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The challenge of blending in large sky surveys

Abstract

The increasing sensitivity of modern sky surveys allow ever fainter emissions of light to be detected, but it also increases the chances of noticeable overlap between multiple sources of light, a phenomenon called blending. The consequences of blending are expected to be among the leading systematic measurement uncertainties of future surveys, such as the Legacy Survey of Space and Time. This Perspective discusses two main approaches to addressing blending: attempting to separate individual sources and statistically correcting for the presence of blending at the population level. For both approaches, simultaneous access to data of multiple surveys will be critical to construct a joint data set that combines the strengths of each individual survey.

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Fig. 1: The same sky region of 1.5 × 0.75 arcmin2, observed by different surveys.

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Acknowledgements

J.S. acknowledges that this document was prepared using the resources of the Fermi National Accelerator Laboratory (Fermilab), a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is managed by Fermi Research Alliance, LLC (FRA), acting under contract no. DE-AC02-07CH11359.

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Euclid Deep Fields: https://www.cosmos.esa.int/web/euclid/euclid-survey

Hubble Legacy Archive: https://hla.stsci.edu/

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Melchior, P., Joseph, R., Sanchez, J. et al. The challenge of blending in large sky surveys. Nat Rev Phys 3, 712–718 (2021). https://doi.org/10.1038/s42254-021-00353-y

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