"If you look at the right side of the transept wall, you can see that part of the cornice has been cut away to provide the effect. The markings were made by the astronomer, mathematician, archaeologist, historian and philosopher Francesco Bianchini. Bianchini had been commissioned by Pope Clement XI to make them for the Holy Year of 1700. It took a bit longer; they were comleted in 1703 with the assistance of the astronomer G.F. Maraldi." - Exseminarians Churches of Rome
This portion of the basilica, known as the Chapel of St. Bruno, was designed by Carlo Maratta. The altar was made from an older altar by Francesco Fontana in 1864. Above the altar is Giovanni Odazzi's painting The Apparition of the Virgin Mary to St Bruno. It was painted for the 1700 Jubilee, and shows the Blessed Virgin handing the Order's Rule to St Bruno. The vault was painted by Andrea Procaccini with figures of the Evangelists, while the rest of the decorations were painted by Antonio Bicchierai.
Later, I was chatting with another visitor and she asked me if I had not seen the coin boxes that you can place money in so lights will come up for a few moments to assist you in your photography. I didn't notice any boxes or signage to that affect in this church.