Zoekopdracht:
journal id: "astronomyxandxastrophysics"
| Auteurs | J. Gorosabel, E. Rol, S. Covino, A.J. Castro-Tirado, J.M. Castro Cerón, D. Lazzati, J. Hjorth, D. Malesani, R.A.M.J. Wijers | | Titel | GRB 020813: Polarization in the case of a smooth optical decay |
| Tijdschrift | Astronomy and astrophysics |
| Jaargang | 422 |
| Jaar | 2004 |
| Pagina's | 113-119 |
| ISSN | 00046361 |
| Faculteit | Faculteit der Natuurwetenschappen, Wiskunde en Informatica |
| Instituut/afd. | FNWI: Astronomical Institute Anton Pannekoek (IAP) |
| Trefwoorden | Gamma ray bursts; Photometric techniques |
| Samenvatting | We present the results of a VLT polarimetric monitoring campaign of the GRB 020813 optical afterglow carried out in three nights, from 0.88 to 4.20 days after the gamma-ray event. The mean values of the degree of linear polarization (P) and its position angle (è) resulting from our campaign are < P>=1.18 ± 0.10 % and < è> = 148.7° ± 2.3°, after correcting for Galactic interstellar polarization. Our VLT data set is most naturally described by a constant degree of linear polarization and position angle, nonetheless a slow è evolution cannot be entirely ruled out by our data. The VLT monitoring campaign did not reveal either a significant è rotation respect to the Keck spectropolarimetric observations performed ~0.25 days after the GRB (Barth et al. cite{Bart03a}). However, < P> is a factor of two lower than the polarization degree measured from Keck. Additionally, the VLT polarization data allowed us to construct an accurate V-band light curve. The V-band photometric data revealed a smooth light curve with a break located between the last Keck and our first VLT polarimetric measurement, 0.33 < tbreak, V < 0.88 days after the GRB. The typical magnitude fluctuations of the VLT V-band lightcurve are 0.003 mag, 0.010 mag and 0.016 mag for our three observing nights, respectively. We speculate that the stability of è might be related to the smoothness of the light curve. Based on observations collected at the European Southern Observatory, Cerro Paranal (Chile), ESO programmes 69.D-0461(A) and 69.D-0701(A). |
| Opmerkingen | cop. 2004 EDP Sciences |
| Soort document | Artikel |
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