With the advent of the European Space Agency's Gaia mission and its recent data releases EDR3 and DR3, the astronomy community has obtained the largest-ever cartograph of our Milky Way galaxy with unprecedented astrometric parameters. In this paper, we have presented a catalogue of ~47 million halo stars on the main sequence with high tangential velocity selected only using Gaia DR3 proper motions and photometry. This is made possible using the reduced proper motion that when plotted versus Gaia colours mimics the colour-magnitude diagram for populations with different tangential velocities. The distance makes up an important aspect of the 6D information often used in the study of the dynamical evolution of the Milky Way halo. Here, we calculate photometric distances to these stars with simple linear colour-magnitude relation for these stars on the main sequence. The typical uncertainty on these derived photometric distances is ~7% which is more reliable and probes farther away than would be possible using Gaia parallaxes. Using the colour range 0.45<(G-G_RP_)<0.715 where the main sequence is narrower, gives an even better accuracy down to 0.39kpc in distance. The distribution of these sources in the sky, together with their tangential component velocities, are very well-suited to study retrograde substructures. We explore the selection of two complex retrograde streams: GD-1 and Jhelum. For these streams, we resolve the gaps, wiggles and density breaks reported in the literature more clearly and also derive metallicity dependent distances. We also illustrate the effect of the kinematic selection bias towards high proper motion stars and incompleteness at larger distances due to Gaia's scanning law. These examples showcase how the full RPM catalogue made available here can help us paint a more detailed picture of the build-up of the Milky Way halo. It is a golden age to do Galactic Archaeology. Such a main sequence stars sample with the largest halo cartograph in the era of Gaia can also be used to provide spectroscopic targets to the next big spectroscopic surveys such as WEAVE, 4MOST, and SDSS-V because this catalogue complements the Gaia DR3 source spectra at the fainter end. Even low-resolution spectroscopic follow-up that can provide us with the missing line-of-sight velocities and/or metallicities can be extremely useful to disentangle the merger history of the inner stellar halo.

Cone search capability for table J/MNRAS/521/2087/rpmgaia3 (Full reduced proper motion halo catalogue)

Cone search capability for table J/MNRAS/521/2087/gd-1 (Member candidates of the stellar stream GD-1)

Cone search capability for table J/MNRAS/521/2087/gd-1-rv (Member candidates of the stellar stream GD-1 with radial velocities from SDSS SEGUE)

Cone search capability for table J/MNRAS/521/2087/jhelum (Member candidates of the stellar stream Jhelum)

Cone search capability for table J/MNRAS/521/2087/sgr (Member candidates of part of the stellar stream Sagittarius)

Cone search capability for table J/MNRAS/521/2087/sgr-rv (Member candidates of part of the stellar stream Sagittarius with radial velocities from SDSS SEGUE)