In this thread we will present the global cylindrical maps of Jupiter produced at each perijove from the JunoCam images, up to PJ48.
They are composite RGB maps in equirectangular projection using planetocentric latitudes, usually at 10 pixels/degree and with L3=0 at the centre. Latitude and longitude (L3) scales have been added to most maps. Formats were variable at the early perijoves.
The raw images were processed and map-projected by Gerald Eichstädt, then the single-image maps were composited by John Rogers in Adobe Photoshop, except for some of the later perijoves when G.E. experimented with an automatic assembly technique. There are two exceptions (PJ22 & PJ29) when we present maps by Brian Swift instead, having been posted on the JunoCam web site.
At the first few perijoves the close-up images were not included in the maps, and the longitude orientation was approximate (± 1-2°), as we deduced it by alignment with ground-based observations before accurate navigation was established. There are still small uncertainties in navigation so positions may be uncertain by a few pixels. Intensities and colour balance are arbitrary, and have been adjusted to reduce visible seams between images and to enhance regional contrast. Therefore, any broad diffuse features should not be relied on without consulting the original single-image maps. Adjustment of colour balance was especially necessary in 2021-22 as the original images became progressively redder, apparently due to radiation-induced reddening of the camera optics. Recently, G.E. has applied a correction for this. Nevertheless, there are still noticeable differences in intensities and colour balance between different maps.
The global coverage has varied during six years of the mission due to the evolution of Juno’s orbit. At the early and the most recent perijoves, when the sub-spacecraft track was not far from the terminator, Juno was usually oriented so that JunoCam obtained extensive inbound coverage of the northern hemisphere and outbound coverage of the southern hemisphere. In the intervening years, pointing constraints meant that less of the northern hemisphere was imaged. There were no images at PJ2, and none of the northern hemisphere at PJ19 and PJ48.
The maps are in JPEG format in the ZIP files attached to this and subsequent Comments. (TIF files are available if needed.) For some perijoves, an additional, labelled copy of the map is included, as posted in JHR’s perijove reports. These can be found on this web site and on the JunoCam web site (https://www.missionjuno.swri.edu/junocam/think-tank).
The maps are provided under a CC-BY licence: “The CC BY licence allows anyone to: copy, distribute and transmit work; adapt work; make commercial use of the work under the condition that the user must attribute the work in the manner specified by the author or licensor (but not in any way that suggests they endorse the user or their use of the work).” I.e. these maps are in the public domain but should always be credited as indicated (NASA / JPL / SwRI / MSSS / Gerald Eichstädt / John Rogers); and we ask that anyone wishing to use them for research or commercial purposes would contact us first.
–John Rogers (2023 Feb.16).
- JunoCam-global-maps_PJ1-PJ12.zip [28.69 MB]