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J/ApJ/686/1209      Optical properties of GRB afterglows       (Melandri+, 2008)

The early-time optical properties of gamma-ray burst afterglows. Melandri A., Mundell C.G., Kobayashi S., Guidorzi C., Gomboc A., Steele I.A., Smith R.J., Bersier D., Mottram C.J., Carter D., Bode M.F., O'Brien P.T., Tanvir N.R., Rol E., Chapman R. <Astrophys. J., 686, 1209-1230 (2008)> =2008ApJ...686.1209M
ADC_Keywords: Gamma rays - Photometry, RI Keywords: gamma rays: bursts Abstract: We present a multiwavelength analysis of 63 gamma-ray bursts observed with the world's three largest robotic optical telescopes, the Liverpool and Faulkes Telescopes (North and South). Optical emission was detected for 24 GRBs with brightnesses ranging from R=10 to 22mag in the first 10 minutes after the burst. By comparing optical and X-ray light curves from t=100 to ∼106 seconds, we introduce four main classes, defined by the presence or absence of temporal breaks at optical and/or X-ray wavelengths. While 14/24 GRBs can be modeled with the forward-shock model, explaining the remaining 10 is very challenging in the standard framework even with the introduction of energy injection or an ambient density gradient. Early X-ray afterglows, even segments of light curves described by a power law, may be due to additional emission from the central engine. Thirty-nine GRBs in our sample were not detected and have deep upper limits (R<22mag) at early time. Of these, only 10 were identified by other facilities, primarily at near infrared wavelengths, resulting in a dark burst fraction of ∼50%. Additional emission in the early-time X-ray afterglow due to late-time central engine activity may also explain some dark bursts by making the bursts brighter than expected in the X-ray band compared to the optical band. Description: The sample was observed with the network of three 2m telescopes RoboNet-1.0, formed by the Liverpool Telescope (LT, Canary Islands), the Faulkes Telescope North (FTN; Haleakala, Hawaii), and the Faulkes Telescope South (FTS; Siding Spring, Australia). Up to 2007 September the network robotically reacted to 63 GRBs with 24 optical afterglow detections and 39 upper limits. In this paper the optical photometry of each optical afterglow was performed using Starlink GAIA photometry tools. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 51 224 Optical photometry in the R-band of GRB afterglows
See also: J/ApJ/626/L5 : Photometric observations of GRB 041006 (Stanek+, 2005) J/ApJ/642/L99 : R-band photometry of GRB 060206 (Wozniak+, 2006) J/ApJ/654/L21 : R-band light curves of GRB 060206 and GRB 060210 (Stanek+, 2007) J/ApJ/672/449 : GRB 061126 light curves (Perley+, 2008) : Index of RoboNet Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 11 A11 --- GRB GRB identification (1) 13- 20 F8.3 min Dt Mean time from the burst event 22- 28 F7.3 min Exp Total exposure time 30- 38 A9 --- Filter Filter (SDSS-R or Bessel-R) 40- 45 F6.3 mag Rcmag Rc band magnitude (2) 47- 51 F5.3 mag e_Rcmag 1-σ error in Rcmag
Note (1): References for data published in previous papers, as follows: GRB 050502A = Guidorzi, C., et al. 2005ApJ...630L.121G GRB 050713A = Guetta, D., et al. 2007A&A...461...95G GRB 050730 = Pandey, S. B., et al. 2006A&A...460..415P GRB 051111 = Guidorzi, C., et al. 2007A&A...463..539G GRB 060108 = Oates, S., et al. 2006MNRAS.372..327O GRB 060206 = Monfardini, A., et al. 2006ApJ...648.1125M GRB 060210 = Curran, P., et al. 2007A&A...467.1049C GRB 060927 = Ruiz-Velasco, A. E., et al. 2007ApJ...669....1R GRB 061007 = Mundell, C., et al. 2007ApJ...660..489M GRB 061121 = Page, K., et al. 2007ApJ...663.1125P Note (2): Magnitude are not corrected for Galactic extinction.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Jan-2011
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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