Ginga (ASTRO-C) All Sky Monitor (ASM) Data Released

ISAS has been restoring the past satellite data launched by ISAS and stored at Japanese universities. Ginga (ASTRO-C) was launched in 1987, and equipped with the main instrument, Large Area Counter (LAC) and also All Sky Monitor (ASM). The LAC observed specific celestial objects in detail with a small field of view. On the other hand, ASM monitored various objects all over the sky by periodically sweeping the sky with a long and thin field of view. From the end of February 1987, Ginga started daily ASM monitoring for about 20 minutes, while the LAC observation was interrupted. Until the end of operation in autumn 1991, ASM obtained 4.5-year X-ray intensity histories of more than 100 objects. The right upper figure shows the intensity history of the black hole candidate GX 339-4, indicating that the object was sometimes extremely bright and sometimes very faint during the mission period. The right lower figure shows the intensity history of an X-ray nova appeared in January 1991, which was named GS1124-683, meaning that it was discovered by Ginga Satellite at RA=11h24m, Dec=−68.3 deg. The ASM raw data had been stored at Osaka and Rikkyo universities for a long time. The data were converted into the standard FITS format and released from DARTS, through collaboration between Rikkyo University and ISAS. (Jan 2018)

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Last Modified: 07 May 2018