CHIME/FRB — realfast — VLITE

Using realfast (Law et al 2017) and the VLITE-Fast system to localize repeating FRBs detected by CHIME/FRB

Fast Radio Bursts (FRBs) are mysterious, bright, millisecond-long radio bursts, occuring at a rate of ~1000 FRBs per day in the entire sky at a fluence threshold of 1 Jy-ms in the L-band. FRBs are the most prolific transients known, with an observed rate many orders of magnitude higher than, for example, the gamma-ray burst rate. Even with ~650 FRBs known till date, we have a limited understanding of what FRBs are, what type of objects create them, and whether there are multiple sources of FRBs. Due to their mysterious nature and current lack of constraining observations, a plethora of exotic FRB source models have been proposed (See the FRB Theory Catalog).

Most FRBs are seemingly single flashes, with no repeated bursts being seen with the same dispersion measure (DM) and position in up to a hundred hours of follow-up observations. However, some FRBs emit multiple bursts, sometimes as frequently as hundreds of bursts in a few hours. Since July 2017, the Canadian Hydrogen Intensity Mapping Experiment FRB project (CHIME/FRB) has discovered 18 of the 20 repeating FRBs yet reported (CHIME/FRB Collaboration+, 2019a, 2019b, Fonseca+ 2020a), including the nearest known FRB source, FRB 180916 (Marcote+ 2020).

For the past few years, we have started a long-running program to observe repeating Fast Radio Bursts (FRBs) that are identified by the CHIME/FRB project and localize them with sub-arcsecond precision. The realfast system on the JVLA is built to sample fast visibilities from the WIDAR correlator and search for bursts within the JVLA primary beam (Law et al 2017). JVLA's sensitivity and primary beam size is well-matched for the follow-up of CHIME/FRB detected sources.

The VLA Low Band Ionospheric and Transient Experiment (VLITE) is a commensal system capable of continuously accessing 64 MHz from the new 236-492 MHz Low Band system deployed on the VLA. It uses separate P-band feeds placed at the primary focus of VLA dishes, an independent signal chain, and an independent correlator to make commensal low frequency observations of VLA fields. The VLITE-Fast system additionally searches the low frequency data for short timescale transients.

The combination of realfast and VLITE-Fast provide a wide band coverage of FRBs and improve our search for repeater bursts, which are notorious for being narrow band (while jumping around in frequency). Over 6 semesters, we have observed a dozen repeating FRBs and localized 4 sources and provided deep images of persistent radio sources in their fields. More information on targets and results.


The program is led by Shriharsh Tendulkar (TIFR/NCRA) and Casey Law (Caltech) and supported by the members of the CHIME/FRB collaboration, the realfast collaboration, and the VLITE collaboration. For queries and data access, please contact us via emails (given below):

Shriharsh Tendulkar TIFR/NCRA Mail
Casey Law Caltech Mail
Tracy Clarke NRL/VLITE Mail