During an ACES secondment, Bignall, Hayley (S&A, Kensington WA) collected data from the BETA array, looking for peak in the lag spectrum and its variation with angle from the sun and projected baseline length. The result is the contour plot shown here. This can be interpreted in terms of the antenna geometry, also shown here. There are two areas of the plot showing strong solar interference: both on short baselines, one within ~25 deg of antenna pointing, and the other between 90 deg and 130 deg. The antenna diagram shows how the sun directly illuminates the PAF from 90 deg, until the main reflector's shadow falls on the PAF near 130 deg from pointing direction. More information can be found in the following JIRA issue:
ACES-1 - Getting issue details... STATUS
In recent imaging tests, Lenc, Emil (S&A, Marsfield) and others have verified that applying a cut to the visibilities based on a minimum UV distance of about 200 wavelengths is sufficient to mitigate the effects of Solar interference. Other strong sources (at the 1000 Jy level) also cause visible fringes in our observations, so it may be difficult to avoid all such interference from celestial sources. Survey teams should assess whether the shortest baselines are truly needed for their science goal and discard if possible or understand that scheduling windows will be narrowed significantly when looking for faint, diffuse emission.
The ACES team will attempt to verify that the above predictions are still valid for the ADE system and then quantify the impact of Solar interference in the image domain to determine when scheduling constraints are necessary.
ACES-442 - Getting issue details... STATUS