At UTC 2019-08-06-17:07:58.0 (2019-08-06.7138657407), we found a fast radio burst as part of the ongoing search program (UTMOST), at the Molonglo telescope.

Molonglo is a 1.6 km long East-West array (Bailes et al 2017, PASA, 34, 45) and was operating in drift-scan mode with pointing centred on the meridian at the time of detection. Source localisation is excellent in Right Ascension (5 arcsec at 1-sigma) but poor in Declination (~1.2 deg at 1-sigma) (see Caleb et al 2017 MNRAS 468, 3746).

FRB190806 was found during a blind FRB search programme in real-time using an automated GPU-accelerated/machine learning-based pipeline and the raw voltages were recorded for offline processing.

The optimal dispersion measure (DM) that maximizes the signal-to-noise ratio is: 388.5 pc cm^-3. The DM estimate of NE2001 model is ~30.8 pc cm^-3, and YMW16 model is ~21.57 pc cm^-3 at this position, resulting in an intergalactic excess of ~357.7 pc cm^-3. The upper limit on the DM-inferred redshift is thus z ~ 0.32.

An early estimate (lower limit) of the event’s apparent fluence is ~46.8 Jy ms (corrected for attenuation of the primary beam in the RA direction, but not in the Dec direction), width ~ 11.96 ms, with a detection signal-to-noise ratio = 14.4.

The most likely position is RA = 00:02:21.38, DEC = -07:34:54.6, J2000, Galactic: Gl = 89.92 deg, Gb = –67.25 deg. The 95% confidence localisation arc is as follows: (RA, DEC) in (hours, deg)

0.038811 -9.936472
0.038914 -9.435500
0.039014 -8.934500
0.039114 -8.433500
0.039211 -7.932528
0.039306 -7.431528
0.039397 -6.930528
0.039489 -6.429556
0.039578 -5.928556
0.039664 -5.427556
0.039750 -4.926583

A formula describing the localisation arc is:

RA = 0.03926 + 0.000189*(DEC +7.68202) – 4.01486e-06*(DEC +7.68202)**2

where RA is in hours, Dec is in deg, and is valid in the range Dec = [-11.94,-3.42].