PlanetMapper: A Python package for visualising, navigating and mapping Solar System observations

PlanetMapper is an open-source Python package to visualise, process and understand remote sensing observations of Solar System objects, such as planets, moons and rings (King & Fletcher, 2023). Astronomers can use PlanetMapper to 'navigate' observations by calculating coordinate values (such as latitude and longitude) for each pixel in an observed image and can map observations by projecting the observed data onto a map of the target body. Calculated values are exportable and directly accessible through a well-documented API, allowing PlanetMapper to be used for custom analysis and processing.

PlanetMapper can be used to help generate publication quality figures and is designed to integrate directly with the Matplotlib plotting library. For example, ‘wireframe’ plots of planetary bodies (Figure 1) can be generated with a single line of code, and can help to provide important spatial context for remote sensing observations. All plotted elements are fully customisable, allowing complex custom plots of observation geometries to be generated with ease.

PlanetMapper also has a Graphical User Interface (GUI) to significantly simplify the processing of astronomical data (Figure 2). Users can load an observation in the GUI, then interactively fit, navigate, map and save the obsevations, with no coding required.

PlanetMapper can be applied to a wide range of datasets, including both amateur and professional ground-based observations, and data from space telescopes like Hubble and JWST. It is built using the NAIF SPICE toolkit (Acton et al., 2018), so can be used for any target which has appropriate SPICE kernels available.

The package is fully documented and has a set of helpful user guides. It is automatically tested with both unit and integration tests and is published under the MIT open source license. PlanetMapper is distributed on PyPI and conda, and can easily be installed by running pip install planetmapper.

Links:

• Documentation: https://planetmapper.readthedocs.io
• GitHub: https://github.com/ortk95/planetmapper
• Paper: https://doi.org/10.21105/joss.05728

Figure 1: ‘Wireframe’ generated with PlanetMapper, visualising the appearance of Saturn from Earth on 1 January 2020. This plot was created with a single function call,  and all elements are fully customisable.

Figure 2: Screenshot of the PlanetMapper Graphical User Interface (GUI)  being used to fit a ground-based VLT observation of Europa (King et al., 2022). The user can adjust the location of the fitted disc (the white circle) until it matches the observed data. Any embedded WCS information (containing approximate telescope pointing) is used to initialise the position, size and rotation of the disc, so often only small manual adjustments are needed to correct telescope pointing errors.

Figure 3: More complex example of PlanetMapper’s functionality. The observation of Jupiter (top left) was navigated and mapped (top right) using PlanetMapper. Emission angle backplanes generated with PlanetMapper are shown in the bottom panels. Jupiter image credit: NASA, ESA, STScI, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley) and the OPAL team.