SuperCLASS -- III. Weak lensing from radio and optical observations in
  Data Release 1
  We describe the first results on weak gravitational lensing from the
SuperCLASS survey: the first survey specifically designed to measure the weak
lensing effect in radio-wavelength data, both alone and in cross-correlation
with optical data. We analyse 1.53 square degrees of optical data from the
Subaru telescope and 0.26 square degrees of radio data from the e-MERLIN and
VLA telescopes (the DR1 data set). Using standard methodologies on the optical
data only we make a significant (10 sigma) detection of the weak lensing signal
(a shear power spectrum) due to the massive supercluster of galaxies in the
targeted region. For the radio data we develop a new method to measure the
shapes of galaxies from the interferometric data, and we construct a simulation
pipeline to validate this method. We then apply this analysis to our radio
observations, treating the e-MERLIN and VLA data independently. We achieve
source densities of 0.5 per square arcmin in the VLA data and 0.06 per square
arcmin in the e-MERLIN data, numbers which prove too small to allow a detection
of a weak lensing signal in either the radio data alone or in cross-correlation
with the optical data. Finally, we show preliminary results from a
visibility-plane combination of the data from e-MERLIN and VLA which will be
used for the forthcoming full SuperCLASS data release. This approach to data
combination is expected to enhance both the number density of weak lensing
sources available and the fidelity with which their shapes can be measured.
