Characteristics Analysis of Type II Solar Radio Bursts Detected by CALLISTO Spectrometer at The Space Technology Complex (STC), Banting, Malaysia During Ascending Phase of Solar Cycle 25

Abstract

Within the meter wavelength region, Type II Solar Radio Bursts (SRBs) have been determined to be some of the most significant solar radio emission events.  They are produced by magnetohydrodynamic (MHD) shocks generated by solar flares or Coronal Mass Ejections (CMEs). This paper presents an analysis of the characteristics of Type II SRBs detected by the CALLISTO (Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory) station at the Space Technology Complex (STC), Banting, managed by the Malaysian Space Agency (MYSA).  In this paper, a total of 21 type II SRBs were observed at the station, during the period of 1 October 2021 to 29 February 2024, based on data from the e-CALLISTO website. The characteristics of these SRBs were thoroughly analysed to gain insights into their properties. The analysis focused on their association with flare event classes and CME parameters categorized by linear speed and angular width. Additionally, the study examined the occurrence of Herringbone or harmonic structures and drift rates during the solar cycle 25’s ascending phase. Data on solar flares were obtained from the Geostationary Operational Environmental Satellites (GOES), while CMEs were obtained from the Large Angle Spectroscopy Coronagraph Observatory (LASCO). Based on the present study, it is found that 20 out of 21 type II SRBs are connected with both solar flares and CMEs. Among these, 18 out of 21 type II SRBs were connected with intense GOES X-rays flares.  Furthermore, 45% of the type II SRBs were related to fast and wide CMEs, whereas only 20% of the type II SRBs were linked with slow and narrow CMEs.  Additionally, partial and full halo CMEs were observed in conjunction with half of the detected type II SRBs.  The study also identified the drift rate and duration of type II SRBs, varying between 0.08 to 1.56 MHzs⁻¹ and ~ 1 to 5 minutes, respectively.  Among them, 62% exhibited harmonic structures, and the rest, 38% showed herringbone structures.