1. Prompt optical observations of GRB 080330 and GRB 080413A

2. 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

3. 2008 Mar. 30, 03:41:39.2 22.4 s after the burst (7.2 s after the GCN notice time) Schaefer & Guver, GCN 7538 2008 Apr. 13, 02:54:39.7 20.4 s after the burst (6.7 s after the GCN notice time) Rykoff & Rujopakarn, GCN 7593

4. 2008 Mar. 30, 03:41:39.2 22.4 s after the burst (7.2 s after the GCN notice time) Schaefer & Guver, GCN 7538 2008 Apr. 13, 02:54:39.7 20.4 s after the burst (6.7 s after the GCN notice time) Rykoff & Rujopakarn, GCN 7593

5. 2008 Mar. 30, 03:41:39.2 22.4 s after the burst (7.2 s after the GCN notice time) Schaefer & Guver, GCN 7538 2008 Apr. 13, 02:54:39.7 20.4 s after the burst (6.7 s after the GCN notice time) Rykoff & Rujopakarn, GCN 7593

6. GRB 080330

8. GRB 080413a

10. Slowly decaying afterglow Structured flow viewed off- axis? Drowned by prompt emission in X-ray? Panaitescu & Vestrand 2008

11. E γ,iso = 5.0 x 10 51 erg γ = 2.5 +/-0.5 t peak ~ 150 s Γ 0 ~ 200 (Sari & Piran 1999, Molinari et al. 2007) Can be classified as XRF (Sakamoto et al. 2008, Mao et al. 2008) E γ,iso = 1.7 x 10 53 erg γ = 1.5 +/-0.1 t peak ~ 30 s Γ 0 ~ 600 Rising of afterglow

12. ‘Prompt’ optical flash

13. Other ROTSE-III events E γ,iso = 3.1 x 10 51 erg γ = 1.9 +/-0.1 t peak ~ 200 s Γ 0 ~ 150 E γ,iso = 4.2 x 10 53 erg γ = 1.1 +/-0.0 t peak ~ 40 s Γ 0 ~ 600 Rykoff 2008 in preparation

14. 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

15. 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

16. Thank you!

17. 2.52.1 1.52.02.1 1.9 3.11.5