Impact of Starlink constellation on Early LSST: a Photometric Analysis of Satellite Trails with BRDF Model

We report a simulation and quantification of the impact of the Starlink constellation on LSST in terms of the trail surface brightness using a BRDF-based satellite photometric model. A total of 11,908 satellites from the Gen1 and Gen2A constellations are used to focus on the interference to the initial phase of LSST operation. The all-sky simulation shows that approximately 69.33% of the visible satellites over station have an apparent brightness greater than 7 mag with a v1.5 satellite model. The impact of satellite streaks exhibit a non-monotonic relationship to the solar altitude, with the worst moments occurring around $-15^{\circ}$ solar altitude. The assessment based on simulated schedules indicates that no trails can reach the saturation-level magnitude, but 71.61% trails show a surface brightness brighter than the best-case crosstalk correctable limits, and this percentage increases as the dodging weight increases. Therefore, avoiding satellites in the scheduler algorithm is an effective mitigation method, but both the number of streaks and their brightness should be taken into account simultaneously.