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NICMOS spectroscopy of HD 189733b

Published online by Cambridge University Press:  10 November 2011

Mark R. Swain
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove, Pasadena, California, 91109, United States email: Mark.R.Swain@jpl.nasa.gov
Pieter Deroo
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove, Pasadena, California, 91109, United States email: Mark.R.Swain@jpl.nasa.gov
Gautam Vasisht
Affiliation:
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove, Pasadena, California, 91109, United States email: Mark.R.Swain@jpl.nasa.gov
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Abstract

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Spectral features corresponding to methane and water opacity were reported based on transmission spectroscopy of HD 189733b with Hubble/NICMOS. Recently, these data, and a similar data set for XO-1b, have been reexamined in Gibson et al. (2010), who claim they cannot reliably reproduce prior results. We examine the methods used by the Gibson team and identify two specific issues that could act to increase the formal uncertainties and to create instability in the minimization process. This would also be consistent with the GPA10 finding that they could not identify a way to select among the several instrument models they constructed. In the case of XO-1b, the Gibson team significantly changed the way in which the instrument model is defined (both with respect to the three approaches they used for HD 189733b, and the approach used by previous authors); this change, which omits the effect of the spectrum position on the detector, makes direct intercomparison of results difficult. In the experience of our group, the position of the spectrum on the detector is an important element of the instrument model because of the significant residual structure in the NICMOS spectral flat field. The approach of changing instrument models significantly complicates understanding the data reduction process and interpreting the results. Our team favors establishing a consistent method of handling NICMOS instrument systematic errors and applying it uniformly to data sets.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Burke, C. et al. 2010, ApJ, 719, 1796CrossRefGoogle Scholar
Charbonneau, D., Brown, T. M., & Noyes, R. W., Gilliland, R. L. 2002, ApJ, 568, 377CrossRefGoogle Scholar
Gibson, N. P., Pont, F., & Aigrain, S. 2011, MNRAS, 411, 2199CrossRefGoogle Scholar
Grillmair, C. J., et al. 2008, Nature, 456, 767CrossRefGoogle Scholar
Jurgenson, C., et al. 2010, SPIE, 7735, 43JGoogle Scholar
Pont, F., Knutson, H., Gilliland, R. L., Moutou, C., & Charbonneau, D. 2008, MNRAS, 385, 109CrossRefGoogle Scholar
Pont, F., Gilliland, R. L., Knutson, H., Holman, M., & Charbonneau, D. 2009, MNRAS, 393, 6CrossRefGoogle Scholar
Redfield, S., Endl, M., Cochran, W. D., & Koesterke, L. 2008, ApJ (Letters), 673, 87CrossRefGoogle Scholar
Swain, M. R., Vasisht, G., & Tinetti, G. 2008, Nature, 452, 329CrossRefGoogle Scholar
Swain, M. R., Vasisht, G., Tinetti, G., Bouwman, J., Chen, P., Yung, Y., Deming, D., & Deroo, P. 2009a, ApJ (Letters), 690, 114CrossRefGoogle Scholar
Swain, M. R., et al. 2009b, ApJ (Letters), 704, 1616CrossRefGoogle Scholar
Swain, M. R., et al. 2010, Nature, 463, 637CrossRefGoogle Scholar
Snellen, I. A. G., Albrecht, S., De Mooij, E. J. W. & Le Poole, R. S. 2008, A&A, 483, 375Google Scholar
Snellen, I. A. G., de Kok, R. J., De Mooij, E. J. W., & Albrecht, S. 2010, Nature, 465, 1049CrossRefGoogle Scholar
Thatte, A., Deroo, P., & Swain, M. R. 2010, A&A, 523, 35Google Scholar
Tinetti, G., Deroo, P., Swain, M. R., Griffith, C. A., Vasisht, G., Brown, L. R., Burke, C., & McCullough, P. 2010, ApJ (Letters), 712, 139CrossRefGoogle Scholar