We report on the search for optical counterparts of Planck Sunyaev-Zel ’ dovich ( SZ ) cluster candidates using a 0.6 \mathrm { m } non-professional telescope .
Among the observed sources , an unconfirmed candidate , PSZ2 G156.24+22.32 , is found to be associated with a region of more than 100 galaxies within a 3 arcminutes radius around the Sunyaev-Zel ’ dovich maximum signal coordinates .
Using 14 hours of cumulated exposure over the Sloan color filters g ^ { \prime } , r ^ { \prime } , i ^ { \prime } , and z ^ { \prime } , we estimate the photometric redshift of these galaxies at z _ { \mathrm { phot } } = 0.29 \pm 0.08 .
Using the red-sequence galaxy method gives a photometric redshift of 0.30 { } ^ { +0.03 } _ { -0.05 } .
Combined with the Planck SZ proxy mass function , this would favor a cluster of 4.4 \times 10 ^ { 14 } solar masses .
This result suggests that a dedicated pool of observatories equipped with such instruments could collectively contribute to optical follow-up programs of massive cluster candidates at moderate redshifts .