On September 28, 2025, India's first multi-wavelength space observatory, AstroSat, completed 10 years of operation. Exceeding its five-year mission life, the observatory continues to provide valuable data to the scientific community.
Recent discoveries and observations
AstroSat's recent contributions include shedding light on the internal structure of neutron stars and detecting X-ray bursts from a magnetar.
It has also observed gas behavior and jet formation around black holes, and in July 2025, identified fast X-ray flickers (QPOs) around a black hole.
The observatory's ultraviolet capabilities have allowed it to witness the formation of dwarf galaxies, and it has provided crucial data on rapidly spinning black holes.
Additionally, AstroSat has collaborated with NASA observatories to study eruptions around a massive black hole.
Decade of discoveries
Since its launch in 2015, AstroSat has made numerous discoveries, including solving a long-standing mystery about a bright red giant star.
It detected extreme ultraviolet light from an early galaxy and has helped characterize star formation in "Jellyfish galaxies".
AstroSat also observed X-ray polarization from the Crab Pulsar and mapped an emission region in the Butterfly Nebula.
Designed to study celestial sources across the electromagnetic spectrum, it provides a unique capability for simultaneous observation in the X-ray, ultraviolet (UV), and optical bands.
This allows scientists to gain comprehensive insights into the same cosmic phenomena at different energy levels.
Key features
Multi-wavelength capability: A primary feature is the ability to observe the cosmos in multiple wavelengths simultaneously. This overcomes the limitations of ground-based telescopes, as Earth's atmosphere blocks out high-energy X-rays and ultraviolet radiation.
Long operational life: Though its designed mission life was five years, AstroSat has continued to provide valuable data and celebrated its 10th anniversary in September 2025.
International collaboration: The project is a collaborative effort involving premier Indian research institutions and international partners from the UK and Canada.
Open observatory: It operates as an observatory-class satellite, with observing time available to the global scientific community through a proposal system.
Scientific payloads
AstroSat carries five specialized instruments for its multi-wavelength observations:
Ultra Violet Imaging Telescope (UVIT): Consists of two telescopes for imaging in far-UV (FUV), near-UV (NUV), and visible bands. It has achieved an angular resolution superior to many other UV telescopes.
Soft X-ray Telescope (SXT): Uses X-ray mirrors and a CCD camera for imaging and spectral studies in the 0.3–8 keV energy range.
Large Area X-ray Proportional Counter (LAXPC): A cluster of three gas detectors designed for X-ray timing and spectral studies in the 3–80 keV band.
Cadmium Zinc Telluride Imager (CZTI): A coded mask camera for hard X-ray imaging (10–100 keV). It is also capable of measuring X-ray polarization.
Scanning Sky Monitor (SSM): An all-sky monitor for detecting and tracking transient X-ray sources.
Scientific objectives
AstroSat is dedicated to a range of astrophysical studies, including:
Black holes and neutron stars: Understanding high-energy processes in binary star systems containing black holes and neutron stars.
Star formation: Studying regions of star birth and the high-energy processes in star systems beyond the Milky Way.
Transient sources: Detecting and monitoring new, briefly bright X-ray sources.
UV surveys: Performing deep-field surveys of the Universe in the ultraviolet region.
Spectroscopic studies: Conducting broadband spectral analysis of various cosmic sources, including X-ray binaries and active galactic nuclei (AGNs).
Key achievements
Discovered an early galaxy: Detected extreme-UV light from AUDFs01, a galaxy located 9.3 billion light-years away, marking a significant breakthrough.
Studied X-ray polarization: CZTI successfully measured X-ray polarization from the Crab pulsar, providing new insights into the radiation mechanisms of gamma-ray bursts (GRBs).
Pioneered high-resolution UV imaging: UVIT provided exceptional high-resolution images, leading to the first detection of young stars in the bulge of the Andromeda galaxy.
Insight into black holes: Its observations have provided deeper insights into the behavior of black holes and their interaction with surrounding matter.
