  We present a study of the far-IR properties of a stellar mass selected sample
of 1.5 < z < 3 galaxies with log(M_*/M_sun) > 9.5 drawn from the GOODS NICMOS
Survey (GNS), the deepest H-band Hubble Space Telescope survey of its type
prior to the installation of WFC3. We use far-IR and sub-mm data from the PACS
and SPIRE instruments on-board Herschel, taken from the PACS Evolutionary Probe
(PEP) and Herschel Multi-Tiered Extragalactic Survey (HerMES) key projects
respectively. We find a total of 22 GNS galaxies, with median log(M_*/M_sun) =
10.8 and z = 2.0, associated with 250 um sources detected with SNR > 3. We
derive mean total IR luminosity log L_IR (L_sun) = 12.36 +/- 0.05 and
corresponding star formation rate SFR_(IR+UV) = (280 +/- 40) M_sun/yr for these
objects, and find them to have mean dust temperature T_dust ~ 35 K. We find
that the SFR derived from the far-IR photometry combined with UV-based
estimates of unobscured SFR for these galaxies is on average more than a factor
of 2 higher than the SFR derived from extinction corrected UV emission alone,
although we note that the IR-based estimate is subject to substantial Malmquist
bias. To mitigate the effect of this bias and extend our study to fainter
fluxes, we perform a stacking analysis to measure the mean SFR in bins of
stellar mass. We obtain detections at the 2-4 sigma level at SPIRE wavelengths
for samples with log(M_*/M_sun) > 10. In contrast to the Herschel detected GNS
galaxies, we find that estimates of SFR_(IR+UV) for the stacked samples are
comparable to those derived from extinction corrected UV emission, although the
uncertainties are large. We find evidence for an increasing fraction of dust
obscured star formation with stellar mass, finding SFR_IR/SFR_UV \propto
M_*^{0.7 +/- 0.2}, which is likely a consequence of the mass--metallicity
relation.
