MAXI News

One day image of GX 304-1 with psudo-colors (red: 1.5-4 keV, green: 4-10 keV, blue: 10-20 keV)

MAXI/GSC detected an X-ray brightening of the X-ray source GX 304-1. The figure shows one day image of GX 304-1 on 22 March 2009, with pseudo-colors. The preliminary one-day average flux of the source in the 4-10 keV energy band was about 10 mCrab on 21 March and 30 mCrab on 22 March.  We had reported the previous outburst of the source on 15 November 2009 (ATel #2297), which peaked around 19 November 2009.  The interval between the previous and current outburst is consistent with known recurrence period of 132.5 days.

MAXI/GSC continues to monitor the flare of 4U 1608-522. This figure shows the latest light curve.

MAXI/GSC detected an X-ray brightening of the LMXB 4U 1608-522. The figure shows the light curve of this source in 4 – 10 keV band, which was made by image fitting method currently in development. Please be careful about data points before the detection of the flare on March 2 (MJD 55257), because the cause of the baseline offset is not completely understood. Nonetheless, the increase of the flux must be true. We have reported the news to Astronomers Telegram #2462.

To be frank with you, we made a mistook about author list, when we post the telegram. The author list should be as follows:

M. Morii (Tokyo Tech), H. Negoro (Nihon U.), M. Suzuki (JAXA), Y. Ueda (Kyoto U.), M. Matsuoka, K. Kawasaki, S. Ueno, H. Tomida, M. Ishikawa (JAXA), T. Mihara, M. Kohama, Y.E. Nakagawa, M. Sugizaki, T. Yamamoto, T. Saotome (RIKEN), N. Kawai, K. Sugimori (Tokyo Tech), A. Yoshida, K. Yamaoka,  S. Nakahira (AGU), H. Tsunemi, M. Kimura (Osaka U.), M. Nakajima, S. Miyoshi, H. Ozawa, R. Ishiwata, (Nihon U.), N. Isobe, S. Eguchi, K. Hiroi (Kyoto U.), A. Daikyuji (Miyazaki U.), A. Uzawa, T. Matsumura, K. Yamazaki (Chuo U.) report on behalf of the MAXI team

MAXI/GSC detected an X-ray burst from LMXB Aql X-1 from 15:48:40  to 15:49:14 on March 1st, 2010 (UT) during  one scan. The burst flux was about 800 mCrab in 4 – 10 keV band.  The left figure shows the light curve of Aql X-1 taken by two GSC cameras. Here, the flux was calculated by an image fitting method using unbinned maximum likelihood, which is now under development. The upper-right  figure shows the light curve of this X-ray burst during the one scan. The blue and red histograms show count rate (counts per bin) in 4.0 – 10.0  and 1.5 – 4.0 keV bands, respectively.  The bottom-right  figure shows the change of effective area of the GSC cameras. During the scan the hardness ratio between these bands were constant, contrary to the expectation for type I X-ray bursts. It is due to the end of the scan of the GSC cameras, as shown in the bottom-right figure.