4U 1820-303 is entering a low/hard X-ray state
Abstract
All sky measurements taken by the RXTE/ASM, MAXI/GSC and Swift/BAT, as well as pointed observations by the RXTE/PCA as part of the Galactic bulge scans, show that the ultra-compact low-mass X-ray binary 4U 1820-303 is entering a low/hard state again. The last low/hard state was seen in April-June 2009 and lasted for about 2 months (ATels #2071, #2167). In soft X-rays (<12 keV) the source is declining steadily in flux over the last days to weeks; it reached about 100-125 mCrab on UT 2010 April 4, approaching the lowest values seen over the last decades.
- Publication:
-
The Astronomer's Telegram
- Pub Date:
- April 2010
- Bibcode:
- 2010ATel.2533....1K
- Keywords:
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- X-ray;
- Request for Observations;
- Binaries;
- Globular Clusters;
- Neutron Stars;
- Variables