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Multi-messenger observations of a Binary Neutron Star Merger

See Abbott, B.P., Abbott, R., et al. 2017, ApJL, 848, L12

The authors present multi-wavelength scatter broadening observations of 47 pulsars, made with the Giant Metre-wave Radio Telescope (GMRT), Ooty Radio Telescope (ORT) and Long Wavelength Array (LWA). The GMRT observations have been made in the phased array mode at 148, 234, and 610 MHz and the ORT observations at 327 MHz. The LWA data sets have been obtained from the LWA pulsar data archive. The broadening of each pulsar as a function of observing frequency provides the frequency scaling index, α

Design and characterization of the Large-Aperture Experiment to Detect the Dark Age (LEDA) radiometer systems

D.C. Price et al. MNRAS (2017) Preprint October 11, 2017

Measurement of the 21-cm emission from the early Universe via radiometric methods requires exquisite calibration and comprehensive knowledge of the radiometer systems. Measurement of the cosmological 21-cm signal over the 40 − 85 MHz band could constrain models of star formation and reionization during Cosmic Dawn. In this paper, we have presented the design and characteristics of the LEDA radiometer systems. Comparison of the system performance with predictions based on the GSM2008 sky model and LWA antenna gain pattern are in agreement to the 15% level over 40 − 83 MHz. Between antennas, data agree to ±5%. Above 83 MHz, the rolloff of the filter for FM-band rejection (88 − 108 MHz) becomes significant. Further characterization work is required before meaningful limits may be placed on 21-cm emission during cosmic dawn. In particular, individual characterization of the antenna’s direction-dependent gain is required to account for the frequency dependence of the beam. Work on this characterization is underway, using interferometric measurements with the combined LEDA radiometer antennas and OVRO-LWA core antennas.