Title:	A multi-site study of radio environment for cosmology experiments
Authors:	Agrawal, Yash Singh, Saurabh Girish, B S Somashekar, R Srivani, K S Raghunathan, A Pandharpure, Vishakha S Shankar, Udaya N Keerthipriya, S Rao, Mayuri Sathyanarayana
Keywords:	Astronomical Instrumentation Observational Cosmology Reionization First stars
Issue Date:	29-Oct-2025
Publisher:	Experimental Astronomy
Citation:	Experimental Astronomy, 2025, Vol. 60, AR No.22
Abstract:	Radio Frequency Interference (RFI) presents a significant challenge for carrying out precision measurements in radio astronomy. In particular, RFI can be a showstopper when looking for faint cosmological signals such as the red-shifted 21-cm line from cosmic dawn (CD) and epoch of reionization (EoR). As wireless communications, satellite transmissions, and other RF technologies proliferate globally, understanding the RFI landscape has become essential for site selection and data integrity. We present findings from RFI surveys conducted at four distinct locations: three locations in India, the Gauribidanur Radio Observatory in Karnataka, Twin Lakes in Ladakh, Kalpong Dam in the Andaman Islands, and the Gruvebadet Atmosphere Laboratory in Ny-Ålesund, Svalbard, Norway. These sites, selected based on their geographical diversity and varying levels of human activity, were studied to assess RFI presence in 30-300 MHz bands, critical for low-frequency observations and experiments targeting the 21-cm CD/EoR signal. Using an automated RFI detection approach via the Hampel filter and singular value decomposition, the surveys identified both persistent and transient interference, which varies with location and time. The results provide a comprehensive view of the RFI environment at each site, informing the feasibility of long-term cosmological observations and aiding in the mitigation of RFI in radio astronomical data. The methods developed to characterize RFI can be easily generalized to any location and experiment.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/8663
ISSN:	1572-9508
Alternative Location:	https://doi.org/10.48550/arXiv.2504.09125 https://doi.org/10.1007/s10686-025-10036-6
Copyright:	2025 The Author(s
Appears in Collections:	Research Papers (A&A)

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