J/A+A/607/A29 GRB 120327A afterglow colour variations (Melandri+, 2017)
Colour variations in the GRB 120327A afterglow.
Melandri A., Covino S., Zaninoni E., Campana S., Bolmer J., Cobb B.E.,
Gorosabel J., Kim J.-W., Kuin P., Kuroda D., Malesani D., Mundell C.G.,
Nappo F., Sbarufatti B., Smith R.J., Steele I.A., Topinka M., Trotter A.S.,
Virgili F.J., Bernardini M.G., D'Avanzo P., D'Elia V., Fugazza D.,
Ghirlanda G., Gomboc A., Greiner J., Guidorzi C., Haislip J.B., Hanayama H.,
Hanlon L., Im M., Ivarsen K.M., Japelj J., Jelinek M., Kawai N.,
Kobayashi S., Kopac D., LaCluyze A.P., Martin-Carrillo A., Murphy D.,
Reichart D.E., Salvaterra R., Salafia O.S., Tagliaferri G., Vergani S.D.
<Astron. Astrophys. 607, A29 (2017)>
=2017A&A...607A..29M 2017A&A...607A..29M (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays; Photometry, UBVRIJKLMNH; Photometry, ugriz; Magnitudes
Keywords: gamma-ray burst: individual: GRB 120327A - dust, extinction
Abstract:
We present a comprehensive temporal and spectral analysis of the long
Swift GRB120327A afterglow data to investigate the possible causes of
the observed early time colour variations. We collected data from
various instruments/telescopes in X-ray, ultra-violet, optical and
near-infrared bands and determined the shapes of the afterglow
early-time light curves. We studied the overall temporal behaviour and
the spectral energy distributions from early to late times. The
ultra-violet, optical, and near-infrared light curves can be modelled
with a single power-law component between 200 and 2x104s after the
burst event. The X-ray light curve shows a canonical
steep-shallow-steep behaviour, typical of long gamma-ray bursts. At
early times a colour variation is observed in the ultra-violet/optical
bands, while at very late times a hint of a re-brightening is visible.
The observed early time colour change can be explained as a variation
in the intrinsic optical spectral index, rather than an evolution of
the optical extinction.
Description:
Photometric data of GRB120327A are presented. Magnitudes are in the
Vega system unless for griz filters that are in the AB system, and
they are all not corrected for Galactic absorption. Errors are at
1sigma level.
Objects:
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RA (2000) DE Designation(s)
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16 27 25.00 -29 24 55.5 GRB 120327A = GRB 120327A
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 40 381 Photometric data for GRB120327A
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 s T-T0 Delta T from the burst event (T-T0) (seconds)
8- 11 I4 s Exp Exposure length (seconds)
13- 17 F5.2 mag mag Magnitude in Band (1)
19- 22 F4.2 mag e_mag Magnitude error (1σ level)
24- 27 A4 --- Band Filter id
29- 40 A12 --- Tel Telescope name
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Note (1): Magnitudes are in the Vega system unless for griz filters that are in
the AB system, and they are all not corrected for Galactic absorption.
Observed bands and number of observations:
uvw1 (1), u (6) v (6), b (7),
g (23), r (10), i (10), z (10),
J (20), H (18), K (15),
B (17), V (42), Rc (92), Ic (97), Y (1), C (6)
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Acknowledgements:
Andrea Meandri, andrea.melandri(at)brera.inaf.it
(End) Patricia Vannier [CDS] 26-Sep-2017