Utilizing simulated event lists in IACT gamma-ray astronomy

We present a new approach for calculating the IACT detector response of high-level analyses with publicly available software based on dedicated simulations of the individual observations. For each of them, a corresponding event list is exported, paralleling the event list of the actual data. The information contained in these simulated lists can be utilized flexibly, without the need for but also being able to reduce it to the standard IRF scheme. We show that standard IRFs from simulated event lists yield consistent results, illustrating the validity of the concept. To improve on the standard response generation, we then demonstrate how to calculate the final IRFs for a given analysis geometry directly from the simulated event lists. The result is a more accurate description, where the change in IRF methodology leads to considerable differences. Finally, we introduce a new method of generating background models based on simulated event lists. By properly considering observation and detector conditions, the new approach provides an accurate description of the γ -like background, exhibiting good stability and a moderate systematics level.