We present the first wide area (2.5 x 2.5 square degrees), deep (median noise
of approximately 80 microJy per beam) LOFAR High Band Antenna image at a
resolution of 1.2 arcseconds by 2 arcseconds. It was generated from an 8-hour
International LOFAR Telescope (ILT) observation of the ELAIS-N1 field at
frequencies ranging from 120 to 168 MHz with the most up-to-date ILT imaging
strategy. This intermediate resolution falls between the highest possible
resolution (0.3 arcseconds) achievable by using all International LOFAR
Telescope (ILT) baselines and the standard 6-arcsecond resolution in the LoTSS
(LOFAR Two-meter Sky Survey) image products utilizing the LOFAR Dutch baselines
only. This is the first demonstration of the feasibility of approximately 1
arcsecond imaging using the ILT, providing unique information on source
morphology at scales below the surface brightness limits of higher resolutions.
The total calibration and imaging time is approximately 52,000 core hours,
nearly five times more than producing a 6-arcsecond image. We also present a
radio source catalog containing 2263 sources detected over the 2.5 x 2.5 square
degrees image of the ELAIS-N1 field, with a peak intensity threshold of 5.5
sigma. The catalog has been cross-matched with the LoTSS deep ELAIS-N1 field
radio catalog, and its flux density and positional accuracy have been
investigated and corrected accordingly. We find that approximately 80% of
sources that we expect to be detectable based on their peak brightness in the
LoTSS 6-arcsecond image are detected in this image, which is approximately a
factor of two higher than for 0.3 arcsecond imaging in the Lockman Hole,
implying there is a wealth of information on these intermediate scales.Comment: Submitted to A&