Localizing a Second
Repeating FRB
The Canadian Hydrogen Intensity Mapping
Experiment telescope and Fast Radio Burst
detector (CHIME/FRB) at the Dominion Ra-
dio Astrophysical Observatory in British Co-
lumbia has proven to be the most prolific
FRB-detecting machine. Since 2018, the tele-
scope's large collecting area, wide band re-
ceiver, and enormous field of view has led to
the discovery of many new repeating FRBs
(CHIME/FRB Collaboration et al., 2019a,b), in-
cluding eight in August 2019.
One of the discovered repeating sources is
FRB 180916. J0158 + 65. The CHIME/FRB Col-
laboration refined the source’s position to a
few arcminutes in the sky. This source exhib-
Figure 1.
The interferometric
localization of FRB
180916.J0158+65 using
the EVN. Panels a to d
show the images of the
four detected bursts.
Panel e shows the
continuum radio image
of the field, where no
significant persistent
radio counterparts are
reported. Panel f shows
the derived positions
for each of the bursts
(orange circles) and the
averaged final position
(black square), to which
all plots are referred:
α (J2000) = 01h 58m
00.75017s (± 2.3 mas), δ
(J2000) = 65˚ 43‘ 00.3152“
(± 2.3 mas). Error bars
represent 1-σ uncertainty.
6
its a low DM, placing it somewhere between
the Galactic halo and a redshift up to ~ 0.1.
We observed the field of FRB 180916.
J0158+65 on June 19, 2019, with the EVN,
combining data from a total of eight radio
telescopes in real time to reach unparalleled
resolution and sensitivity at 1.7 gigahertz
(GHz). In parallel, we also recorded from the
100-meter Effelsberg telescope in Bad Mün-
stereifel, Germany, high time and frequency
resolution data to directly search for single,
bright radio bursts coming from the source.
During this EVN run, we detected four bursts
from FRB 180916.J0158 + 65, with each burst
lasting for, at most, a few milliseconds. As
shown in Figure 1, the resolution reached
in this observation allowed astronomers to
pinpoint the origin of the
bursts in the sky with an
accuracy of about 3 mil-
liarcseconds (Marcote et
al., 2020). Our team found
no persistent radio coun-
terparts consistent with
this position, unlike with
FRB 121102 (the first re-
peater). In archival images
from the Sloan Digital Sky
Survey and PanSTARRs,
this position placed it
at the edge of a diffuse,
seemingly elliptical gal-
axy. Was this repeating
FRB, which is in the same
kind of environment as
the non-repeating FRBs,
drastically different from
that of the first repeater?
With the GMOS imager/
spectrograph on the
8-meter Gemini North
telescope, we observed
this field between July
and September 2019 with
the g and r photometric
GeminiFocus
January 2020 / 2019 Year in Review