What is APIS ?

In brief

Planetary aurorae are powerful emissions radiated from the auroral regions of magnetized planets by accelerated charged particles, in a wide range of wavelengths, from radio to X-rays. The UV range in particular is adapted to measure collisionally excited transitions of H and H2, which are the prominent species in the upper atmosphere of the giant planets, produced by precipitating auroral particles. It additionally benefits a good angular resolution. Auroral UV observations therefore provide a wealth of informations on planetary atmospheres and magnetospheres. They also offer a unique diagnostic to remotely probe the solar wind activity throughout the heliosphere.

Among the space-based UV observatories, the ESA/NASA Hubble Space Telescope (HST) intensively observed the outer planetary systems (Jupiter, Saturn, Uranus) in the Far-UV (FUV) from 1993 up to now, providing thousands of images and spectra, often in the frame of combined observations with spacecraft dedicated to planetary exploration (Galileo orbiting Jupiter over 1995-2003, Cassini flyby of Jupiter in 2000, Cassini orbiting Saturn over 2004-2017, New Horizons flyby of Jupiter in 2007, Juno in orbit around Jupiter since 2017). The Cassini/UVIS spectro-imager for instance probed Saturn (and Jupiter during the cruise phase) auroral emissions through its Extreme UV (EUV) and FUV channels. Another Earth-based UV observatory is the JAXA Hisaki satellite which monitors solar system bodies on the long-term with spectro-imaging data in the EUV and FUV ranges since 2013. UV observations have also been carried in situ from spectro-imagers onboard the above-mentioned satellites. These observations now form rich databases, of interest for a a wide community, whose use remains limited by the difficulty to access and use them.

The Auroral Planetary Imaging and Spectroscopy (APIS) service aims at providing a free and simple access to processed, high-level, auroral data.

Three complementary databases can be queried by the APIS search interface to date. They are detailed here and summarized below :
- The primary database was released together with the APIS service in 2012. It is built from the STSci archive of public HST planetary and moon auroral observations using the STIS and ACS spectro-imagers. It is fully described here.
- In 2017-2018, we developed the possibility to query external databases such as the Hisaki/EXCEED set of observations, which is described here.
- More recently, we developed a full Cassini/UVIS Saturn auroral database from the PDS public archive, which was released mid-2019.

The data accessible through APIS can then be used interactively by tools of the Virtual Observatory (VO) community or inter-connected with other VO services, such as those of the french Center of Plasma Physics (CDPP).

Forfuitously, the bull APIS is also the ancient egyptian god of fertilization, wearing an active solar disc between the horns.


The APIS service is developed at LESIA, Observatoire de Paris, CNRS. The database is archived and maintained at Paris Astronomical Data Centre.

L. Lamy Assistant astronomer LESIA-Observatoire de Paris Scientific responsible
R. Prangé Research Director LESIA-Observatoire de Paris Scientific expertise
F. Henry Research engineer LESIA-Observatoire de Paris Project manager
R. Romagnan Research engineer LESIA-Observatoire de Paris Query of external VO databases
B. Cecconi Assistant astronomer LESIA-Observatoire de Paris VO interoperability, VESPA and MASER services
P. Le Sidaner Research engineer VO-Paris Data Centre Archiving, head of Paris Astronomical Data Centre
N. Moreau Temporary study engineer LERMA-Observatoire de Paris Specview, contact VAMDC
A. Shih Research engineer VO-Paris Data Centre Responsible of Paris Astronomical Data Centre infrastructure
C. Chauvin Temporary study engineer Paris Astronomical Data Centre Interoperability, EPN-TAP client
S. Cnudde Study engineer LESIA-Observatoire de Paris Graphical design (SIGAL service)
Former contributors Postdocs/CDDs LESIA-Observatoire de Paris F. Magalhaes, L. Debisschop
Former contributors Students LESIA-Observatoire de Paris N. Carrier, L. Gosset, C. Louis, C. Berland, D. Afgoun, R. Desmonts


The APIS service makes use of planetary ephemeris provided by the Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE) through its VO service MIRIADE (piloted by J. Berthier, IMCCE, Observatoire de Paris) and by the University of Iowa through a dedicated ephemeris tool (piloted by J. Green).

Hisaki/EXCEED data are processed by, and under the responsability of, japanese colleagues (T. Kimura et al., RIKEN, Japan).

The APIS data can be used interactively with VO plotting tools such as Aladin (developed at CDS, Strabourg), Cassis (developed by J.-M. Glorian et al. at IRAP, Toulouse) or Specview (maintained by I. Busco at STSci, Baltimore).

The APIS service is developed along VO standards (such efforts benefit regular discussions with experts such as S. Erard, J. Aboudarham, LESIA and C. Marmo, GEOPS) and is therefore inter-connected with VO services of the CDPP such as the AMDA, 3Dview and propagation tools (V. Génot, N. André, A. Rouillard, IRAP) .