Identified as Monastery of Christ Pantepoptes. See also: https://www.thebyzantinelegacy.com/pantepoptes.
Cistern concordance (Crow et al., 2008, p. 147): Forchheimer and Strzygowski 1893: 106-7 no. 2; Kleiss 1965a: no. 88; Müller-Wiener 1977: 193, 409.