1999/02/23 by J. J. M. in 't Zand, J. J. M. in ’t Zand, Zand, J. J. M. in 't +22 · 1 citation
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Gamma-ray bursts and supernovae #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9902319
10 pages, accepted for publication in A&A
arxiv created 1999/02/23 · openalex publication_date 1999/02/23 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
For the second time in 27 years a bright transient X-ray source has been detected coincident with the globular cluster NGC 6440. It was found to be active in August, 1998, with the Wide Field Camera and the narrow field instruments on the BeppoSAX spacecraft, and with the All-Sky Monitor and the Proportional Counter Array on the RossiXTE spacecraft. Four X-ray bursts were detected, at least one of which shows the characteristics of a thermonuclear flash on a neutron star, in analogy with some ~20 optically identified low-mass X-ray binaries. The broad-band spectrum is hard as is common among low-mass X-ray binaries of lower luminosity (>~1037 erg/s) and can be explained by a Comptonized model. During the burst the >30 keV emission brightened, consistent with part of the burst emission being Compton up scattered within ~1011 cm.