Context :

Aims : We aim to construct a spectral energy distribution ( SED ) for the emission from the dayside atmosphere of the hot Jupiter WASP-46b and to investigate its energy budget .

Methods : We observed a secondary eclipse of WASP-46b simultaneously in the g ^ { \prime } r ^ { \prime } i ^ { \prime } z ^ { \prime } JHK bands using the GROND instrument on the MPG/ESO 2.2 m telescope .
Eclipse depths of the acquired light curves were derived to infer the brightness temperatures at multibands that cover the SED peak .

Results : We report the first detection of the thermal emission from the dayside of WASP-46b in the K band at 4.2 \sigma level and tentative detections in the H ( 2.5 \sigma ) and J ( 2.3 \sigma ) bands , with flux ratios of 0.253 ^ { +0.063 } _ { -0.060 } % , 0.194 \pm 0.078 % , and 0.129 \pm 0.055 % , respectively .
The derived brightness temperatures ( 2306 ^ { +177 } _ { -187 } K , 2462 ^ { +245 } _ { -302 } K , and 2453 ^ { +198 } _ { -258 } K , respectively ) are consistent with an isothermal temperature profile of 2386 K , which is significantly higher than the dayside-averaged equilibrium temperature , indicative of very poor heat redistribution efficiency .
We also investigate the tentative detections in the g ^ { \prime } r ^ { \prime } i ^ { \prime } bands and the 3 \sigma upper limit in the z ^ { \prime } band , which might indicate the existence of reflective clouds if these tentative detections do not arise from systematics .

Conclusions :