Overview

The Ginga (ASTRO-C) satellite is a Japanese X-ray astronomy satellite launched on February 5, 1987, with the aim of advancing X-ray astronomy. It was launched by the M-3SII rocket No. 3 and was placed in an orbit with a perigee of 530 km, an apogee of 595 km, an inclination of 31 degrees, and a period of 96 minutes. The satellite has a total weight of 420 kg and a maximum solar power generation capacity of 500 watts.

The satellite is equipped with various systems including power, data processing, attitude control, communications, and observation instruments. Notably, it was the first to adopt a bubble memory data recorder (BDR), CCD star sensor (STT), and CCD sun sensor (NSAS), achieving three-axis attitude control.

Observation Instruments

Large Area Counter (LAC)

The LAC is the primary observation instrument of the Ginga satellite, capable of observing time variations in X-ray intensity with high precision. This large-area proportional counter was used to probe the structure of X-ray sources and boasted the highest sensitivity in the world at that time. Calibration was conducted using standard X-ray sources such as the Crab Nebula.

Gamma-ray Burst Detector (GBD)

The GBD consists of a NaI scintillation counter and a proportional counter, designed to detect gamma-ray bursts. This instrument had a high sensitivity for detecting sudden gamma-ray emissions and contributed to the study of high-energy phenomena occurring in space.

All-Sky Monitor (ASM)

The ASM is an all-sky monitor composed of two proportional counters equipped with slit mesh collimators. By periodically rotating the satellite and observing a wide portion of the sky, it monitored X-ray sources showing long-term intensity variations and discovered numerous new X-ray novae.

Achievements

Shortly after its launch, the Ginga satellite observed supernova SN1987A, which appeared in the Large Magellanic Cloud, obtaining high-precision X-ray observational data using the LAC. The ASM discovered many new X-ray novae, and the GBD observed numerous gamma-ray bursts, contributing significant findings to the field.

The observation instruments on the Ginga satellite were developed in collaboration with international partners, including the University of Leicester in the UK for the ASM and Los Alamos National Laboratory in the USA for the GBD. This international cooperation brought many researchers to Japan and facilitated visits abroad by Japanese researchers, promoting the development of instruments and data analysis.