APIS - Auroral Planetary Imaging and Spectroscopy

APIS/HST data collection

Laurent LAMY — 2019-06-02T18:27:04Z

APIS/HST data collection

The APIS primary database consists of an internal base of HST FUV planetary auroral observations acquired by the STIS, ACS/SBC (and WFPC2) instruments since 1997. These include >12500 individual images and spectra, obtained with different instrumental configurations (filters, slits, gratings), for each of which is derived a set of higher level data.

Reference :

Title : APIS/HST data collection (2021)
Abstract : The APIS/HST data collection is composed of 3 data levels built from original omages and spectra of solar systems planets and satellites acquired by the Hubble Space Telescope (HST) in the Far-Ultraviolet range (100-180 nm) since 1997 (Lamy et al., Astronomy & Computing, 2015).
DOI : https://doi.org/10.25935/T184-3B87
Publisher : PADC, Observatoire de Paris
License : CC-BY 4.0
Citation : Lamy, L., & Henry, F. (2021). APIS/HST data collection (Version 1.0). PADC. https://doi.org/10.25935/T184-3B87

Imaging :

Images are displayed under three levels of data :
– original data (level 1) : images retrieved from the STSci archive and individually re-calibrated with the most recent calibration files. These "raw" observations are displayed as fits files and jpeg plots, built in the original telescope field-of-view with instrumental units and a linear intensity scale.
– processed data (level 2) : extracted, rotated and re-centered images displayed in the telescope field-of-view, in a planet-related frame. They are displayed as fits files and pdf, jpeg plots, built with instrumental units and a logarithmic intensity scale. The fits files contain 7 extensions including : the re-centered science image in instrumental units (extension 0), and the associated pixel planetocentric coordinates (extensions 1 to 6 : latitude, local time, zenithal solar angle and zenithal observing angle at the limb altitude, latitude and local time at the auroral peak altitude). Their header contains basic informations on the original observation and valued-added informations such as planetary and relevant spacecraft (Cassini/Galileo) ephemeris (source : IMCCE).
– Projections (level 3) :
— cylindrical projections provided in pdf and jpeg plots, built with physical units and a logarithmic intensity scale. The projections were applied to re-centered images, once a numerical model of background subtracted, and then converted into brightness units (see the note below) with a dedicated projection routine preserving the photon flux of a given emitting surface.
— polar projections provided in pdf and jpeg plots, built as cylindrical projections.

Spectroscopy :

Spectra are displayed under three levels of data :
– original data (level 1) : first order long-slit (or slitless) STIS 2D spectra retrieved from the STSci archive and individually re-calibrated with the most recent calibration files. They are displayed as fits files and jpeg plots, built in the original HST field-of-view (slit along the y axis, wavelengths along the x axis) with physical units and a linear intensity scale.
– processed data (level 2) : extracted 2D spectra, including a specific wavelength calibration whenever possible when not provided by STSci. They are displayed as fits files and pdf, jpeg plots, built in the original HST field-of-view with physical units and a linear intensity scale.
With respect to the above mentioned paper, a supplementary processing was applied jpeg/pdf plots of small targets (i.e. out of Jupiter/Saturn) : a median spectrum was subtracted to each row of the 2D spectrum, intensities <150nm were divided by 10 in order to facilitate comparison with signal >150nm and a white arrow at the top right now indicates the body northern pole. The fits files only contain the extracted 2D spectrum. Their header contains basic informations on the original observation and valued-added informations such as planetary and relevant spacecraft (Cassini/Galileo) ephemeris (source : IMCCE).
– 1D spectra (level 3) : 1D spectra extracted from level 2 data (not available for slitless observations). Three average 1D spectra were derived from intensity occurrence levels. They are displayed as fits files and pdf, jpeg plots, built with physical units and a linear intensity scale. The header of fits files contain informations similar to those of level 2.

Notes and caveats :

Needs for a specific data processing :

For some purposes concerning a limited set of observations, several improvements of the standard systematic data processing pipeline can be performed on demand :
– A semi-automatic fitting routine was systematically applied to retrieve the planet's exact position and pixel coordinates. Afterwards, a numerical background was subtracted to re-centered images before to proceed to cylindrical and to polar projections. More accurate centering and/or background models can be built case by case.
– STIS observations with long exposure times were most of the time acquired with the time-tag mode (see the detailed informations given by the search interface). This mode records the arrival time of each photon and provides the possibility to build sub-exposures over chosen intervals.
Example : Long exposure time-tagged images of Jupiter acquired in 2009 were sequenced in 21x100s long images each.
– In a near future, APIS aims at providing the total radiated and precipitated hemispheric power for each image. Such estimates can already be done on restricted regions of interest (cusps, spots).
– 1D spectra were built from simple occurrence levels applied to the original 2D spectrum. 1D spectra of specific features (auroral arcs, satellite spots/wakes etc.) can be derived case by case.

The case of Saturn and Jupiter :

The header of Saturn and Jupiter (and their moons) processed fits files contains supplementary informations as :
– Saturn's southern and northern SKR phases (source : Lamy, PRE7, 2011), available online.
– the position of main moons and the ephemeris of the Cassini and Galileo spacecraft (source : University of Iowa, Observatoire de Meudon).

The projections of Saturn's images display additional specific features : white boxes in cylindrical projections indicate the expected footprint of Enceladus, and dashed-dotted (dashed) lines in polar projections indicate southern (northern) reference rotating meridians derived from the southern (northern) SKR phase system.

The projections of Jupiter's images display markers at the footprint of the 4 galilean satellites : the arrows with decreasing thickness/length and increasing gray tone respectively indicate the footprint of Io, Europa, Ganymede and Callisto. These footprints have been modelled with the ISAaC - In-Situ and Auroral Contraints - magnetic field model (update of VIPAL, improved with the fitting of the Ganymede footprint, Hess, private communication). Supplementary magnetic boundaries of interest, such as the footprints of flux tubes crossing a constant distance at the equator, can be added on demand.

Imaging units :

We chose to display projected images in brightnesses (kilo-rayleighs, or kR) of total H2 emission over 80-170nm. Many past studies (e.g. Gérard et al., 2004, 2005, 2006 ; Grodent et al., 2001, 2003, 2005 ; Clarke et al., 2005, 2009 ; Lamy, 2008 ; Bonfond, 2010) have performed successive photometric calibrations of STIS and ACS/SBC with typical auroral spectra to convert instrumental units (counts/s) into physical brigthnesses. The derived obtained conversion factors yielded significant disparities, owing to the considered radiative species (H2 and/or H-Lya), the consideration of absorption by hydrocarbons and the selected bandpass (spectral domain of H2 emission, FUV domain or bandpass restricted to that of HST imaging filters), as discussed by (Gustin et al., 2012 et Lamy et al., 2013). Here, we used the most recent estimates of (Gustin et al., 2012) derived for the two broad filters of each instrument (with color ratios of 2.5, 1.1 and 1.04 for Jupiter, Saturn and Uranus respectively), that we completed for the other employed filters. The conversion factors of filters concerning wavelengths mainly beyond the spectrum of H2, as F165LP for ACS, were set to 0.

The case of moons :

Although fitted with ellipsoids as for the images of planets (the pixel coordinates are available within the fits files of processed data), the images of moons were neither projected nor converted into auroral kR, owing to the lack of reliable conversion factors.

STIS irregular dark current :

Recent STIS observations may suffer a significant dark current on the FUV-MAMA detector that varies unpredictably in intensity. This results in an extended glow contaminating in particular the top left quadrant of the MAMA detector. No specific processing is applied to account for this sporadic dark current (source : STSci STIS handbook).

APIS/Cassini/UVIS data collection

Laurent LAMY — 2019-06-02T18:25:27Z

APIS/Cassini/UVIS data collection

The APIS service queries an internal internal base of Cassini/UVIS FUV auroral observations of Saturn, made of 8000 individual slewing of both the northern and southern auroral regions obtained between 2004 and 2017.

Reference :

Title : APIS/Cassini/UVIS data collection (2021)
Abstract : The APIS/Cassini/UVIS data collection has been built from original Cassini/UVIS spectro-imaging auroral observations of Saturn in the Extreme- and Far-Ultraviolet range (80-180 nm) throughout the full Cassini orbital tour of Saturn between 2004 and 2017. The original data have been splitted into individual sweeps of Saturn's auroral regions and enriched with specific data processing and metadata. Details on the creation of this data collection can be found in (Magalhaes et al., AGU fall meeting, 2019).
DOI : https://doi.org/10.25935/WZ47-TM17
Publisher : PADC, Observatoire de Paris
License : CC-BY 4.0
Citation : Lamy, L., Magalhaes, F., & Henry, F. (2021). APIS/Cassini/UVIS data collection (Version 1.0). PADC. https://doi.org/10.25935/WZ47-TM17

Data format:

The data are provided as datacubes, with 2 spatial dimensions (along and across the slit) and a spectral one. UVIS regularly slew the auroral regions to provide pseudo-images of Saturn's aurorae.

The first derived data level (level 2) correspond to fits files of datacubes retrieved from the PDS archive, calibrated (in kR/A) and extracted as individual UVIS slewing. The quicklooks are displayed with a linear intensity scale.

An exhaustive internal report (Magalahes et al.) describing this processing pipeline will be accessible soon.

Hisaki database

Laurent LAMY — 2019-06-02T18:24:09Z

Hisaki database

Since 2017, the APIS search interface also queries external Hisaki EUV spectro-imaging observations of solar system planets acquired with the EXCEED instrument. These now include >1600 individual daily observations obtained with different instrumental configurations (slits, gratings). The provided level 1 data consist of 2D spectra acquired during one day of observation with 1-min resolution. For graphic purpose, the corresponding quickooks are integrated over the full day.

The description of these data is described here. A specific article describing the employed pipeline to derive high-level Hisaki data levels is available here.

VO tools

Florence HENRY — 2018-07-03T14:57:52Z

Cassis Aladin

The interactive use of VO tools 'Aladin' or 'Cassis' (enabled by clicking on the links below each quicklook) requires the user to have launched the relevant software before. The data are then transmitted automatically to the chosen tool through the SAMP protocol.

Cassis is not launched

Florence HENRY — 2018-07-03T14:55:42Z

You have to launch Cassis. See the help section for more details.

Team

Laurent LAMY — 2015-06-30T14:16:24Z

Team

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

Name	Status	Institute	Role
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

Collaborations

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) .

Graphics

Laurent LAMY — 2013-07-16T08:40:10Z

Graphics :

Planetary magnetospheres of the solar system

Credits : S. Cnudde and L. Lamy, LESIA/Observatoire de Paris/CNRS

HST-FUV planetary observations

Credits : L. Lamy, LESIA, STSci, ESA/NASA Hubble Space Telescope

Saturn's aurorae at northern solstice in 2017

Credits : ESA/Hubble, NASA & L. Lamy/Observatoire de Paris

Animated version :
https://cdn.esahubble.org/archives/...

The Uranus' aurorae in 2011

Credits : NASA, ESA, L. Lamy and R. Prangé (Observatory of Paris, CNRS, CNES

The Uranus' aurorae in 2014

(Credits : ESA/Hubble & NASA, L. Lamy / Observatoire de Paris)

The aurorae of Uranus in 2022

Credits : ESA/Hubble, NASA, L. Lamy, L. Sromovsky

Help for VO tools

Florence HENRY — 2013-07-04T13:54:39Z

Images can be interactively read with Aladin.

First option : you can directly use Aladin online with your web browser (applet mode). In this case, simply click on the link "view with Aladin" below the image of interest. The relevant applet will be launched automatically.
Second option : you possess the latest version of Aladin on your computer (if not, you can download it).
In this case, launch the application first, and then click on the link "view with Aladin" below the image of interest.

Spectra can be interactively read with Specview (v2.17.4)

No applet is currently avaiblable. You thus have to download the version 2.17.4 of Specview.
Once Specview launched, click on "Samp > Start" (in the top menu), and then click on the link "view with Specview" below the spectrum of interest. A popup will ask you to choose the lines or the extension you want. Click on "Go" to display the results.

In case of trouble

If the the applet (1st option) or the application (2nd option) is running, but no data are displayed when you click on "view with Aladin/Specview" :

Click on the "Connect" button ;
Check that you do not have any previous application or applet running or blocked in the background ;
Check that pop-ups are not disabled by your web browser (1st option only) ;
Reload this page once the relevant sofwares are opened and click again on the link "view with Aladin/Specview".

If you encounter a persistent issue, please send us an email describing your problem at florence.henry@obspm.fr.

Specview is not launched

Florence HENRY — 2013-07-04T13:51:06Z

You have to launch Specview. See the help section for more details.

Aladin is not launched

Florence HENRY — 2013-07-04T13:50:37Z

You have to launch Aladin. See the help section for more details.