We have recently made public a preprint [1] about a very specialized work in which we have tested the feasibility to use small telescopes to make optical follow-up of Planck cluster candidates detected by the Sunyaev-Zel’dovich effect.
The above picture shows the redshift distribution obtained over a hundred objects, most probably galaxies, detected within \(3'\) from the center of an unconfirmed Planck’s SZ candidate.
In summary, with a 0.6 meter telescope, photometric redshift measurements are possible in a redshift range of \(z_{\mathrm{phot}} \simeq 0.1\) up to \(z_{\mathrm{phot}} \gtrsim 0.6\). This opens-up the possiblity for amateur astronomers to collectively contribute to SZ candidate validation with basic observables such as \(z_\mathrm{phot}\) and galaxy counts.