MAXI/GSC detected a large X-ray flare from the RS CVn II Peg. The peak flux was obtained at the scan at 03:58 on Apr 5th, 2010 (UT), and is about 70 mCrab, which is one of the brightest X-ray flare from this category.
The bottom figure shows a spectrum obtained with GSC at the brightest scan. The spectral shape is resemble to that in another large flare from this source which was observed with Swift at 11:21:52 on 2005 Dec 16 (UT).
Two GSC cameras (A-camera 0 and 3) are currently not operated since March 29, 2010. These are the north cameras and the north part (50 degree in radius) in the all-sky map is blank now. MAXI still covers 80 % of the sky. The blank region moves around the celestial north-pole with the 60-day orbital presession.
All-sky image on 2010 March 30.
MAXI team reported 4 detections of the transient events to Astronomer’s Telegram (ATEL)
in March, 2010.
And MAXI team also reported one short X-ray transient event to GCN: The Gamma-ray bursts Coordinates Network.
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 detected an X-ray transient at 2010-03-11 02:42:38
(UT). Figure shows the 90% statistical error box region. We have
reported the news to Astronomers Telegram #2476.
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.
The MAXI team reported 4 detections of the transient events to Astronomer’s Telegram (ATEL)
in February, 2010.
And the MAXI team also reported one short X-ray transient event to GCN: The Gamma-ray bursts Coordinates Network.
In the last week (21 Feb – 27 Feb),
several transient events were observed by MAXI.
Here, we shortly report two transient events.
Following the previous large X-ray flare (Atel #2444),
Mrk 421 again exhibited a flare on 2010 Feb 23.
The peak flux of this flare reached at a half level of the previous ones.
Another one is the black hole candidate GX339-4.
On 2010 Feb 24, this source exhibitd a soft band enhancement.
The peak flux within 1 scan reached at ~100 mCrab in the soft band.
You can see the latest lightcurves and images of these sources
on MAXI home page http://maxi.riken.jp/sourcelist.html.
(Nakajima)
