Determining trajectories of solar transients such as coronal mass ejections is not always easy. White light images from SECCHI’s (Sun Earth Connection Coronal and Heliospheric Investigation) heliospheric imagers are difficult to interpret because they represent a lineof- sight projection of optically thin solar wind structures. A structure’s image by itself gives no information about its angle of propagation relative to the Sunspacecraft line, and an image may show a superposition of several structures, all propagating at different angles. Analyzing SECCHI heliospheric imager data using plots of elongation (angle from the Sun) versus time at fixed position angle (aka “Jplots”) has proved extremely useful in understanding the observed solar wind structures. This technique has been used to study CME (coronal mass ejection) propagation, CIRs (corotating interaction regions), and blobs.
SATPLOT software was developed to create and analyze such elongation versus time plots. The tool uses a library of cylindrical maps of the data for each spacecraft’s panoramic field-of-view. Each map includes data from three SECCHI white-light telescopes (the COR2 coronagraph and both heliospheric imagers) at one time for one spacecraft. The maps are created using a Plate Carree projection, optimized for creating the elongation versus time plots. The tool can be used to analyze the observed tracks of features seen in the maps, and the tracks are then used to extract information, for example, on the angle of propagation of the feature.
This work was done by Jeffrey R. Hall and Paulett C. Liewer of Caltech for NASA’s Jet Propulsion Laboratory.
This software is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
SATPLOT for Analysis of SECCHI Heliospheric Imager Data
(reference NPO-47826) is currently available for download from the TSP library.
Don't have an account?
Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) detailing the SATPLOT software tool, designed for the analysis of data from the SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) Heliospheric Imagers. The primary focus of SATPLOT is to facilitate the interpretation of white light images of solar wind structures, which are often complex due to their line-of-sight projection characteristics.
The document outlines the challenges in interpreting these images, as they may represent multiple solar wind structures propagating at different angles. To address this, SATPLOT employs a technique that generates elongation versus time plots, also known as "Jplots." These plots are instrumental in understanding the dynamics of solar phenomena, such as coronal mass ejections (CMEs) and corotating interaction regions (CIRs). The software utilizes cylindrical maps of data from three SECCHI white-light telescopes, including the COR2 coronagraph and both heliospheric imagers, to create these visualizations.
The document provides user instructions for utilizing SATPLOT effectively. Users are guided through a series of steps, starting from downloading pre-computed cylindrical maps to generating Jplots and analyzing the trajectories of solar features. The instructions include specific commands for the IDL (Interactive Data Language) environment, allowing users to preview events, create time series displays, and export data for further analysis.
Additionally, the document emphasizes the importance of the SATPLOT tool in enhancing the understanding of solar wind structures and their propagation beyond the coronagraph's field of view. It highlights the collaborative efforts of researchers from JPL, the Naval Research Laboratory (NRL), and NASA's Goddard Space Flight Center (GSFC) in developing this tool.
Overall, the Technical Support Package serves as a comprehensive guide for researchers and users interested in solar physics, providing them with the necessary tools and methodologies to analyze heliospheric imager data effectively. It underscores the significance of SATPLOT in advancing the study of solar phenomena and its potential applications in both scientific research and technological development.
