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Astron. Astrophys. Suppl. Ser.
Volume 138, Number 3, September 1999
Gamma-Ray Bursts in the Afterglow Era Contents Rome, November 3-6, 1998
Page(s) 453 - 454
Published online 15 September 1999
DOI: 10.1051/aas:1999305

Astron. Astrophys. Suppl. Ser. 138, 453-454

Broad-band spectral evolution of GRB afterglows

N. Masetti1 - E. Pian1 - E. Palazzi1 - L. Amati1 - T.J. Galama2 - L. Nicastro3 - P.M. Vreeswijk2 - F. Frontera1 - J. van Paradijs2

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1 - Istituto Te.S.R.E., CNR, via Gobetti 101, I-40129 Bologna, Italy
2 - Astronomical Institute "Anton Pannekoek", Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
3 - I.F.C.A.I., CNR, via Ugo La Malfa 153, I-90146 Palermo, Italy

Received December 29, 1998; accepted April 21, 1999


Quasi-simultaneous Spectral Energy Distributions (SEDs) at different epochs of four among the most intensively observed Gamma-Ray Burst (GRB) afterglows have been constructed in order to investigate and compare the temporal evolution of their multiwavelength emission. The data suggest that generally the peak frequency moves toward lower frequencies with time. SED local maxima in the optical/IR range are present in some cases, possibly due to dust absorption within the host galaxy.

Key words: methods: data analysis -- gamma-rays: bursts

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