  At relatively high frequencies, highly sensitive grating sidelobes occur in
the primary beam patterns of low frequency aperture arrays (LFAA) such as the
Murchison Widefield Array (MWA). This occurs when the observing wavelength
becomes comparable to the dipole separation for LFAA tiles, which for the MWA
occurs at approximately 300 MHz. The presence of these grating sidelobes has
made calibration and image processing for 300 MHz MWA observations difficult.
This work presents a new calibration and imaging strategy which employs
existing techniques to process two example 300 MHz MWA observations.
Observations are initially calibrated using a new 300 MHz sky-model which has
been interpolated from low frequency and high frequency all-sky surveys. Using
this 300 MHz model in conjunction with the accurate MWA tile primary beam
model, we perform sky-model calibration for the two example observations. After
initial calibration a self-calibration loop is performed by all-sky imaging
each observation with WSCLEAN. Using the output all-sky image we mask the main
lobe of the image. Using this masked image we perform a sky-subtraction by
estimating the masked image visibilities using WSCLEAN. We then image the main
lobe of the observations with WSCLEAN. This results in high dynamic range
images of the two example observation main lobes. These images have a
resolution of 2.4 arcminutes, with a maximum sensitivity of 31 mJy/beam. The
calibration and imaging strategy demonstrated in this work, opens the door to
performing science at 300 MHz with the MWA, which was previously an
inaccessible domain. With this paper we release the code described below and
the cross-matched catalogue along with the code to produce a sky-model in the
range 70-1400 MHz.
