Hello! I have recently upgraded from v2.6 to v.3 of yt and I'm having some difficulties 1) I was trying to use the Phox module to generate an x-ray mock observation from a simulated galaxy cluster, however the code gives a memory error while generating "PhotonList"; when doing $top I can see the code taking up to 24Gb of memory. This happens if I select a spherical region bigger than 100 kpc. Simulation details: I have a 200 Mpc cosmological simulation made in Flash, the smallest resolution cells are 14Kpc. Ideally, I would like to generate a mock observation of at least 5mpc... is this simply not possible? Any ideas how to tackle this issue? 2) The syntax of the first projection PHOX example is a bit strange. shouldn't it be >ds.add_field instead?, Otherwise, we get NameError:name 'add_field' is not defined Thanks for any suggestions/help! Barbara L. Ramirez M. MSc. Institut für Astro- und Teilchenphysik University of Innsbruck