Metis Data Release 1.0
The purpose of this document is to provide information on the Metis Data Release 1.0, such that the user can technically work with these data and know their potential and limitations.
The Metis Data Release 1.0, released since 2022-07-25, contains the Solar Orbiter/Metis L2 data acquired in the period 2021-12-03 up till and including 2022-04-10. This period covers the beginning of the Nominal Mission Phase (NMP) from STP180 to STP197, under variable instrument configurations.
Access to data
The Metis Data Release 1.0 is public and can be freely downloaded through the Solar Orbiter Archive.
Technical support to the Metis data
Because of the technical and the preliminary calibrated nature of the current release, it is strongly recommended to get in contact with a Metis Team 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 Metis Principal Investigator. On request, the Metis Team is glad to provide technical support.
Citation and acknowledgements
When using Metis data, the authors of scientific papers are asked to:
- cite the Metis Instrument paper;
- cite the DOI to identify which Metis Data Release was used;
- include the following statement in the acknowledgements "Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. Metis was built and operated with funding from the Italian Space Agency (ASI), under contracts to the National Institute of Astrophysics (INAF) and industrial partners. Metis was built with hardware contributions from Germany (Bundesministerium für Wirtschaft und Energie through DLR), from the Czech Republic (PRODEX), and from ESA".
The usage of Metis images as online web graphics or in printed materials should mention "Image courtesy: ESA/Solar Orbiter/Metis".
Co-authorship of the Metis Team people in charge of the planning of the acquisitions involved during the period covered in the present Data Release is expected. Please refer to this table (link) for the list of people responsible of each STP.
Please send a notice to firstname.lastname@example.org as to facilitate cross-referencing and accumulate statistics for future missions and team reviews.
Metis science data description and disclaimer
Metis data products are processed at various levels ranging from Level 0 to Level 3.
- Level 0 (L0): uncalibrated data (units of DN) obtained from telemetry packets that are uncompressed and formatted in standard FITS format. The FITS headers contain only information that is available from the telemetry packet headers.
- Level 1 (L1): uncalibrated data (units of DN). The metadata contains extra engineering data from housekeeping telemetry packets and scientific coordinate systems (WCS) keywords.
- Level 2 (L2): data calibrated to physical units and ready for the scientific analysis. They consist of VL fixed-polarization, polarised-brightness, total-brightness, polarization-angle, and Stokes parameters images, and UV images. Corrections for bias, dark-current, flat-field, and vignetting are applied together with exposure normalization, pointing adjustment, and radiometric calibration. All available orbital and attitude information is used and coordinates are expressed in scientific coordinate systems (WCS).
- Level 3 (L3): science data derived from L2 data obtained after scientific analysis, i.e., movies, Carrington maps, electron-density maps, solar-wind outflow velocity maps, etc.
General users are recommended to use L2 data (and, if available L3 data) from the latest release for essentially all scientific analyses, both qualitative and quantitative. L0 and L1 data are only relevant for users who wish to study the data calibration process and will be available only upon request.
The production of Metis public data reflects current instrument calibration as determined by the Metis science team. Calibration efforts are ongoing and public data will be updated over the course of the mission based on improved understanding of instrument response. Each such data reprocessing will be distributed as a new release of the data and new data will be added to the current releaseuntil a reprocessing is needed. Previous versions of the data, corresponding to old releases, will continue to be available for reproducibility of past research.
Data are provided in the standard FITS format with the following naming convention according to ESA/Solar Orbiter standards:
- descriptor is a string which uniquely identifies the data type in the file (for the details, please refer to the Appendix B of the Solar Orbiter/Metis Data Product Description Document;
- datetime is the timestamp of the data in the file, i.e., the UTC at which the observation was made by the spacecraft;
- version is the version of the FITS file.
This section contains a summary of limitations and data issues that were known and documented at the release date.
- Stray light: VL and UV images are not corrected from stray light.
- Debris: VL images sometimes exhibit multiple luminous stripes or patches that sometimes extend over a significant portion of the image and may be detected moving in several consecutive frames. These patterns can typically be attributed to debris passing in front of the instrument aperture.
- UVD anomaly: The UV channel is affected by some anomalies that temporarily alter the instrument response in the UV channel. For instance, brightenings over the entire or large parts of the detector, lasting from minutes or hours, can be detected. These anomalies are under active investigation, and are not corrected yet in the present data release. It is strongly suggested to contact the Metis Team (email@example.com) to verify the presence of known anomalies in any specific UV data set.
- Fixed pattern noise: The present calibration pipeline does not fully correct from the fixed pattern noise that can be seen in the VL channel images as a periodic column or row pattern.
- Vignetting function: The vignetting was measured during the on-ground characterization, and has been synthetically adapted to the in-flight occulting configuration. The occulting configuration has changed due to launch activity with subsequent internal occulter realignment. Deviations from the true vignetting function are most evident in the inner FoV.
- Optical performance: For spatial resolution and other optical performance, please refer to Antonucci et al., 2020. Updated values of plate scale and vignetting function for the UV channel are given in Andretta et al., 2021.
- Error matrices: Metis L2 FITS files come with an estimate of the data uncertainty provided in a FITS extension named “Error matrix”; however, in the present data release error matrices are still preliminary and should not be used for quantitative analysis.
- Ghost images: In case a very bright object - like a planet - is present in the instrument FOV, some ghost images may appear in the form of few luminous spots. These spots can be observed in a region more or less symmetrical to the planet with respect to the image center.
For information on data quality, content, and availability, please contact the Metis Team.
For further information please refer to the following documentation:
- the Metis Instrument paper;
- a preliminary version of the Metis Data User Guide (coming soon);
- the Solar Orbiter/Metis Data Product Description Document containing the detailed description of the Metis FITS files structure and the processing steps required to produce the L2 data
- the Metis Data Products and Publication Policy.