GINGA observations of 4U 1820-30 in NGC 6624 : the 11-minute flux modulation.
Abstract
New observations of the X-ray binary source 4U 1820-30 located in the globular cluster NGC 6624 are reported, obtained with the Ginga LAC. The presence of the low-amplitude periodic modulation at a period of 685 sec is confirmed. The average modulation profile is more complex than has been previously observed, with a double minimum, but there is no evidence for any dependence of the profile on X-ray energy. The light curve within each cycle of the 11-min period shows substantial variability which is not consistent with a simple stable modulation.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- 1989
- Bibcode:
- 1989PASJ...41..591S
- Keywords:
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- Ginga Satellite;
- Globular Clusters;
- Light Curve;
- Satellite Observation;
- X Ray Binaries;
- Japanese Space Program;
- X Ray Sources;
- Astrophysics