the ISS is visible overhead at night?
No. Reminders are for the transits and launches you choose. The Station tab shows where the ISS is right now, and the guide explains how to see it with the naked eye.

Does it work without internet?
Transit searches need a connection because the calculation runs on a server. Launches, news, crew and the picture of the day show their last saved data offline once they have loaded before, and reminders you set still fire.

PRIVACY AND PURCHASES
No ads, no accounts and no in-app purchases. Location is optional and is sent only to the calculation server to answer your search. The app sends crash reports so bugs can be fixed.
Predictions are calculated with the SGP4 orbit model and planetary ephemerides.

Developed by Awesome Apps.