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A.B. Schultz, F. Hamilton, J. Hershey, I. Jordan, M. Kochte (CSC/STScI), G. Henry (TSU), S. Vogt (UCSC), F. Bruhweiler (CUA), A. Storrs (Towson University), H.M. Hart (CSC/JHU), M. Rodrigue (UNR), D.P. Hamilton (UMD), W.F. Welsh (SDSU), D. Taylor (STScI)
We present 40~Hz photometry of the HD~209458b transits obtained with the Fine Guidance Sensors (FGS) onboard the Hubble Space Telescope (HST). HD~209458b is a roaster planet with an orbital period of ~3.5 days yielding a transit time of ~184~min. HST/FGS observations captured portions of the transit ingress and egress. Initial scheduling of the observations was plagued by errors in the phase placement. Even though there are unresolved problems, the FGS observations have appeared to have led to a better confirmation of the mid-transit time for this closely orbiting planet. Analysis of these observations indicates that combining the orbital period reported by Robichon and Arenou (2000) with the mid-transit epoch time (Tc) reported by Brown et al. (2000) for the HST/STIS observations yields the best prediction for the mid transit time. In addition, the FGS photomultipler exhibited a heretofore unknown response to a bright source which required calibration of the data to remove this response. We briefly discuss the scheduling of the observations, the observed response of the FGS, and preliminary analysis and interpretation of the observed transits.
Support for this work provided by NASA through HST/GO grant GO-09171.01-A.
The author(s) of this abstract have provided an email address for comments about the abstract: schultz@stsci.edu