University of Florida's Exoplanet Tracker (ET) Available for Shared Risk Observing at KPNO 2.1m

Proposals will be accepted in September for shared risk observations with ET during semester 2008A. Interested persons may wish to contact Steve Howell (howell@noao.edu) before submitting proposals in order to discuss how their observational program will match the ET instrument.

NOAO proposals accepted to observe with ET will be performed in a joint queue type program during 1-2 long observing blocks in 2008A. The proposer will be responsible for providing observers to help carry out the block scheduled queue observations at the 2.1-m telescope. The number of total nights available will depend on the community demand and TAC time allocation. Time allocations for ET will not be as usual, as each single observation generally requires a small integration time. Therefore, when you apply, ask for time in nights or fractions thereof, based on the following example. If you are monitoring a single V=8 star in hopes of planet detection and want a measurement each night for 10 nights, your total integration time would approximately be 10 * (15 min + 15 min (overhead)) = 300 min = 1/2 a night (assuming a 10 hr. night). Targets that conform to the general optimized ET observing mode will be batch reduced (by U. Florida) and the radial velocity results distributed to the PI within a few months of the observations.

ET is the prototype of a new high precision radial velocity spectrograph operating at the Kitt Peak 2.1-m telescope. A medium resolution (R~5000) spectrograph, ET covers the wavelength range of 5100-5600A and can produce ultra-high precision radial velocity measurements. The new wrinkle that ET uses to provide such precise measures is that half of the incoming fiber fed beam gets split off and passed through a Michelson interferometer before being recombined. This procedure produces fringe patterns of the absorption lines over the entire spectral range. During the data reduction, these fringe locations are compared with an initial template spectrum and a cross-correlation type procedure outputs the mean velocity for each spectrum.

ET has already confirmed many of the earlier detected exoplanets and even found one of its own - ET1 (see NOAO press release at http://www.noao.edu/outreach/press/pr06/ir0601.html) Details of the instrument and ET's results are given in Ge et al., 2006 (ApJ, 648, 683), van Eyken et al. 2004 (ApJ, 600, L79) and van Eyken et al. 2005 (Protostars and Planets V, page 8579). Additional references can be found on the University of Florida ET Homepage.

The instrumental setup at the 2.1-m and current data reduction procedures are optimized for bright (V ~10th or brighter) solar-like F, G, or K stars. The final velocity precision and required integration time per measurement obtainable by ET (over 7-10 days) is approximately given by the following table. Note that the best use of ET is when high precision velocities are needed over 7-10 days.

Lower precision velocities are measurable as well, but these do not utilize ET at its full potential. The numbers in the table are a rough guide to the results you can expect for a typical ET observing program. Items such as the number and width of absorption lines in ET spectral region will help or hinder the listed values to varying degrees. For example, lines with Vsini =12 km/sec is a pretty hard limit for ET observations. The ET Team does not recommend observation of any stars with Vsini over 12 km/sec.

NOAO is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation.