2010ATel.3075....1N

The MAXI/GSC auto transient-alert system has detected a new activity from a binary X-ray pulsar, GX 304-1 on 2010-12-08. The current source activity is the fourth event since the MAXI/GSC observation started on 2009 August. The source flux started to increase on 2010-12-05 (MJD 55535.5) and reached 20 mCrab (2-20 keV) on 2010-12-08 (MJD 55538.5). Comparing with the previous outburst (Atel#2779), the current flux increase is about 1-week earlier than that of the previous one within the orbital cycle of 132.5-day period. Thus, the current activity may be a precursor, or an onset of an anomalous giant outburst that occurs out of regular recurrent phase. In case of A0535+26 (Atel#2970), precursor events are seen in large outbursts (Atel#2970). Among the previous three outbursts from GX 304-1, only the last one, which developed into the giant outburst, had a precursor. Applying this relation, the incoming outburst is supposed to become giant. The latest light curve and folded light curve are available at the following URL:@ http://maxi.riken.jp/top/index.php?cid=1&jname=J1301-616 and also in the news page URL: http://maxi.riken.jp/news/.