Possible Optical/Infrared Jet Emission in 4U 1543‐37

We have taken optical and infrared observations during the 2002 outburst of the soft X‐ray transient, 4U 1543‐47. A secondary maximum occurs in the lightcurves during the outburst decline. This feature is much stronger at infrared wavelengths than optical. We have applied single blackbody, multicolor blackbody and broken‐power law models to the optical/infrared spectral energy distribution of the secondary maximum and find that the broken power‐law provides the best fit. We therefore conclude that the secondary maximum emission originates from a jet. We also show the most recent lightcurves of the 2002/2003 outburst of GX 339‐4 in which a secondary maximum appears. This leads us to the conclusion that secondary maxima may be a common occurrence in soft X‐ray transients during outburst decline which appear after the object transitions into the low‐hard state. Infrared observations of such phenomena will give reliable triggers for multiwavelength observations, allowing us to greatly improve our knowledge of...