The number 1473 in white appears on recto over the shadow of Antoin Sevruguin's camera. Titled "Reza" on verso in what may be Antoin Sevruguin's hand.
Publications
A variation of this photograph (where Antoin Sevruguin has moved closer to the hanging), has the number 623 in white on verso over the shadow of the man taking the photograph at the time.
The image is reproduced on page 15 of Volume I of “Du Khorassan au pays des Backhtiaris: trois mois de voyage en Perse” by Henry-Rene D’Allemagne published in 1911 by Hachette, Paris, France. The image is titled "Le meidan a Teheran: Execution de dare Mirza Riga, assasisin de Naser-ed-Dine Shah".