Poor input colour recovery
The sources in this issue were originally found to be much fainter than expected during the validation phase and subsequently their photometry was removed from the Gaia EDR3 catalogue. The cause of this was found to be poor input Spectral Shape Coefficient, SSC, (colour) values. Following this, the transits for these sources were all processed as Bronze sources i.e. using default SSCs, for all three flux types (G, GBP and GRP) and generating weighted mean flux values (and their errors) for each source. This will make the source consistently Bronze. See Section 8.2 of Riello et al. 2020 for more details.
In this file, magnitudes have been generated from the fluxes using the formula:
where the zeropoints are the Gaia EDR3 VEGAMAG ones which can be found in Riello et al. 2020 (Section 7, Table 3).
This issue affects 5,401,215 sources.
Note that the GBP magnitudes will still be affected by the bias mentioned in Section 8.1 of Riello et al. 2020. Care should be taken when using GBP magnitudes fainter than 20.3. See also Section 9.2 for some suggestions on possible filtering criteria.
Download the file
Please connect with an FTP client of your choice or using the terminal to ftp.cosmos.esa.int and navigate to the folder GAIA_PUBLIC_DATA. Here you can find a folder PhotometryEDR3. The file with details on these sources can be found there along with a readme.txt file.
Insufficient valid transits
During the validation of the Gaia EDR3 catalogue, 54,125 sources were found not to have a mean G flux available in the Gaia EDR3 catalogue even though astrometric information was available for them. Investigation showed that these sources had too few valid transits for photometric processing. The validity criteria are different in the photometric and astrometric processing chains.
As a convenience to the user, a median Gvpu on-board magnitude (see Gaia EDR3 Documentation Section 184.108.40.206.3) is provided for these sources, but stored with a reduced precision (10%). This is to stop users misguidedly trying to use these values for science. They are purely a general indicator of the brightness of the source. It must be stressed that these values are uncalibrated and on a different photometric system to that of the G values in Gaia EDR3.
Download the file
The file with details on these sources can be downloaded through this link.