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e-CALLISTO FITS Analyzer: A Software Framework for CALLISTO Solar Radio Data

G. L. S. S. Liyanage, J. Adassuriya, K. P. S. C. Jayaratne, C. Monstein, P. K. Manoharan

Abstract

Solar radio bursts are important signatures of dynamic processes in the solar corona, including particle acceleration and shock propagation associated with solar flares and coronal mass ejections. Among the missions that report solar radio bursts within 24 hours, the e-CALLISTO archive is the largest, with more than 150 stations worldwide. The archive generates large volumes of FITS data that are often affected by radio-frequency interference and background noise. Irregular frequency setups in different stations are also a limitation of statistical analysis of SRBs. Each CALLISTO observation is a 15-minute frame, which often causes a single burst to split over multiple frames, making event-level analysis difficult. This work presents the e-CALLISTO FITS Analyzer, a unified, interactive, cross-platform application for processing and analyzing e-CALLISTO dynamic spectra on Windows, macOS, and Linux. The application supports time and frequency merging to produce a continuous spectrum, applies mean background subtraction with user-controlled threshold clipping, and isolates burst regions through an interactive polygon mask in the time-frequency plane. It also extracts the maximum-intensity backbone, allows interactive outlier removal, and performs power-law fitting to estimate drift rates and derive shock height and speed using the Newkirk model, including $n$-fold scaling. For a Type II burst observed by Arecibo Observatory on 2 March 2022, the analyzer yielded an average drift rate of $-0.0400 \pm 0.0003\, MHz/s$ and an average shock speed of $449 \pm 1\, km/s$ at a height of $1.715 \pm 0.002\, R_{\odot}$. The e-CALLISTO FITS Analyzer supports more reproducible, event-focused SRB analysis and improves access to physically meaningful measurements from e-CALLISTO FITS data.

e-CALLISTO FITS Analyzer: A Software Framework for CALLISTO Solar Radio Data

Abstract

Solar radio bursts are important signatures of dynamic processes in the solar corona, including particle acceleration and shock propagation associated with solar flares and coronal mass ejections. Among the missions that report solar radio bursts within 24 hours, the e-CALLISTO archive is the largest, with more than 150 stations worldwide. The archive generates large volumes of FITS data that are often affected by radio-frequency interference and background noise. Irregular frequency setups in different stations are also a limitation of statistical analysis of SRBs. Each CALLISTO observation is a 15-minute frame, which often causes a single burst to split over multiple frames, making event-level analysis difficult. This work presents the e-CALLISTO FITS Analyzer, a unified, interactive, cross-platform application for processing and analyzing e-CALLISTO dynamic spectra on Windows, macOS, and Linux. The application supports time and frequency merging to produce a continuous spectrum, applies mean background subtraction with user-controlled threshold clipping, and isolates burst regions through an interactive polygon mask in the time-frequency plane. It also extracts the maximum-intensity backbone, allows interactive outlier removal, and performs power-law fitting to estimate drift rates and derive shock height and speed using the Newkirk model, including -fold scaling. For a Type II burst observed by Arecibo Observatory on 2 March 2022, the analyzer yielded an average drift rate of and an average shock speed of at a height of . The e-CALLISTO FITS Analyzer supports more reproducible, event-focused SRB analysis and improves access to physically meaningful measurements from e-CALLISTO FITS data.

Paper Structure

This paper contains 20 sections, 17 equations, 5 figures, 1 table.

Table of Contents

  1. Introduction
  2. e-CALLISTO solar radio observations
  3. CALLISTO solar radio spectrometer
  4. Data from CALLISTO
  5. Software Implementation and Processing Workflow
  6. Data model and FITS handling
  7. Data acquisition and insertion
  8. FITS combination across time and frequency
  9. background subtraction and burst isolation
  10. Data visualization
  11. User interaction and control layer
  12. Extensibility and modular design
  13. Software dependencies and environment
  14. Design considerations and limitations
  15. Analysis of Type II bursts
  16. ...and 5 more sections

Figures (5)

  • Figure 1: Overall workflow of the e-Callisto FITS Analyzer.
  • Figure 2: Data acquisition workflow of the e-Callisto FITS Analyzer.
  • Figure 3: The FITS combination workflow for Time and Frequency merge.
  • Figure 4: The main application window showing a Type II solar radio burst observed at Arecibo Observatory on 2 March 2022 after background subtraction.
  • Figure 5: Processing stages of the e-CALLISTO FITS Analyzer for a Type II solar radio burst observed by CALLISTO at Arecibo Observatory on 02/03/2022: (a) raw dynamic spectrum, (b) background-subtracted dynamic spectrum, (c) isolated fundamental band, and (d) analyzer window showing the maximum-intensity backbone and derived shock parameters computed using the one-fold Newkirk electron density model.