Author(s): Jovan Veljanoski, Amina Helmi, Davide Massari, Maarten Breddels
We compare the statistical
properties of four small regions on the sky by quantifying the degree of clustering and correlations between different observables, using the Kullback-Leibler divergence (KLD hereafter). This test allow us to establish whether any observables
or a combination of thereof exhibit unexpected properties.
The selected regions on the sky are circular, have a radius of 5 , and for symmetry purposes are centred on
(,) = (-90, -45), (-90, 45), (90, -45) and (90, 45).
‘patch-b’, ‘patch-c’, and ‘patch-d’, respectively. The
regions contain 350 000 stars on average: ‘patch-a’ and ‘patch-d’ cover regions of high number of transits, while
‘patch-b’ and ‘patch-c’ have fewer transits. This choice reflects our expectation that different groups of observables will have differing distributions depending on the location on the sky, but also on the number
of photometric or astrometric observations. For example
Figure 10.32 shows how phot_g_n_obs
varies across the field of each of the four patches.
We perform our tests also on a few subsets, as listed in Table 10.5. Furthermore, we have performed the KLD tests with and without the rescaling of the astrometric
uncertainties by the factor used to reweight the uncertainties (Lindegren et al.2018, Appendix A), but we found no differences.
Table 10.5: Subsets of pre-DR2 release (1 734 629 872 sources) which have been created for further analysis and comparisons. DUPMATB is the final DR2 Catalogue.