EUI Data Release 4.0 2021-12


"EUI Data Release 4.0 2021-12", released on 2021-12-15 contains the Solar Orbiter/EUI L1, L2 and L3 data for the period 2020-03-03 up till and including 2021-09-15

This period covers the Near Earth Commissioning Phase (NECP) and a large part of the Cruise Phase. This implies that most data is the result of technical tests, for which the instrument configuration was often non-nominal. Most data is therefore a-priori not suitable for scientific analysis but is instead primarily intended as a reference for the further development of analysis and visualisation software.

Data policy, citation & acknowledgements

The "EUI Data Release 4.0 2021-12" is public and can be freely downloaded from the EUI website and from the Solar Orbiter Archive.

Because of the technical and uncalibrated nature of the current release, it is strongly recommended to get in contact with an EUI Consortium member who will provide technical assistance during data handling. In return, co-authorship on eventual publications is expected. If you are not sure who to contact, ask a suggestion to the EUI Principal Investigator Team.

Scientific papers using EUI data are asked to

  1. cite the EUI instrument paper "Rochus et al, AA, 2020".
  2. cite the above DOI to identify which EUI Data Release was used
  3. mention in the acknowledgements "Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. The EUI instrument was built by CSL, IAS, MPS, MSSL/UCL, PMOD/WRC, ROB, LCF/IO with funding from the Belgian Federal Science Policy Office (BELSPO/PRODEX PEA C4000134088); the Centre National d’Etudes Spatiales (CNES); the UK Space Agency (UKSA); the Bundesministerium für Wirtschaft und Energie (BMWi) through the Deutsches Zentrum für Luft- und Raumfahrt (DLR); and the Swiss Space Office (SSO)."
  4. send a notice to as to facilitate cross-referencing and accumulate statistics for future mission and team reviews.

The usage of EUI images as online web graphics or in printed materials should mention "Image Courtesy: ESA/Solar Orbiter/EUI".

List of changes as compared to EUI Data Release 3.0

List of changes as compared to EUI Data Release 2.0

List of changes as compared to EUI Data Release 1

Level 1 data

Level 1 data implies that the metadata in the FITS keywords is complete but that the images remain uncalibrated. Besides decompression, only limited, reversible operations have been applied to the images (mirroring & flipping, and 90-degree rotations) such that solar north is roughly on top and solar east roughly on the left. All the images received on the ground are distributed in the Level 1 dataset. This includes many images with the telescope doors still closed, either "darks" or "LEDs" (calibration lamp images). The first of these were received on March 3, 2020.

This release contains 45336 L1 files.

Level 2 data

The euiprep python routine takes the Level 1 data and rectifies instrument deviations for which corrections are available. It also updates the WCS FITS keywords to correct for spacecraft pointing instabilities. The output of these calibration steps is distributed as Level 2 data. The euiprep routine is in an early development phase and in continuous evolution. The Level 2 data are thus a snapshot of the best available corrections at the time of the Level 2 data production.

The git version number of the euiprep S/W used to generate these L2 files is copied in the FITS header HISTORY keyword. For this release, the git SHA (first 8 characters) are (see also FITS header VERS_CAL keyword): - '7ca3ae80' - 'addaf6df' for the HRI-EUV files that were missing in release V3 due to a bug.

The euiprep routine is only applied to lossless compressed or uncompressed Level-1 solar images, starting with the 'first light' images on May 12, 2020. Technical images such as e.g. darks or LEDs are not processed into Level-2 data. The selection is done with the IMGTYPE keyword which is set to IMGTYPE="solar image" if * both the heat shield doors and instrument doors are open, AND * no LED is on AND * if the telescope has a filter wheel, that this filter is not in a blocking position.

For HRILYA, extra conditions are added to make sure the Screen and MCP voltages were properly configured for solar imaging. For HRILYA images with exposure time less or equal than 3s (XPOSURE LE 3.0) we require

LYACSCR > 3450 AND ((GAINCOMB="low-only" AND LYACMCP> 580) OR (GAINCOMB="high-only" AND LYACMCP> 450))

For HRILYA images with exposure time larger than 3s (XPOSURE GT 3.0) we require

LYACSCR > 3450 AND ((GAINCOMB="low-only" AND LYACMCP> 480) OR (GAINCOMB="high-only" AND LYACMCP> 350))

For FSI an extra 20 images have been added to the Level 2 release with IMGTYPE="unknown image", that correspond to 'occulted images' (see known issues below).

This release contains 37845 L2 files.

The L2 file version number is incremented every time the L2 file is updated and may thus differ from the L1 file version number.

Level 3 data

Level 3 data corresponds to a further processing of Level 2 data for visualisation purposes. The Level 3 image files are intended for visualisation through JHelioviewer. L2 images without the keyword WAVELNTH (e.g., because a wrong filter position was selected) are excluded from processing.

This release contains 37840 L3 files.

The L3 file version number is identical to the L2 file version number.

Known remaining issues