# Astrosat

> Indian space observatory

**Wikidata**: [Q298058](https://www.wikidata.org/wiki/Q298058)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/AstroSat)  
**Source**: https://4ort.xyz/entity/astrosat

## Summary
Astrosat is India's first space observatory, launched in 2015 to study the universe in multiple wavelengths, including ultraviolet, visible, and X-ray. Operated by the Indian Space Research Organisation (ISRO), it aims to conduct deep-space research and observe high-energy phenomena such as black holes and neutron stars. It is notable for its multi-instrument design, enabling simultaneous observations across different spectra.

## Key Facts
- **Launch Date**: September 28, 2015, aboard a Polar Satellite Launch Vehicle-XL (PSLV-XL) from Satish Dhawan Space Centre.
- **Operator**: Indian Space Research Organisation (ISRO).
- **Mass**: 1,513 kilograms.
- **Orbit**: Low Earth orbit (near-equatorial).
- **Mission Objective**: To study astronomical objects in ultraviolet, visible, and X-ray wavelengths.
- **Instruments**: Includes the Cadmium Zinc Telluride Imager (CZTI), Soft X-ray Telescope (SXT), Large Area X-ray Proportional Counter (LAXPC), and Ultraviolet Imaging Telescope (UVIT).
- **Identifiers**: COSPAR ID 2015-052A, NORAD ID 40930.

## FAQs
### Q: When was Astrosat launched?
A: Astrosat was launched on September 28, 2015, using the PSLV-XL rocket from the Satish Dhawan Space Centre in India.

### Q: What is the primary purpose of Astrosat?
A: Astrosat was designed to study celestial objects in multiple wavelengths, focusing on high-energy phenomena such as black holes, neutron stars, and supernovae.

### Q: Is Astrosat still operational?
A: As of the last update, Astrosat remained operational, though specific details about its current status depend on ISRO's mission extensions and health assessments.

## Why It Matters
Astrosat represents a significant milestone in India's space science program, marking the country's entry into the domain of space-based astronomy. Its ability to observe the sky in multiple wavelengths allows scientists to study cosmic phenomena in unprecedented detail, contributing to global astrophysical research. By providing data on X-ray binaries, active galactic nuclei, and stellar evolution, Astrosat enhances understanding of the universe's high-energy processes. It also demonstrates ISRO's technological capability to design and operate complex space observatories, positioning India as a key player in international astronomy collaborations.

## Notable For
- India's first dedicated multi-wavelength space observatory.
- Carried four co-aligned instruments for simultaneous observations in ultraviolet, visible, and X-ray bands.
- Detected the first-ever ultraviolet light from a neutron star merger (GW170817) in 2017.
- Operated in a near-equatorial low Earth orbit to minimize orbital precession and maximize observation efficiency.
- Collaborative project involving ISRO and India's scientific community, including the Indian Institute of Astrophysics (IIA) and the Tata Institute of Fundamental Research (TIFR).

## Body
### Launch and Deployment
Astrosat was launched on September 28, 2015, at 09:50 UTC from the First Launch Pad of the Satish Dhawan Space Centre in Sriharikota, India. It was deployed into a 550–750 km low Earth orbit (LEO) with a 6° inclination using the Polar Satellite Launch Vehicle-XL (PSLV-XL) rocket. The mission was managed by ISRO, with a planned operational lifespan of five years.

### Instrumentation
The observatory carries four primary instruments:
- **Cadmium Zinc Telluride Imager (CZTI)**: Detects hard X-rays (10–100 keV) using pixelated CZT detectors.
- **Soft X-ray Telescope (SXT)**: Captures soft X-ray images (0.3–8 keV) with a grazing incidence mirror.
- **Large Area X-ray Proportional Counter (LAXPC)**: Measures X-ray timing and spectral properties in the 3–80 keV range.
- **Ultraviolet Imaging Telescope (UVIT)**: Observes in the far-UV (130–180 nm) and near-UV (200–300 nm) bands.

### Mission Objectives
Astrosat's scientific goals include:
- Studying the timing and spectral characteristics of X-ray binaries and active galactic nuclei.
- Investigating stellar evolution through ultraviolet imaging of star-forming regions.
- Observing supernova remnants, galaxy clusters, and other high-energy astrophysical sources.
- Providing complementary data to other space telescopes like NASA's NuSTAR and ESA's XMM-Newton.

### Legacy
Astrosat has contributed to several notable discoveries, such as the detection of polarized X-rays from the Crab Nebula and the observation of a magnetar (4U 0728–25) in 2020. Its data has been used to study the spin of neutron stars, accretion processes in black holes, and the interstellar medium. The mission has also fostered international collaboration, with observing time allocated to researchers worldwide through competitive proposals.

## References

1. [Source](https://www.isro.gov.in/launchers/list-of-pslv-launches)
2. Jonathan's Space Report
3. Freebase Data Dumps. 2013