A NICER look at X-ray cross-calibration

NICER has now been observing the sky for over 5 years and has participated in several coordinated cross-calibration efforts. These observations have covered roughly 20 different targets (e.g., 3C 273, Crab, Cas A, LMC X-3), which have been simultaneously observed by NICER in combination with either Swift, Chandra, XMM-Newton, and/or NuSTAR. Here we report on the results of the analysis of these observations, including fluxes in various overlapping bands and a comparison of best-fit model parameters for each observatory. We also report on searches for systematic variations in cross-calibration over time. Lastly, we will discuss the impact of using different NICER background models on cross-calibration.