Gaia DR2 photometric sensitivity curves

This library defines new sensitivity curves for G, G_BP_, and G_RP_ using a functional analytical formalism. The new sensitivity curves are significantly better than the two previous attempts we use as a reference, REV (Evans et al., 2018A&A...616A...4E, Cat. I/345) and WEI (Weiler, 2018A&A...617A.138W, Cat.

J/A+A/617/A138). For G we confirm the existence of a systematic bias in magnitude and correct a color term present in REV. For G_BP_ we confirm the need to define two magnitude ranges with different sensitivity curves and measure the cut between them at G_phot_=10.87mag with a significant increase in precision.

The new curves also fit the data better than either REV or WEI. For G_RP_, our new sensitivity curve fits the STIS spectra better and the differences with previous attempts reside in a systematic effect between ground-based and HST spectral libraries. Additional evidence from color-color diagrams indicate that the new sensitivity curve is more accurate.

Nevertheless, there is still room for improvement in the accuracy of the sensitivity curves because of the current dearth of good-quality red calibrators: adding more to the sample should be a priority before Gaia data release 3 takes place.