Jupiter low frequency radio emissions have been studied since their discovery (Burke and Franklin, 1955), with ground (from 10 to 40 MHz) and space observatories (down to a few kHz), the ground based observations being limited by the ionospheric cutoff at ∼10 MHz. The Jovian radio spectrum displays several components, which can be identified in dynamic spectra (time series of spectra), thanks to their temporal-spectral arc-shaped characteristic features (see, e.g.: Zarka, 2000; 2007). Moreover, a subset of Jovian radio components are driven by the interaction between the Jovian magnetic field and the Galilean moons, specifically with the moon Io (Bigg, 1963), but also with Europa and Ganymede (Louis et al., 2017a; Zarka et al., 2018a). The arc-shaped temporal-spectral geometry is a consequence of the radio emission mechanism, which produces a strongly anisotropic beaming pattern. Hence the observer’s location is a key parameter for prediction the observability of Jovian radio emissions. Jupiter observation probability maps have been produced with the first published catalogues (see e.g.: Bigg, 1963; Leblanc et al., 1981), relating the observer’s longitude in the Jovian System III frame (Higgins et al., 1997) and the phase of Io.

Planning or analysing Jupiter radio observations thus requires to know the observation geometry: observation date, observer’s location and phase of the Jovian moons. In this article, we present an online application providing the probability of observing Jovian radio components depending on the observation and Jovian system geometries.

The first use case is the analysis of a Jupiter low frequency radio observation. As presented in the introduction section, the interpretation of Jupiter radio emission observations requires an detailed knowledge of the geometry of the Jovian system, together with the observer’s location. The observation configuration shall be displayed in a two-dimensional diagram with axes being (a) the longitude of the observer (usually in Jupiter system III longitude) also known as “Central Meridian Longitude” (or CML), and (b) the selected Moon phase with respect to the observer. Such a diagram is referred to as a “Phase-CML” map. Many Phase-CML maps have been published (see, e.g., Leblanc et al., 1981; Marques et al., 2017; Zarka et al., 2018a). Comparing the selected observation configuration with Phase-CML maps greatly facilitates the Jupiter decametric radio emission observation interpretation. A second critical aspect of the Jovian radio emissions is their shape in the temporal-spectral domain. Comparing the observed shape with predicted ones would also strengthen the scientific interpretation (see, e.g., Louis et al., 2017b).

The second use case is the preparation of a Jupiter low frequency radio observation. The same geometry configuration display against Phase-CML maps allows to select observation times with higher probability of detecting the studied radio component. Furthermore, in order to prepare a ground based observation, the knowledge of Jupiter’s elevation as seen from the observer’s location is also required.

A series of design requirements has been derived from the two use cases.

• Time range: The observation time (or time range) shall be configurable.

We have identified a set of existing tools serving the identified needs (observation planning and observation interpretation).

The “Jupiter Probability Tool” application has been designed following the requirements presented in Section 2. The tools cited in Section 3 are already implementing part of project requirements. Hence, our application’s graphical user interface implements some interface features found in existing tools (e.g., the location of Jupiter on the Phase-CML map, similarly to the Radio Jupiter Pro tool, as shown in Figure 2). However, since the previous tools are not open source, none of their code have been reused.

The application is using the SPICE kernel system (Acton et al., 2018) for computing observational and planetary ephemerides. It also displays contextual data, when available, such as observational data (e.g., from the NDA database) and pre-computed modeled data from the ExPRES modeling tool.

The application has been developed as a joint project between the MASER (Measuring, Analysing and Modeling of Emissions in the Radio range) service (Cecconi et al., 2020), and the NDA team (Lamy et al., 2017), with support of PADC (Paris Astronomical Data Centre).

The Jupiter Probability Tool application is a science ready tool for preparing and analysing Jupiter radio observations. It has already been used in several studies. Louis et al. (2021) prepared a series of joint Jupiter decametric observations on three international LOFAR stations (Ireland, France and Germany) using the Jupiter Probability Tool. Lamy et al. (2022a) is a comment on a published paper. The authors made use of the application to support their argumentation. Lamy et al. (2022b) also made use of the application to confirm that the observed emissions were Io-controlled emissions.

A series of improvement and new features are planned for the next versions of the application. Firstly, new observatories shall be implemented, especially space missions with low frequency radio instrumentation, such as, e.g., Cassini; STEREO-A; STEREO-B; WIND; Galileo; JUICE; Voyager 1; Voyager 2; and Mars Express. Improvement of the application to adhere to the FAIR (Findable, Accessible, Interoperable, and Reusable) principles (Wilkinson et al., 2016) are also in preparation. One of the planned feature in this context is the addition of provenance (Servillat et al., 2022) information to the output figures (with the provision of the list of citations to be used if the figures are included in a scientific publication), thus improving the reusability of the application products.