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Latest optical and infrared observations of GX 339-4

ATEL # 1027; Michelle Buxton (Columbia University) and Charles Bailyn (Yale University)
on 12 Mar 2007; 18:18 UT
Password Certification: Michelle Buxton (buxton@astro.yale.edu)

Subjects: Infra-Red, Optical, Binaries, Black Holes, Transients

We have been making daily optical and infrared observations of the black-hole candidate and microquasar GX 339-4 since JD 2454123.9 (Jan 22) using ANDICAM on the SMARTS 1.3m telescope at CTIO. Our V, I, J and H-band lightcurves show that, at the beginning of our observations, GX 339-4 had peaked (V ~ 15, I ~ 14, J ~ 12, H ~ 11.5) and has since become significantly fainter (V ~ 16.5, I ~ 16.0, J ~ 15.0, H ~ 14.5). We note that the differences in magnitude over this time period increase with longer wavelengths: (dV ~ 1.5, dI ~ 2.0, dJ ~ 3.0, dH ~ 3.0). The 2007 light curve may be reminiscent of activity seen at the beginning of 2002, where it is believed that non-thermal optical and infrared emission dominated the early periods of the outburst, followed by dominance of emission by the accretion disk (Homan, Buxton, et al. 2005, ApJ, 624, 295). We will continue daily monitoring of GX 339-4 in these wavebands. Our most recent light curves can be seen at http://www.astro.yale.edu/buxton/smarts/light_curves/gx339.html .


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