We report the tentative detection of the near-infrared emission of the Hot Jupiter WASP-12b with the low-resolution prism on IRTF/SpeX .
We find a K - H contrast color of 0.137 \% \pm 0.054 \% , corresponding to a blackbody of temperature 2400 ^ { +1500 } _ { -500 } ~ { } \textrm { K } and consistent with previous , photometric observations .
We also revisit WASP-12b ’ s energy budget on the basis of secondary eclipse observations : the dayside luminosity is a relatively poorly constrained ( 2.0 - 4.3 ) \times 10 ^ { 30 } erg s ^ { -1 } , but this still allows us to predict a day/night effective temperature contrast of 200 - 1 ,000 K ( assuming A _ { B } = 0 ) .
Thus we conclude that WASP-12b probably does not have both a low albedo and low recirculation efficiency .
Our results show the promise and pitfalls of using single-slit spectrographs for characterization of extrasolar planet atmospheres , and we suggest future observing techniques and instruments which could lead to further progress .
Limiting systematic effects include the use of a too-narrow slit on one night – which observers could avoid in the future – and chromatic slit losses ( resulting from the variable size of the seeing disk ) and variations in telluric transparency – which observers can not control .
Single-slit observations of the type we present remain the best option for obtaining \lambda > 1.7 \micron spectra of transiting exoplanets in the brightest systems .
Further and more precise spectroscopy is needed to better understand the atmospheric chemistry , structure , and energetics of this , and other , intensely irradiated planet .