AstroSat
AstroSat is India's first dedicated multi-wavelength space observatory — a telescope that studies the same object in X-ray, ultraviolet and visible light at once. It has been working since 2015 — and it shares a name with this site entirely by accident. Naturally, we track it.
What makes AstroSat different
Five instruments, one target
Most observatories see one band. AstroSat carries five payloads — UVIT, SXT, LAXPC, CZTI and the Scanning Sky Monitor — so it can watch a single object in ultraviolet, soft X-ray and hard X-ray simultaneously. For objects that flicker on timescales of seconds, seeing all the bands at once is the entire point.
An orbit chosen for quiet
It flies near-equatorial at about 6° inclination, roughly 650 km up. That keeps it largely clear of the South Atlantic Anomaly, the region of trapped radiation that blinds X-ray detectors — an orbit picked for what it avoids rather than what it covers.
Open to the world
It runs as a proposal-driven general-purpose observatory: astronomers anywhere can apply for observing time. A decade of data on white dwarfs, neutron stars, black holes and active galactic nuclei has come out of it.
About the name
The name of this site was picked because it sounded right for a satellite tracker. Only afterwards did we find out ISRO had got there first, with an actual spacecraft. It is an observatory, we are a tracker, and the happy accident is that we can show you exactly where it is right now — which its own mission pages cannot.
AstroSat launched on a PSLV from Satish Dhawan Space Centre on 28 September 2015 and passed a decade of operations in 2025 — well beyond its original five-year design life. Its scientific case rests on simultaneity: a black-hole binary can change character in seconds, and measuring the ultraviolet and the hard X-ray at the same instant tells you something that two separate telescopes observing hours apart never can. The altitude figure at the top of this page is not from a spec sheet; it is propagated from the same orbital element set that drives the globe, refreshed every two hours, so it moves as the satellite does.
Frequently asked questions
Where is AstroSat right now?
The figure at the top of this page is its live altitude, with its ground position underneath — both computed from current orbital data using the SGP4 model. Open it on the globe to watch it move.
Is AstroSat still working?
Yes. It passed ten years of operation in 2025, well past its five-year design life, and continues to observe on a proposal-driven basis.
Can I see AstroSat from the ground?
Not easily. It is small and at roughly 650 km it is far fainter than the ISS. Its near-equatorial orbit also means it never passes over most of Europe or North America at all.
Is this website run by ISRO?
No. AstroSat.app is an independent satellite tracker with no connection to ISRO. The name was chosen for this site without knowing the satellite existed, which we only discovered later — and we track their observatory along with everything else in the catalogue.
What does multi-wavelength mean?
Different physical processes emit at different energies. A hot accretion disc glows in X-ray while the surrounding star is brightest in ultraviolet, so seeing one band alone gives you a partial picture. AstroSat observes several at once.