FRB170922 – UTMOST finds the widest FRB yet

On 2017-09-22-11:23:33.4 UTC (2017-09-22.4746921296), UTMOST found a new FRB as part of the ongoing search program at the Molonglo Radio Telescope (see Bailes et al. 2017, arxiv.org/abs/1708.09619). This is the fifth Molonglo FRB overall (See ATel #10697 and Caleb et al. 2017, MNRAS, 468, 3746).

The optimal dispersion measure (DM) that maximizes the signal-to-noise ratio is: 1111 pc cm^-3, which is substantially in excess of the Galactic DM as estimated by the NE2001 (www.nrl.navy.mil/rsd/RORF/ne2001/) model (~ 45 pc cm^-3) and the YMW16 (www.xao.ac.cn/ymw16/) model (~ 33 pc cm^-3). The upper limit on the DM-inferred redshift is thus ~0.8. The S/N in the detection beam is 22, and an early estimate of the event’s fluence is ~ 60 +/- 15 Jy ms. The FRB’s estimated width (full width half power) is 26 ms.

Source localisation is excellent in the Right Ascension (~ 5 arcsec at 1-sigma) but poor in Declination (~1.2 deg at 1-sigma). The most likely position is RA = 21:29:50.61, DEC = -07:59:40.49, J2000, Galactic: Gl = 45.1°, Gb = -38.7°. The 95% confidence localisation arc is as follows:

21:29:50.50 -10:21:32.1
21:29:50.48 -09:52:40.9
21:29:50.49 -09:23:49.8
21:29:50.52 -08:54:58.6
21:29:50.56 -08:26:07.4
21:29:50.62 -07:57:16.2
21:29:50.63 -07:52:27.7
21:29:50.71 -07:23:36.5
21:29:50.81 -06:54:45.3
21:29:50.92 -06:25:54.1
21:29:51.06 -05:57:03.0
21:29:51.21 -05:28:11.8

A formula describing the localisation arc is:

RA = 21.500702 + 3.753954e-4*(DEC – 7.994579) + 1.053305e-5*(DEC – 7.994579)^2

Where RA is in hours, DEC is in deg, and is valid in the DEC range [-12.36,-3.63]

Follow-up observations of the FRB are encouraged.

 

Screen Shot 2017-10-20 at 10.13.50 AM

 

atelfrb5.localisationThe blue cross is the telescope pointing center; the green cross is the highest probability position of the FRB, and the line indicates the localisation arc.  Several low DM pulsars in the field of view are also seen in grey.