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VLT optical observations of V821 Ara(=GX339-4) in an extended "off" state

T. Shahbaz·R. Fender·P. A. Charles
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Abstract

We report on low-resolution spectroscopy of GX339-4 during its current, extended X-ray `off' state in May 2000 (r=20.1) obtained with the VLT Focal Reducer/low dispersion Spectrograph (FORS1). Although we do not positively detect the secondary star in GX339-4 we place an upper limit of 30 percent on the contribution of a ``normal'' K-type secondary star spectrum to the observed flux. Using this limit for the observed magnitude of the secondary star, we find a lower limit for the distance of GX339-4 to be 5.6 kpc.

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T. Shahbaz, R. Fender, P. A. Charles. 2001-07-24. VLT optical observations of V821 Ara(=GX339-4) in an extended "off" state. https://doi.org/10.1051/0004-6361%3A20011042

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