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S. B. Howell, M. Everett, D. R. Davis, S. J. Weidenschilling (Planetary Science Institute), C. H. McGruder, III, R. Gelderman (Western Kentucky University)
We describe a new program for the photometric detection of extrasolar planets using the 1.3 m telescope on Kitt Peak, which will be operated by a consortium of universities headed by Western Kentucky Univ. and including South Carolina State Univ., Planetary Science Institute, Boston Univ., and UC-Berkeley (SSL). This approach will complement the existing, highly successful, spectroscopic searches. The theory of photometric transit detection has been discussed by a number of authors (e.g. Borucki & Summers 1984; Howell & Merline 1995; Howell et al. 1996) and shown to be well within the capabilities of both photomultiplier and CCD observations. The first photometric transit detection was recently accomplished for the spectroscopically discovered planet orbiting HD209458 (Henry et al. 2000).
The detection of extrasolar planet transits requires high photometric precision rather than accuracy. The necessary photometric precision to detect Jupiter-, Neptune-, and Earth-sized planets in orbit around F-M dwarfs is 1%, 0.1% and 0.00001%, respectively. The required precision to observe transits by Jupiter-sized extrasolar planets is easily obtained with modern CCD detectors and the differential ensemble photometric techniques pioneered by Howell et al. (1988). The use of such a technique for ultra-high precision photometry has been described in numerous papers (Charbonneau et al. 2000, Howell 2000, plus many others). Everett and Howell recently used the Kitt Peak NOAO 0.9 m telescope with the wide-field MOSAIC camera to search for extrasolar planet transits. During this run, they achieved a photometric precision of 0.024% for this dataset. With the 1.3 m telescope, we expect to reach a photometric precision of ~0.01% (10-4 mag).
Our consortium has recently begun to refurbish and automate the 1.3 m telescope, which will be known as the Remote-Controlled Telescope (RCT). The primary instrument will be a CCD camera with a SITe 2048 x 2048 CCD having pixel well depths of 363,000 electrons, read noise of 5 electrons, and quantum efficiency of 80% between 4000 and 7000 Angstroms. The camera will be able to image a 20 x 20 arcmin field of view with 0.6 arcsec/pixel to provide well-sampled PSFs. About 40% of the time on the RCT will be devoted to the search for extrasolar planets. Search observations are expected to begin in mid-2001.
References: Borucki & Summers 1984, Icarus 58:121; Charbonneau et al. 2000, ApJ 529:L45; Henry et al. 2000, ApJ 529:L41; Howell 2000, Handbook of CCD Astronomy, Cambridge Univ. Press; Howell et al. 1996, AJ 112:1302; Howell & Merline 1995, Exp. Ast. 6:163; Howell et al. 1988, AJ 95:247.