English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We present radio observations of the Moon between $35$ and $80$ MHz todemonstrate a novel technique of interferometrically measuring large-scalediffuse emission extending far beyond the primary beam (global signal) for thefirst time. In particular, we show that (i) the Moon appears as a negative-fluxsource at frequencies $35<\nu<80$ MHz since it is `colder' than the diffuseGalactic background it occults, (ii) using the (negative) flux of the lunardisc, we can reconstruct the spectrum of the diffuse Galactic emission with thelunar thermal emission as a reference, and (iii) that reflected RFI(radio-frequency interference) is concentrated at the center of the lunar discdue to specular nature of reflection, and can be independently measured. OurRFI measurements show that (i) Moon-based Cosmic Dawn experiments must designfor an Earth-isolation of better than $80$ dB to achieve an RFI temperature$<1$ mK, (ii) Moon-reflected RFI contributes to a dipole temperature less than$20$ mK for Earth-based Cosmic Dawn experiments, (iii) man-madesatellite-reflected RFI temperature exceeds $20$ mK if the aggregate crosssection of visible satellites exceeds $80$ m$^2$ at $800$ km height, or $5$m$^2$ at $400$ km height. Currently, our diffuse background spectrum is limitedby sidelobe confusion on short baselines (10-15% level). Further refinement ofour technique may yield constraints on the redshifted global $21$-cm signalfrom Cosmic Dawn ($40>z>12$) and the Epoch of Reionization ($12>z>5$).

Lunar occultation of the diffuse radio sky: LOFAR measurements between 35 and 80 MHz