Date: Thu, 27 Mar 2003 20:10:24 +0900 From: Makoto Uemura <uemura@kusastro.kyoto-u.ac.jp> Subject: [vsnet-campaign-xray 204] Call for Observations: X-ray observation of V4641 Sgr Call for Observations: X-ray observation of V4641 Sgr Our proposed X-ray observation of V4641 Sgr with XMM-Newton (PI: M. Uemura) has been scheduled as below: Start time: 2003-04-12 21:51:39 UT End time : 2003-04-13 11:44:59 UT Simultaneous observations are encouraged. V4641 Sgr is a black hole X-ray transient, and also a microquasar. As some of you already know, this object has first received much attention in 1999 September, when it showed a luminous, but very short outburst. Renewed activities have been reported in 2000 and 2002. In particular, during the active phase in the last year, we detected a number of optical short-term variations for several months from 2002 May. The nature of V4641 Sgr is still poorly understood. This X-ray observation is for quiescence. However, it is very important to record its behavior in other wavelengths during the scheduled X-ray observations. Considering the high frequency of its active states and the long active state in 2002, we can say that some activities might be detected during the X-ray run. So, simultaneous observations in the optical, infrared, and radio ranges are highly encouraged. If you have any plans for simultaneous observations, please let me know. Of course, close monitoring in April is also encouraged even if it is not accurately simultaneous. Any information will be welcomed. Regards, Makoto Uemura VSNET Collaboration Team Kyoto University === Associated information: http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Xray/gmsgr.html (1999) http://vsnet.kusastro.kyoto-u.ac.jp/vsnet/Xray/v4641sgr02.html The both URLs have adequate charts for observation.
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