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 filterbank plots for these FRBs. For each burst, figures show the dedispersed pulse profile for the burst (top), the dynamic spectrum for the dedispersed pulse (middle), and signal strength as a function of dispersion measure (DM) and time (bottom). The horizontal stripes correspond to the parts of the band that have been removed due to the presence of radio frequency interference. CRACO is enabling the team to better constrain the models for FRBs and use them as cosmological probes.