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22nd of September 2021
A VAST Pilot Survey pulsar
by Murphy et al.
The ASKAP Variables and Slow Transients Survey (VAST) is designed to detect highly variable and transient radio sources on timescales from 5 seconds to ∼5 years. Murphy et al. have recently presented initial results from the VAST Phase I Pilot Survey. An initial search revealed 28 highly variable and/or transient sources. One class of variable sources was pulsars, as illustrated in yesterday's ADAP. For this pulsar, variability is most likely due to refractive interstellar scintillation on longer timescales and diffractive interstellar scintillation on shorter timescales. The left panel above shows the VAST Stokes I (total intensity) image for the epoch with the maximum flux density. The middle panel shows the Stokes V (circular polarisation) image for the same epoch where positive flux density corresponds to right handed circular polarisation and negative to left handed. The ellipse in the lower left corner of each radio image shows the FWHM of the restoring beam. The right panels show Stokes I contours at 30, 60, and 90 per cent of the peak Stokes I flux density overlaid on an RGB image of optical data from the Dark Energy Survey with red=i-band, green=r-band, blue=g-band. This pulsar shows negligible circular polarisation, and like most pulsars, is not detectable at optical wavelengths.

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