14.1.4 Photometry

Photometry in Gaia DR3 is identical to the one in Gaia EDR3 except for a small (order 0.01 mag) colour-dependent correction to $G$ magnitudes for 2p and 6p solutions.

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  The comparison of Gaia DR3 photometry to external catalogues shows that issues are mainly seen in the bright end, i.e. brighter than 5-6 mag, and in $G_{\mathrm{RP}}$ for $G_{\mathrm{RP}}$ fainter than 18 mag.

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  Comparison with GOG simulations (Section 14.3) shows that at high latitudes the values of $G_{\mathrm{BP}}-G_{\mathrm{RP}}$ for GOG20 and Gaia EDR3 are in good agreement, but not at bright magnitudes where the colour determination seems to be problematic; however, this discrepancy is slightly reduced compared to Gaia DR2.

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  Results of comparison with CALSPEC are globally better than for Gaia DR2 except for $G_{\mathrm{RP}}$, which does not go through zero and confirms the magnitude dependence seen in the Hipparcos comparison. This is inside the expected uncertainties of the libraries and is not considered problematic.

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  The pattern of the ecliptic that was present in Gaia DR2 for sky maps of sources with phot_bp_rp_excess_factor lower than $5$ is no longer visible, meaning that the background due to zodiacal light has been successfully removed.

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  The phot_bp_rp_excess_factor values are improved with respect to Gaia DR2 mainly for faint sources

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  Median differences between Gaia DR2 and Gaia EDR3 photometry in open clusters are very small (Section 14.7), i.e. $-0.0087$ ($G$), 0.0027 ($G_{\mathrm{BP}}$), 0.0074 ($G_{\mathrm{RP}}$), 0.0074 ($G_{\mathrm{BP}}-G_{\mathrm{RP}}$), with dispersions of the order of 0.01-0.02 in $G$, $G_{\mathrm{BP}}$, $G_{\mathrm{BP}}-G_{\mathrm{RP}}$ and lower in $G_{\mathrm{RP}}$. However, for a small sample of stars differences can be higher than 1.5-1.7 mag in $G_{\mathrm{BP}}$ and $G$, possibly related to the small number of observations ().

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  Photometry in crowded fields (globular clusters, Section 14.7) is still worse than in non crowded regions, with deviations both in colour and in magnitude already present at phot_bp_rp_excess_factor $>2$.