Prompt optical observations of GRB 080330 and GRB 080413A

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Prompt optical observations of GRB 080330 and GRB
080413A
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Background Motivation

• Growing number of early optical afterglow
  observations
• Collective study of temporal behavior
• Panaitescu Vestrand 2008 peak time and peak
  flux correlation
• Growing number of prompt optical observations
• Some show complicated behavior, GRB 08330 and GRB
  080413a
• Multiple components from both internal and
  external shock?
• Start from the better-understood afterglow part

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2008 Mar. 30, 034139.2 22.4 s after the burst
(7.2 s after the GCN notice time) Schaefer
Guver, GCN 7538
2008 Apr. 13, 025439.7 20.4 s after the burst
(6.7 s after the GCN notice time) Rykoff
Rujopakarn, GCN 7593
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2008 Mar. 30, 034139.2 22.4 s after the burst
(7.2 s after the GCN notice time) Schaefer
Guver, GCN 7538
2008 Apr. 13, 025439.7 20.4 s after the burst
(6.7 s after the GCN notice time) Rykoff
Rujopakarn, GCN 7593
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2008 Mar. 30, 034139.2 22.4 s after the burst
(7.2 s after the GCN notice time) Schaefer
Guver, GCN 7538
2008 Apr. 13, 025439.7 20.4 s after the burst
(6.7 s after the GCN notice time) Rykoff
Rujopakarn, GCN 7593
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GRB 080330
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GRB 080330
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GRB 080413a
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GRB 080413a
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Slowly decaying afterglow

• Structured flow viewed off-axis?
• Drowned by prompt emission in X-ray?

Panaitescu Vestrand 2008
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Rising of afterglow

• E?,iso 5.0 x 1051 erg
• ? 2.5 /-0.5
• tpeak 150 s
• G0 200
• (Sari Piran 1999, Molinari et al. 2007)
• Can be classified as XRF
• (Sakamoto et al. 2008, Mao et al. 2008)

• E?,iso 1.7 x 1053 erg
• ? 1.5 /-0.1
• tpeak 30 s
• G0 600

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Prompt optical flash
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Other ROTSE-III events

• E?,iso 3.1 x 1051 erg
• ? 1.9 /-0.1
• tpeak 200 s
• G0 150

• E?,iso 4.2 x 1053 erg
• ? 1.1 /-0.0
• tpeak 40 s
• G0 600

Rykoff 2008 in preparation
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Summary

• Prompt optical component
• Need better sampling
• Complicated by early afterglow
• Better understanding of the afterglow phase will
  help
• Low Lorentz factor events
• Delayed afterglow peak
• Easier to observe the peak and shape of the early
  lightcurve

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Next with ROTSE-III

• More interesting events from Swift (sub-threshold
  triggers)
• GLAST launched
• ROTSE supernova verification project
• Follow-up of IceCube neutrino doublet triggers

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Thank you!
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1.9
2.5
2.1
1.5
2.0
2.1
3.1
1.5