Future facilities and deep surveys such as LSST, JWST and WFIRST, will require a network of standards faint enough to avoid saturation and homogenously distributed in both hemispheres. DA white dwarfs have almost pure hydrogen atmospheres and they are the simplest stars to model. The opacities are known from first principles, and for temperatures higher than ∼ 20,000 K, their photospheres are purely radiative and should be photometrically stable. DA white dwarfs are then the best candidates to establish a network of faint spectrophotometric standards. In order to provide standards in the dynamic range of large aperture (d > 4m) telescopes, we collected Hubble Space Telescope WFC3 images and ground-based spectroscopy for 23 DA white dwarfs fainter than r ∼ 16.5 mag, distributed at equatorial and northern latitudes (see Saha et al. in these conference proceedings).