  We report transmission spectroscopy of the bloated hot Jupiter WASP-74b in
the wavelength range from 4000 to 6200 \r{A}. We observe two transit events
with the Very Large Telescope FOcal Reducer and Spectrograph (VLT FORS2) and
present a new method to measure the exoplanet transit depth as a function of
wavelength. The new method removes the need for a reference star in correcting
the spectroscopic light curves for the impact of atmospheric extinction. It
also provides improved precision, compared to other techniques, reaching an
average transit depth uncertainty of 211 ppm for a solar-type star of V=9.8 mag
and over wavelength bins of 80 \r{A}. The VLT transmission spectrum is analysed
both individually and in combination with published data from Hubble Space
Telescope (HST) and Spitzer. The spectrum is found to exhibit a mostly
featureless slope and equilibrium chemistry retrievals with PLATON favour hazes
in the upper atmosphere of the exoplanet. Free chemistry retrievals with AURA
further support the presence of hazes. While additional constraints are
possible depending on the choice of atmospheric model, they are not robust and
may be influenced by residual systematics in the data sets. Our results
demonstrate the utility of new techniques in the analysis of optical,
ground-based spectroscopic data and can be highly complementary to follow-up
observations in the infrared with JWST.
