First detection of FRBs at the frequency 111 MHz at the radio telescope BSA LPI
ATel #11932; A. E. Rodin (PRAO ASC LPI), V. A. Fedorova (PRAO ASC LPI)
on 10 Aug 2018; 14:55 UT
Credential Certification: Alexander Rodin (rodin@prao.ru)
Subjects: Radio, Fast Radio Burst
Referred to by ATel #: 12899
Three new Fast Radio Burst were detected with the radio telescope BSA LPI of the Pushchino Radio Astronomy Observatory of the Lebedev Physical Institute (100 km south from Moscow) at the frequency 111 MHz during processing of archival data of scintillation of radio source on inhomogeneities of interplanetary plasma in period from 2012 to 2018.
The Radio telescope BSA LPI is meridian-type instrument (200m x 400m) with a central frequency of 111MHz and band width 2.5 MHz. The fluctuation sensitivity is 140 mJy at time resolution 0.1 s. In so doing the time interval between samples is 100 ms. The radio telescope has multibeam diagram consisting of 96 beams. This gives a possibility for continuous monitoring of large area of the sky (from -8.20 to +42.13 degrees by declination).
The main goal of data processing was to search for pulses from the repeated FRB 121102. The results are given below:
FRB 151018 (01:05:48 2015-10-18 UTC): the pulse has coordinates RA(J2000) = 05:21:00 and DEC(J2000) = +33:06:00. Dispersion measure is 570 pc/cm^3+/-5 pc/cm^3 (DM_Gal=275 pc/cm^3 in accordance with the YMW16 model). A signal-to-noise ratio S/N ~ 6.2. The peak flux density is ~ 1.4 Jy according to our estimates. Width of pulse is ~ 2.5 s.
FRB 160920 (03:05:43 2016-09-20 UTC): the pulse has coordinates RA(J2000) = 05:34:00 and DEC(J2000) = +41:45:00. Dispersion measure is 1767 pc/cm^3+/-4 pc/cm^3 (DM_Gal=250 pc/cm^3 in accordance with the YMW16 model). A signal-to-noise ratio S/N ~ 9.1. The peak flux density is ~ 0.22 Jy. Width of pulse is ~ 5 s.
FRB 170606 (10:03:27 2017-06-06 UTC): coordinates of pulse are RA(J2000)= 05:34:00 and DEC(J2000)= +41:45:00. Dispersion measure is 247 pc/cm^3+/-5 pc/cm^3. A signal-to-noise ratio S/N ~ 8.3. The peak flux density is ~ 0.54 Jy. Width of pulse is ~ 3.3 s.
Each pulse is visible only in one beam of multibeam diagram of BSA LPI. Since the width of the main lobe of the beam pattern of the BSA LPI radio telescope at half the level is ~ 30', these coordinates have comparable error.
The coordinates of FRB 151018 coincide with coordinates of the repeated FRB 121102 within the error. Therefore, we can say with a high probability that pulse of known FRB 121102 was detected for the first time at the frequency 111 MHz. From here we can draw a conclusion about the spectral index of the event FRB 121102. Based on our estimates at 111 MHz and earlier measurements at different frequencies the spectral index v ~ -0.6+/-0.4.