obs_cfht is a package in the LSST Science Pipelines.
This package provides CFHT/MegaCam-specific configurations and tasks. Documentation is available at https://pipelines.lsst.io/modules/lsst.obs.cfht/index.html.
MegaCam uses the pixel scale 0.185 arcsec/pixel from http://arxiv.org/pdf/0908.3808v1.pdf.