An integrated system at the Bleien Observatory for mapping the Galaxy

Abstract

We describe the design and performance of the hardware system at the Bleien Observatory. The system is designed to deliver a map of the Galaxy for studying the foreground contamination of low-redshift (z=0.13-0.43) H I intensity mapping experiments as well as other astronomical Galactic studies. This hardware system is composed of a 7m parabolic dish, a dual-polarization corrugated horn feed, a pseudo correlation receiver, a Fast Fourier Transform spectrometer, and an integrated control system that controls and monitors the progress of the data collection. The main innovative designs in the hardware are (1) the pseudo correlation receiver and the cold reference source within (2) the high dynamic range, high frequency resolution spectrometer and (3) the phase-switch implementation of the system. This is the first time these technologies are used together for a L-band radio telescope to achieve an electronically stable system, which is an essential first step for wide-field cosmological measurements. This work demonstrates the prospects and challenges for future H I intensity mapping experiments.

Radio frequency interference mitigation using deep convolutional neural networks

“…The amplitude and the rate of the burst is randomly sampled such that the expected data loss of the observation site is matched. [18,2]. We have access to the perfect ground truth of this simulated data since we know for each pixel if it has been perturbed by simulated RFI.…”

“…We train the parameters of the U-Net using the early Science Verification data acquired at the Bleien Observatory [2]. This data set was collected using a 7m single-dish telescope operating in drift-scan mode with a frequency range of 990 -1260 MHz.…”

“…In particular, observations of the 21 cm neutral hydrogen line allows us to probe the high-redshift Universe, which is not easily accessible with other wavelengths [1]. In addition, radio band data provides important information for foreground studies of cosmic microwave background, and also Galactic astronomy [2]. Ongoing and future experiments such as LOFAR [3], GMRT [4], PAPER [5], CHIME [6], BINGO [7,8], HERA [9], Tianlai [10], and the SKA [11] aim to carry out wide-field surveys in the radio band that cover large portions of the sky.…”

Dark Energy Survey Year 1 results: the impact of galaxy neighbours on weak lensing cosmology with im3shape

“…This paper is intended as a companion study to Zuntz et al (2017) (Z17), where we present two shear catalogues derived from DES Y1 dataset. It is also presented alongside a raft of other papers, which use both catalogues and show them to be consistent in a number of different scientific contexts (Troxel et al 2017;Prat et al 2017;Chang et al 2017;DES Collaboration et al 2017) Containing 22 million and 35 million galaxies respectively, these catalogues are the product of two independent maximum likelihood codes. The first, called IM3SHAPE, implements simultaneous fits using multiple models and we calibrate externally using simulations.…”

Baryon Acoustic Oscillations from Integrated Neutral Gas Observations: Radio Frequency Interference Measurements and Telescope Site Selection

“…Six filters were required to remove mobile signals, including a steep notch filter below ∼980 MHz. Full details of the system are in Chang et al (2017). Although the site has a protection radius of 1.5 km, this only covers nearby terrestrial sources like mobile phone, TV-or radio-transmitters, and aircraft and satellite signals are not included.…”