1. New Results from Ground-Based Transit Spectroscopy Observations Jacob Bean Harvard-Smithsonian CfA University of Chicago

2. A new technique for ground-based transit spectroscopy Observation strategy: Time-series spectroscopy with multi-object spectrographs during transits/occultations Simultaneous spectra of target and multiple reference stars during transits – “differential spectroscopy” Wide slits of 12” eliminate slit losses

3. Goals… Reveal the bulk composition of the planet. Resolve the tension between conflicting results. submitted to ApJ and available on astroph New Results for GJ1214b:

4. New spectroscopy in J, H, and K simultaneously (Magellan + MMIRS) New spectroscopy 0.61 – 0.85 μm (VLT + FORS) New narrow-band photometry at 2.09 μm (VLT + HAWKI) Re-analysis of previously reported spectroscopy 0.78 – 1.00 μm (VLT + FORS) submitted to ApJ and available on astroph New Results for GJ1214b:

5. NIR Spectroscopy of GJ1214b 10 7 photons per exposure in K-band  50 ppm on the transit depth GJ1214

6. NIR Spectroscopy of GJ1214b K-band data

7. NIR Spectroscopy of GJ1214b Parameter decorrelation

8. NIR Spectroscopy of GJ1214b

9. 443 ppm per minute 3.4 times the photon noise

10. NIR Spectroscopy of GJ1214b 652 ppm per minute 6.0 times the photon noise

11. NIR Spectroscopy of GJ1214b 608 -- 1060 ppm per minute 2.5 times photon noise

12. Optical Spectroscopy of GJ1214b 504 – 1432 ppm per minute 1.3 times the photon noise

13. Broadband data for GJ1214b

14. Our new measurements

15. Broadband data for GJ1214b Re-analyzed previous measurement

16. Broadband data for GJ1214b Spitzer data (Desert et al. 2011)

17. Broadband data for GJ1214b Croll et al. (2011) measurements

18. Broadband data for GJ1214b No spectral features detected Croll et al. (2011) K-band point inconsistent with MMIRS broadband point at 4.1σ

19. Broadband data for GJ1214b No spectral features detected Croll et al. (2011) K-band point inconsistent with MMIRS broadband point at 4.1σ Solar composition model in chemical equilibrium ruled out at 7.9σ Solar composition model with methane removed is ruled out at 5.2σ

20. K-band spectroscopy for GJ1214b No spectral features detected Confirm results of Crossfield et al. (2011) at lower resolution

21. K-band spectroscopy for GJ1214b No spectral features detected Confirm results of Crossfield et al. (2011) at lower resolution Solar composition model in chemical equilibrium ruled out at 4.3σ Solar composition model with methane removed is consistent

22. No spectral features detected Optical spectroscopy for GJ1214b

23. No spectral features detected Solar composition model in chemical equilibrium ruled out at 6.6σ Solar composition model with methane removed ruled out at 5.2σ Optical spectroscopy for GJ1214b

24. Summary: GJ1214… A remarkably complete ground-based spectrum Spectrum is flat, no deeper transit in the K-band Atmosphere is either >70% water, or has high-altitude clouds/haze Results for other planets with the same technique coming soon

25. Observation schematic spectrum 12” x 30” slits Approx 5’