Londinium : Constantine I : astrological helmet

Constantine I augustus —struck by Constantine I London, 323-324 obv.- CONSTANTINVS AG; Helmeted, cuirassed bust left. Helmet decorated with starry sky / constellation rev.- BEAT TRANQLITAS; Globe on altar inscribed VOT/IS/XX in three lines; above, three stars; PLON in ex RIC VII Lon 269 21mm; 3.0g This helmet has an unusual astronomical or astrological design with a starry sky. Possibly this depicts the Pleiades, a known constellation, with three planets or brighter stars. I recently noticed a second coin with this design (coin #2 in this lot: http://www.cngcoins.com/Coin.aspx?CoinID=136448), which uses the same obverse die as mine. (Still ticked off that someone else bought it...)