The Impact of Artificial Space Objects on Optical Astronomy as Determined from 32 Million Photometric Observations

Abstract

Photometric observations of satellites, rockets and space debris brighter than magnitudes 6.0, 7.0 and 8.0 are characterized. Those magnitudes pertain to different levels of interference with astronomy as defined by the International Astronomical Union. The densities of objects per square degree of sky and brighter than the magnitudes listed above are 0.38 e-3, 0.76 e-3 and 1.10 e-3, respectively. Probabilities of objects appearing on astronomical images depend on the field of view and the exposure duration. For objects brighter than magnitude 7.0 the probability that one will appear on a 10 second exposure of a 10 degree square field of view is 15%. The probability that an object is visible to the unaided eye under dark sky conditions is 59%. These percentages represent all nighttime hours. We discuss how they change with the Sun's distance below the horizon. Examination of data for objects launched since the start of the spacecraft constellation era shows that satellites account for most of the bright observations. If the plans of satellite operators to launch a million spacecraft are realized, nearly every astronomical image of a few seconds duration and several degrees in size may be contaminated during several hours of each night. Finally, people viewing the night sky may perceive satellites more strongly than stars.