Yazar "Aharonian, F." seçeneğine göre listele

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    Exploring broadband GRB behavior during ?-ray emission
    (Iop Publishing Ltd, 2007) Yost, S. A.; Swan, H. F.; Rykoff, E. S.; Aharonian, F.; Akerlof, C. W.; Alday, A.; Ashley, M. C. B.
    The robotic ROTSE-III telescope network detected prompt optical emission contemporaneous with the gamma-ray emission of Swift events GRB 051109A and GRB 051111. Both data sets have continuous coverage at high signal-to-noise levels from the prompt phase onward, and thus the early observations are readily compared to the Swift XRT and BAT high-energy detections. In both cases, the optical afterglow is established, declining steadily during the prompt emission. For GRB 051111, there is evidence of an excess optical component during the prompt emission. The component is consistent with the flux spectrally extrapolated from the gamma-rays, using the gamma-ray spectral index. A compilation of spectral information from previous prompt detections shows that such a component is unusual. The existence of two prompt optical components-one connected to the high-energy emission, the other to separate afterglow flux, as indicated in GRB 051111-is not compatible with a simple external-external'' shock model for the GRB and its afterglow.
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    Prompt optical observations of GRB 080330 and GRB 080413A
    (Amer Inst Physics, 2008) Yuan, F.; Rykoff, E. S.; Schaefer, B. E.; Rujopakarn, W.; Guever, V; Aharonian, F.; Akerlof, C. W.
    We report on the results of rapid responses to GRB 080330 and GRB 080413A by the ROTSE-IIIb and ROTSE-IIIc telecopes. In both cases, optical follow-up started during the prompt emission phase and recorded optical flares peaking at similar times as the last hard X-ray pulses detected by the Swift BAT. For both events, the XRT observations started at the end of the prompt BAT detection and displayed an evolution in time opposite to the optical lightcurve. These very early observations provide us an opportunity to probe the onset of afterglow for these two events.
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    ROITSE-III performance in the swift era
    (Amer Inst Physics, 2006) Yost, S. A.; Rykoff, E. S.; Aharonian, F.; Akerlof, C. W.; Ashley, M. C. B.; Barthelmy, S.; Gehrels, N.
    We report the successful performance of the Robotic Optical Transient Search Experiment (ROTSE) to promptly-disseminated Swift GRB triggers. ROTSE-III is a worldwide network of 4 unfiltered 0.45m optical telescopes. The telescopes operate robotically, automatically responding to GRB position triggers with a preset observations sequence. Including weather and other downtime, ROTSE-III can immediately respond to similar to 40% of Swift trigger positions, with shutter open within approximately 6-8 seconds from the trigger dissemination. We discuss improvements made possible in the automated response the the small, accurate Swift error boxes. We report ROTSE-III's general results, including OTs discovered or confirmed, the distribution of imaging start times relative to the GRB duration, and an overview of OT lightcurves.
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    ROTSE-III performance in the Swift era
    (2006) Yost, S.A.; Rykoff, E.S.; Aharonian, F.; Akerlof, C.W.; Ashley, M.C.B.; Barthelmy, S.; Gehrels, N.
    We report the successful performance of the Robotic Optical Transient Search Experiment (ROTSE) to promptly-disseminated Swift GRB triggers. ROTSE-III is a worldwide network of 4 unfiltered 0.45m optical telescopes. The telescopes operate robotically, automatically responding to GRB position triggers with a preset observations sequence. Including weather and other downtime, ROTSE-III can immediately respond to ?40% of Swift trigger positions, with shutter open within approximately 6-8 seconds from the trigger dissemination. We discuss improvements made possible in the automated response the the small, accurate Swift error boxes. We report ROTSE-III's general results, including OTs discovered or confirmed, the distribution of imaging start times relative to the GRB duration, and an overview of OT lightcurves. © 2006 American Institute of Physics.
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    Status of the ROTSE-III telescope network
    (Wiley-V C H Verlag Gmbh, 2006) Yost, S. A.; Aharonian, F.; Akerlof, C. W.; Ashley, M. C. B.; Barthelmy, S.; Gehrels, N.; Gogus, E.
    ROTSE-III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of gamma-ray burst (GRB) afterglows as close as possible to the start of gamma-ray emission. ROTSE-III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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    Taking a broad view of prompt emission
    (Soc Italiana Fisica, 2006) Yost, S. A.; Aharonian, F.; Akerlof, C. W.; Ashley, M. C. B.; Barthelmy, S.; Gehrels, N.; Gogus, E.
    We discuss the diversity of prompt Gamma-Ray Burst (GRB) spectra from high to low energies, comparing optical observations to simultaneous garnma-ray emission. These events show a wide variety of relations between gamma-ray and optical spectral and temporal properties. Using optical detections and limits from ROTSE as well as the literature, we constrain the broad-band spectral shape during GRB events. With no single result for low-energy emission behavior, GRB models will need to account for diverse outcomes.
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    The dark side of ROTSE-III prompt GRB observations
    (Iop Publishing Ltd, 2007) Yost, S. A.; Aharonian, F.; Akerlof, C. W.; Ashley, M. C. B.; Barthelmy, S.; Gehrels, N.; Goegues, E.
    We present several cases of optical observations during gamma-ray bursts (GRBs) which resulted in prompt limits but no detection of optical emission. These limits constrain the prompt optical flux densities and the optical brightness relative to the gamma-ray emission. The derived constraints fall within the range of properties observed in GRBs with prompt optical detections, although at the faint end of optical/gamma-ray flux ratios. The currently accessible prompt optical limits do not require a different set of intrinsic or environmental GRB properties, relative to the events with prompt optical detections.