Prompt optical detection of GRB 050401 with ROTSE-IIIa
The ROTSE-IIIa telescope at Siding Spring Observatory, Australia, detected prompt optical emission from Swift GRB 050401. We present observations of the early optical afterglow, first detected by the ROTSE-IIIa telescope 33 s after the start of γ-ray emission, contemporaneous with the brightest peak of this emission. This GRB was neither exceptionally long nor bright. This is the first prompt optical detection of a GRB of typical duration and luminosity. We find that the early afterglow decay does not deviate significantly from the power-law decay observable at later times and is uncorrelated with the prompt γ-ray emission. We compare this detection with the other two GRBs with prompt observations, GRB 990123 and GRB 041219a. All three bursts exhibit quite different behavior at early times. © 2005. The American Astronomical Society. All rights reserved.
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Rykoff, E., Yost, S., Krimm, H., Aharonian, F., Akerlof, C., Alatalo, K., Ashley, M., Barthelmy, S., Gehrels, N., Göǧüş, E., Güver, T., Horns, D., Kiziloǧlu, Ü., McKay, T., Özel, M., Phillips, A., Quimby, R., Rujopakarn, W., Schaefer, B., Smith, D., Swan, H., Vestrand, W., Wheeler, J., & Wren, J. (2005). Prompt optical detection of GRB 050401 with ROTSE-IIIa. Astrophysical Journal, 631 (2 II) https://doi.org/10.1086/497370