The three bright spots in Reber's map are as follows
(using his map for his coords, B1950 values from the literature
for "true" coords)

    1.  the center of the Milky Way:

            Reber's spot:   RA = 18     Dec = -25
            Sgr A*:              17:42        -29


    2.  Cygnus A

            Reber's spot:   RA = 20:20  Dec = +41
            Cyg A:               19:57        +40


    3.  Cassiopeia arm -- no obvious single source

            Reber's spot:   RA = 23:10  Dec = +49
            Cas A:               23:21        +58    not a close match