Heliograph of the UTR-2 Radio Telescope

TL;DR

This paper describes a broadband analog-digital heliograph based on the UTR-2 radio telescope, capable of real-time solar corona imaging with high resolution and dynamic range across 8-32 MHz frequencies.

Contribution

It introduces a novel digital heliograph system with a phase shift module for fast sky scanning and real-time image formation, enhancing solar radio observations.

Findings

Achieved high-resolution solar corona images at 8-32 MHz.

Demonstrated real-time imaging with 1 ms time resolution.

Provided detailed design and operation of the phase shifter and digital spectrum processor.

Abstract

The broadband analog-digital heliograph based on the UTR-2 radio telescope is described in detail. This device operates by employing the parallel-series principle when five equi-spaced array pattern beams which scan the given radio source (e.g. solar corona) are simultaneously shaped. As a result, the obtained image presents a frame of 5 x 8 pixels with the space resolution 25' x 25' at 25 MHz. Each pixel corresponds to the signal from the appropriate pattern beam. The most essential heliograph component is its phase shift module for fast sky scanning by pencil-shape antenna beams. Its design, as well as its switched cable lengths calculation procedure, are presented, too. Each heliogram is formed in the actual heliograph just by using this phase shifter. Every pixel of a signal received from the corresponding antenna pattern beam is the cross-correlation dynamic spectrum (time-frequency-intensity) measured in real time with the digital spectrum processor. This new generation heliograph gives the solar corona images in the frequency range 8-32 MHz with the frequency resolution 4 kHz, time resolution to 1 ms, and dynamic range about 90 dB. The heliographic observations of radio sources and solar corona made in summer of 2010 are demonstrated as examples.