XTE J1550-564 = V381 Nor: Microquasar Again in Outburst

(Wide-field image by Berto Monard)

(Close-up view showing the optical counterpart)

Renewed Activity

(vsnet-campaign-xray 205)

XTE J1550-564: renewed activity

According to IAUC 8100, the INTEGRAL satellite detected a new outburst of the black hole binary and microquasar, XTE J1550-564. The object was 150mCrab in the 15-40 keV band and 250mCrab in the 40-100 keV band on March 24.2-25.1. X-ray outbursts of this object have been accompanied by optical, infrared, and radio outbursts. So, multi-wavelength observations are encouraged.

Makoto Uemura
(vsnet-campaign-xray 207)

According to CBET #12, Would et al. found that XTE J1550-564, whose X-ray rebrightening was reported in [vsnet-campaign-xray 205], is now bright in the optical range at V~18. Furthermore, they report the detection of optical rapid variations, including a flare of about 0.5mag lasting < 20s.

Such large-amplitude and rapid variations are reminiscent of V4641 Sgr which also exhibited rapid optical variations in 2002. These rapid optical variations must be from inner accretion flow, or close to the central black hole. Follow-up observations are strongly encouraged. If the component of the rapid variation is synchrotron emission, we can expect some correlations between optical, infrared, and possibly radio variations. So, multiwavelength simultaneous observations are needed.

Makoto Uemura
(vsnet-campaign-xray 209)

According to ATEL #134, E. Kuulkers et al. reported the detection of the new outburst of XTE J1550-564 with RXTE/ASM. The source started to appear around March 29. Between March 29 and 31 the 2-12 keV flux was between 40 and 65 mCrab, with a mean of 55+/-3 mCrab.

Follow-up observations are strongly encouraged.

Makoto Uemura

Monard's observation

(vsnet-campaign-xray 208)
CCD observations of 28 March 2003
observer: Berto Monard  MLF, Pretoria, South Africa
Bronberg observatory / CBA Pretoria
location: -25o 54' 48", 28o 26' 44"E, altitude 1590m
instrumentation: LX200 12" f/4.2 with ST-7E, unfiltered
conditions: clear, moderate seeing

XTEJ1550-564   20030328.91   170CR   MLF
this measurement is traceable to R magnitudes from the Loneos file, kindly provided by B Skiff from published data from Jain et al (2001) vsnet-sequence 117

Astrometry vs uSNO-A2.0 gives a position (2000)

15 51 04.03 -56 28 34.5

XTE J1550-564 is also known as V381 Nor, if I am not mistaken.

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