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AAVSO Special Notice #1 (December 8, 2005) Exoplanet Transit Campaign for Southern Hemisphere
Dr. Greg Laughlin (UCO Lick Observatory/Transitsearch.org) and Dr. David Blank (James Cook University) are conducting a photometric monitoring campaign for exoplanet transits of HD 13445. The windows for possible transit are: December 11 20:51 - December 12 05:00 (UT) December 27 14:58 - December 27 23:36 (UT) HD 1334 is located at RA 02:10:14.4 and Dec. -50:50:0.5 (J2000). The possible transit times are estimates so observing before and after the windows is encouraged. HD 13445 is bright at V=6.17 so observing will be a challenge. For help, consult the Transitsearch Mailing List available at www.transitsearch.org. Also, advice is available in the bright star photometry section of the AAVSO CCD Observing Manual at the URL below: http://www.aavso.org/observing/programs/ccd/manual/4.shtml#7 If there is a transit, the estimated amplitude is 0.021 magnitudes and estimated duration is 273 minutes. A chart is not planned at this time. The campaign is being coordinated through the Transitsearch Mailing List. A circular announcing the campaign is available in the News section of their web site at the previously mentioned URL. The following background is written by Dr. Blank and reprinted from the circular with permission: "HD 13445 is a nearby (d=11 pc) K1 V star accompanied by a planet that is at least four times as massive as Jupiter. Seagroves et al. (2003) classify HD 13445b as an intermediate period exoplanet since the orbital period of 15.8 days is longer than those of the so-called hot Jupiters . Intermediate period planets will have significantly cooler atmospheres than the hot jupiters, and are expected to be characterized by very different atmospheric chemistry and dynamics. To date, however, there have been no observed transits of intermediate period exoplanets. The discovery of such a transit would be valuable because it would give us the basic physical properties (radius, mass and density) of a giant planet whose estimated temperature of T ~ 600 K is in a completely unexplored regime. Furthermore, the bright magnitude of the parent star would make HD 13445 b an ideal candidate for high-resolution follow-up. Getting these basic properties would give information about the internal structure of the planet and possibly its formation. Spectroscopically, the planet is likely a member of the yet-unobserved Y dwarf class, in which the spectral features are expected to be dominated by Ammonia lines... "It will probably take observations over at least two or three windows before one can be sure whether the planet is transiting or not." Observations should be submitted to the AAVSO as either "HD 13445" or "0206-51". They will be compiled and submitted to Dr. Laughlin and Dr. Blank. Good luck! References Seagroves, S., Harker, J., Laughlin, G., Lacy, J., and Castellano, T. P. 2003, PASP, 115, 1355 This special notice was written by A. Price. -------------------------------------------------------------------- To unsubscribe from the AAVSO Special Notice electronic announcements reply to this e-mail with "unsubscribe" in the Subject line. Archives of past Special Notices are available at: http://www.aavso.org/publications/specialnotice/

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