Optimal Coaddition of Imaging Data for Rapidly Fading Gamma-Ray Burst Afterglows - AstrophysicsReport as inadecuate




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Abstract: We present a technique for optimal coaddition of image data for rapidlyvarying sources, with specific application to gamma-ray burst GRB afterglows.Unweighted coaddition of rapidly fading afterglow lightcurve data becomescounterproductive relatively quickly. It is better to stop coaddition of thedata once noise dominates late exposures. A better alternative is to optimallyweight each exposure to maximize the signal-to-noise ratio S-N of the finalcoadded image data. By using information about GRB lightcurves and image noisecharacteristics, optimal image coaddition increases the probability ofafterglow detection and places the most stringent upper limits onnon-detections. For a temporal power law flux decay typical of GRB afterglows,optimal coaddition has the greatest potential to improve the S-N of afterglowimaging data relative to unweighted coaddition, when the decay rate is high,the source count rate is low, and the background rate is high. The optimalcoaddition technique is demonstrated with applications to SwiftUltraviolet-Optical Telescope UVOT data of several GRBs, with and withoutdetected afterglows.



Author: A. N. Morgan, D. E. Vanden Berk, P. W. A. Roming, J. A. Nousek, T. S. Koch, A. A. Breeveld, M. de Pasquale, S. T. Holland, N. P.

Source: https://arxiv.org/







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