Possible detection of solid formaldehyde towards the embedded source GL 2136

We present new medium resolution spectroscopy (λ/Δλ≊1000) between 3.37 and 3.66 μm towards the deeply embedded source GL 2136. Besides an absorption feature at 3.535 μm due to solid CH3OH which was ealier observed towards other embedded sources, a new feature is apparent at 3.477 μm. From comparison with laboratory data of low temperature ices, we tentatively assign this feature to solid formaldehyde. Our dats combined with earlier observations of CO and H2O indicate towards GL 2136 an ice composition of H2O : CH3OH : H2CO : CO =100 : 3.6 : 2.5 : 3.0.