The ROTSE-IIIc telescope at the HESS site, Namibia, obtained the earliest detection of optical emission from a gamma-ray burst (GRB), beginning only 21.8 s from the onset of Swift GRB 050801. The optical light curve does not fade or brighten significantly over the first ∼250 s, after which there is an achromatic break and the light curve declines in typical power-law fashion. The Swift XRT also obtained early observations starting at 69 s after the burst onset. The X-ray light curve shows the same features as the optical light curve. These correlated variations in the early optical and X-ray emission imply a common origin in space and time. This behavior is difficult to reconcile with the standard models of early afterglow emission. © 2006. The American Astronomical Society. All rights reserved.
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Rykoff, E., Mangano, V., Yost, S., Sari, R., Aharonian, F., Akerlof, C., Ashley, M., Barthelmy, S., Burrows, D., Gehrels, N., Göǧüş, E., Güver, T., Horns, D., Kiziloǧlu, Ü., Krimm, H., Mckay, T., Özel, M., Phillips, A., Quimby, R., Rowell, G., Rujopakarn, W., Schaefer, B., Smith, D., Swan, H., Vestrand, W., Wheeler, J., Wren, J., & Yuan, F. (2006). The anomalous early afterglow of GRB 050801. Astrophysical Journal, 638 (1 II) https://doi.org/10.1086/501007