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optical outburst of 4u 1608-522 (=QX Nor)

ATel #855; Charles D Bailyn (Yale)
on 9 Jul 2006; 16:04 UT
Credential Certification: Charles Bailyn (bailyn@astro.yale.edu)

Subjects: Optical, Binary, Neutron Star, Transient

Referred to by ATel #: 857, 1113

SMARTS consortium observations with the 1.3m telescope at CTIO + ANDICAM instrument show that QX Normae, the optical counterpart of 4U 1608-522, is in outburst (see Markwardt et al. ATEL 851 for a description of the current high energy outburst). We obtained a 12m I-band image starting at UT=2:01 July 9 2006 that showed the optical counterpart to be comparable in magnitude to comparison star #7 (I=18.7) from Wachter 1997 (ApJ 485, 839). Precise measurements were hard to obtain from this image due to bad conditions and scattered light, but QX Nor is clearly well above its quiescent brightness of I>21 (Wachter et al. 2002 568, 901), and within the range of the "Low Intensity State" described by Wachter et al.