eROSITA-DE Data Release 1 (DR1)

The eROSITA-DE DR1 comprises data from the first six months of the SRG/eROSITA all-sky survey (eRASS1) whose proprietary rights lie with the German eROSITA consortium.

In the Early Data Release (EDR), the data taken during the Calibration and Performance Verification (Cal-PV) phase were released. The reprocessed EDR observations are not part of DR1.

The primary data products of the eROSITA-DE DR1 consist of calibrated event files, which contain the information generated by the cameras used during the eRASS1 observations. The eSASS4DR1 pipeline creates these event files after the received telemetry data from eROSITA of each observation has been reformated, packaged, and archived by a pre-processor. Note that the coverage of the sky is not uniform, i.e., not all observations have been performed with all seven eROSITA TMs (see here).

The eROSITA-DE team has divided the eRASS1 observations into 4700 sky tiles for practical purposes. Each sky tile has a size of 3.6x3.6 square degrees, overlapping by approximately 20 arcmin. The figure below illustrates the sky division:

Tiling of the sky into equal-area overlapping 3.6x3.6 square degrees tiles into which the eRASS1 data is organised and analysed by the pipeline.

Of the 4700 sky tiles, eROSITA-DE have proprietary rights on 2248 of them, and 199 sky tiles have shared rights between the German and Russian consortiums. eROSITA-DE DR1 comprises 2447 sky tiles in total, of which 199 have partial eROSITA-DE data. The FITS table here, shows the boundaries and center coordinates of these 2447 sky tiles.

The released calibrated event lists of each sky tile contain photons:

• with energies between 0.2—10 keV;
• flagged as flag=0xE000F000, i.e., good events from the nominal field of view, excluding bad pixels (click here for further information about flags);
• with patterns pattern=15, i.e., including single, double, triple and quadruple events (access here to learn more about pattern fractions).

Besides calibrated event lists, the eROSITA-DE team also releases the following products per sky tile:

• Images.
• Exposure maps.
• Background maps.
• Tables containing cumulative survey area as a function of limiting flux (for sources with likemin>5).
• Sensitivity maps based on aperture photometry. Includes aperture-averaged exposure maps, aperture-integrated background maps, and area curves (survey area sensitive to a given count rate).
• Sensitivity maps (for sources with likemin>5).
• Source data products.

The images and exposure maps are offered in seven different energy bands:

• 0.2—0.6 keV (021),
• 0.6—2.3 keV (022),
• 2.3—5.0 keV (023),
• 0.2—2.3 keV (024),
• 0.2—0.5 keV (025),
• 0.5—1.0 keV (026),
• 1.0—2.0 keV (027),

while the background maps and the sensitivity maps based on aperture photometry are released only for the first four energy bands above. The tables that contain the cumulative survey area and the sensitivity maps are obtained from the 1B and 3B (one-band and three-band) catalogues. The 1B catalogue was obtained from images in the 0.2—2.3 keV energy band, while the 3B catalogue was obtained by multi-band fitting using the 0.2—0.6 keV, 0.6—2.3 keV, and 2.3—5.0 keV energy bands.

We also offer upper limits per sky positions in four energy bands:

• 0.2—0.6 keV (021),
• 0.6—2.3 keV (022),
• 2.3—5.0 keV (023),
• 0.2—5.0 keV (02e),

The source data products are released for all detected sources in the 1B (one-band) catalogue with DET_LIKE_0>20. These products include source and background spectra, their respective ARFs and RMFs, light curves, and source and background event lists. All these source products are offered per telescope module and combined (see here).

A detailed description of the data and source products can be found under the DR1 data and source products description section. Use the eSASS4DR1 tasks to obtain individual camera event lists and to analyse the data (see Cookbook and eSASS task descriptions).

The eROSITA-DE DR1 data can be retrieved by using the eROSITA-DE Data (eRODat) tool. This tool offers an all-sky view of the eROSITA-DE data, a multi-wavelength view of the eROSITA-DE detected sources, etc. Users are encouraged to explore eRODat and get familiar with all its functionalities.

Upper limit data can be retrieved by using the Upper limits facility.