Wednesday Colloquium



CAMK Conference



CAMK Conference


"The impact of the ionosphere on ground-based detection of the global Epoch of Reionisation"

Marcin Sokołowski (Curtin University, Perth, Australia)

The redshifted 21cm line of neutral hydrogen (HI), which can potentially be observed at low radio frequencies (~ 50-200 MHz), is a powerful probe of the physical conditions of the inter-galactic medium during Cosmic Dawn and the Epoch of Reionisation (EoR). The sky-averaged HI signal (global EoR) is expected to be extremely weak (of the order of 100 mK) in comparison to the foregrounds of up to 10000 K at the lowest frequencies. Moreover, the tiny signature of the EoR has to be identified amongst instrumental effects. Precision better than 10mK at 80 MHz requires tens of hours of integration with a highly calibrated system, however the overall accuracy can be affected by propagation effects in the ionosphere. BIGHORNS (Broadband Instrument for Global HydrOgen ReioNisation Signal) is a total power radiometer designed and build at Curtin University (Perth, Western Australia) to detect signature of the global Epoch of Reionisation in the-sky averaged spectrum. After several test deployments in remote, radio-quiet locations in Western Australia, in October 2014 the system with a conical log spiral antenna was permanently deployed at the Murchison Radio-astronomy Observatory (MRO), where it also monitors radio-frequency interference (RFI) at the future site of the low-frequency component of the Square Kilometre Array (SKA). I will present the BIGHORNS instrument and address the main challenges of the global EoR measurement. I will also present analysis of the 2014/2015 data collected at the MRO assessing the significance of the ionospheric effects on the ground-based detection of the global EoR signal. Finally, I will give a brief overview of some SKA-low activities in Western Australia.


"Highlights from the ongoing search for symbiotic stars in the Local Group of Galaxies"

Joanna Mikołajewska (NCAC, Warsaw)

I will present and discuss basic characteristics of the first symbiotic stars detected in M31 and M33 as well well as some serendipitous discoveries.