Wang et al. present the first results from a new ASKAP backend, the CRAFT (Commensal Realtime ASKAP Fast Transient) COherent (CRACO) upgrade. CRACO records millisecond time resolution visibility data, and searches for dispersed fast transient signals including fast radio bursts (FRB), pulsars, and ultra-long period objects (ULPO). With the visibility data, CRACO can localise the transient events to arcsecond-level precision after the detection. The paper describes the CRACO system and reports the result from a pilot survey carried out by CRACO at 110-ms resolution during its commissioning phase.

During the pilot survey, CRACO detected two FRBs. The image above shows the interferometric images of these FRBs. The left panel displays the unnormalised images before (left) and at the time of (right) the FRB detection. The right panel presents the normalised (field source subtracted) images at the time of the FRB detection. All images are imaged with a single sample of data with an integration time of 110 ms. Field sources (unrelated radio galaxies) are marked with cyan solid circles, and FRB locations are indicated by yellow dashed circles. CRACO is enabling the team to better constrain the models for FRBs and use them as cosmological probes.