We present an overview and description of the e -MERLIN Galaxy Evolution survey ( e -MERGE ) Data Release 1 ( DR1 ) , a large program of high-resolution 1.5 GHz radio observations of the GOODS-N field comprising \sim 140 hours of observations with e -MERLIN and \sim 40 hours with the Very Large Array ( VLA ) .
We combine the long baselines of e -MERLIN ( providing high angular resolution ) with the relatively closely-packed antennas of the VLA ( providing excellent surface brightness sensitivity ) to produce a deep 1.5 GHz radio survey with the sensitivity ( \sim 1.5 \mu Jy beam ^ { -1 } ) , angular resolution ( 0 \farcs 2 – 0 \farcs 7 ) and field-of-view ( \sim 15 \arcmin \times 15 \arcmin ) to detect and spatially resolve star-forming galaxies and AGN at z \gtrsim 1 .
The goal of e -MERGE is to provide new constraints on the deep , sub-arcsecond radio sky which will be surveyed by SKA1-mid .
In this initial publication , we discuss our data analysis techniques , including steps taken to model in-beam source variability over a \sim 20 year baseline and the development of new point spread function/primary beam models to seamlessly merge e -MERLIN and VLA data in the uv plane .
We present early science results , including measurements of the luminosities and/or linear sizes of \sim 500 galaxes selected at 1.5 GHz .
In combination with deep Hubble Space Telescope observations , we measure a mean radio-to-optical size ratio of r _ { eMERGE } / r _ { HST } \sim 1.02 \pm 0.03 , suggesting that in most high-redshift galaxies , the \sim GHz continuum emission traces the stellar light seen in optical imaging .
This is the first in a series of papers which will explore the \sim kpc-scale radio properties of star-forming galaxies and AGN in the GOODS-N field observed by e -MERGE DR1 .