Context :

Aims : Qatar-1b is a close-orbiting hot Jupiter ( R _ { p } \simeq 1.18 R _ { J } , M _ { p } \simeq 1.33 M _ { J } ) around a metal-rich K-dwarf , with orbital separation and period of 0.023 AU and 1.42 days .
We have observed the secondary eclipse of this exoplanet in the Ks band with the objective of deriving a brightness temperature for the planet and providing further constraints to the orbital configuration of the system .

Methods : We obtained near-infrared photometric data from the ground by using the OMEGA2000 instrument at the 3.5 m telescope at Calar Alto ( Spain ) in staring mode , with the telescope defocused .
We have used principal component analysis ( PCA ) to identify correlated systematic trends in the data .
A Markov chain Monte Carlo analysis was performed to model the correlated systematics and fit for the secondary eclipse of Qatar-1b using a previously developed occultation model .
We adopted the prayer bead method to assess the effect of red noise on the derived parameters .

Results : We measured a secondary eclipse depth of 0.196 \% ^ { +0.071 \% } _ { -0.051 \% } , which indicates a brightness temperature in the Ks band for the planet of 1885 ^ { +212 } _ { -168 } K. We also measured a small deviation in the central phase of the secondary eclipse of -0.0079 ^ { +0.0162 } _ { -0.0043 } , which leads to a value for e \cos { \omega } of -0.0123 ^ { +0.0252 } _ { -0.0067 } .
However , this last result needs to be confirmed with more data . The light-curve data shown in Fig.3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr ( 130.79.128.5 ) or via http : //cdsweb.u-strasbg.fr/cgi-bin/qcat ? J/A+A/ .

Conclusions :