J/MNRAS/473/2965 Interplanetary scintillation at 79 and 158MHz (Morgan+, 2018) ================================================================================ Interplanetary Scintillation with the Murchison Widefield Array. I. a sub-arcsecond survey over 900 deg^2^ at 79 and 158 MHz. Morgan J.S., Macquart J.-P., Ekers R., Chhetri R., Tokumaru M., Manoharan P.K., Tremblay S., Bisi M.M., Jackson B.V. =2018MNRAS.473.2965M (SIMBAD/NED BibCode) ================================================================================ ADC_Keywords: Radio sources ; Galaxies, radio ; Interferometry Keywords: scattering - techniques: high angular resolution - techniques: image processing - techniques: interferometric - Sun: heliosphere - radio continuum: galaxies Abstract: We present the first dedicated observations of Interplanetary Scintillation (IPS) with the Murchison Widefield Array. We have developed a synthesis imaging technique, tailored to the properties of modern 'large-N' low-frequency radio telescopes. This allows us to image the variability on IPS time-scales across 900deg^2^ simultaneously. We show that for our observations, a sampling rate of just 2Hz is sufficient to resolve the IPS signature of most sources. We develop tests to ensure that IPS variability is separated from ionospheric or instrumental variability. We validate our results by comparison with existing catalogues of IPS sources, and near-contemporaneous observations by other IPS facilities. Using just 5 min of data, we produce catalogues at both 79 and 158MHz, each containing over 350 scintillating sources. At the field centre, we detect approximately one scintillating source per square degree, with a minimum scintillating flux density at 158MHz of 110mJy, corresponding to a compact flux density of approximately 400mJy. Each of these sources is a known radio source, however only a minority were previously known to contain sub-arcsecond components. We discuss our findings and the prospects they hold for future astrophysical and heliospheric studies. Description: In order to allow multifrequency Interplanetary Scintillation (IPS) analysis, it was decided to split the MWA's 30.72MHz of instantaneous bandwidth into two bands, spaced approximately a factor of two apart in frequency. Within the MWA observing band, there is 15MHz of bandwidth directly below the FM broadcast band centred on 79MHz. An observing frequency of 158MHz, double the lower band frequency, is close to the centre of the MWA's usable band and gives a good trade-off between sensitivity, angular resolution, and field of view. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table2.dat 191 377 High-band catalogue of scintillating sources table3.dat 242 353 Low-band catalogue of scintillating sources -------------------------------------------------------------------------------- See also: J/A+A/598/A78 : The GMRT 150MHz all-sky radio survey (Intema+, 2017) Byte-by-byte Description of file: table2.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 24 A24 --- Name1 Source name of best match, TGSSADR JHHMMSS.s+DDMMSS 26- 34 E9.5 deg RAdeg Right ascension (J2000.0) of best match 36- 43 F8.5 deg DEdeg Declination (J2000.0) of best match 45- 62 F18.16 --- pmatch1 Probability that best match is correct match 64- 87 A24 --- Name2 Source name of 2nd best match, TGSSADR JHHMMSS.s+DDMMSS 89-107 F19.17 --- pmatch2 Probability that 2nd best match is correct match 109-119 F11.8 Jy S TGSSADR flux density at 158MHz of best match 121-131 F11.9 Jy e_S rms uncertainty on S 133-150 F18.15 deg Elong Solar elongation on date of observation 152-170 F19.17 Jy dS Scintillating flux density measured 172-191 F20.18 Jy e_dS rms uncertainty on dS -------------------------------------------------------------------------------- Byte-by-byte Description of file: table3.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 24 A24 --- Name1 Source name of best match, TGSSADR JHHMMSS.s+DDMMSS 26- 34 F9.5 deg RAdeg Right ascension (J2000.0) of best match 36- 44 F9.5 deg DEdeg Declination (J2000.0) of best match 46- 64 F19.17 --- pmatch1 Probability that best match is correct match 66- 89 A24 --- Name2 Source name of 2nd best match, TGSSADR JHHMMSS.s+DDMMSS 91-109 F19.17 --- pmatch2 Probability that 2nd best match is correct match 111-134 A24 --- Name3 Source name of third best match best match, TGSSADR JHHMMSS.s+DDMMSS 136-154 F19.17 --- pmatch3 Probability that third best match best match 156-160 F5.2 Jy S VLSSr flux density at 78.7MHz of best match 162-180 F19.17 Jy e_S rms uncertainty on S 182-200 F19.16 deg Elong Solar elongation on date of observation 202-221 F20.17 Jy dS Scintillating flux density measured 223-242 F20.18 Jy e_dS rms uncertainty on dS -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 22-Nov-2020