The tracking tapered gridded estimator for the power spectrum from drift scan observations

ABSTRACT Intensity mapping with the redshifted 21-cm line is an emerging tool in cosmology. Drift scan observations, where antennas are fixed to ground and telescope’s pointing centre (PC) changes continuously on sky due earth’s rotation, provide broad coverage sustained instrumental stability needed for intensity mapping. Here, we present Tracking Tapered Grided Estimator (TTGE) quantify power spectrum of signal estimated directly from visibilities measured drift radio interferometric observations. The TTGE uses data different PC estimate a small angular region located around tracking (TC). size this decided by suitably chosen tapering window function that serves reduce foreground contamination bright sources at large angles TC. It possible cover footprint observations using multiple TC, combine spectra increase signal-to-noise ratio. have validated simulations $154 \, {\rm MHz}$ Murchison Wide-field Array We show can recover input model Cℓ within $20 {{\ \rm per\ cent}}$ accuracy over ℓ range 40 < 700.