Spot-Based Measurement of the Brighter-Fatter Effect on a Roman Space Telescope H4RG Detector and Comparison with Flat-Field Data

We present the measurement and characterization of the brighter-fatter effect (BFE) on a NASA Roman Space Telescope development Teledyne H4RG-10 near-infrared detector using laboratory measurements with projected point sources. After correcting for other interpixel non-linearity effects such as classical non-linearity and inter-pixel capacitance, we quantify the magnitude of the BFE by calculating the fractional area change per electron of charge contrast. We also introduce a mathematical framework to compare our results with the BFE measured on similar devices using autocorrelations from flat-field images. We find an agreement of 18 +/- 5% between the two methods. We identify potential sources of discrepancy and discuss future investigations to characterize and address them.