Cover Page/Proposal Summary The XO Planet Finding System Peter R. McCullough Jeff Valenti Chris Johns-Krull Kenneth Janes James N. Heasley We describe a three year plan to continue discovering and characterizing planets that transit bright stars. To date, astronomers have reported more than 25 such transiting planets orbiting bright stars, and their numbers are increasing rapidly (both the number of planets and the number of astronomers studying them). The brightest typically are discovered by oscillating radial velocities, and somewhat fainter ones in much larger numbers are discovered by transits. The XO observatory has recently been expanded to six 0.1-meter diameter cameras, two of which have been operating robotically on Haleakala, Maui, HI since Sep 2003 and with which we have discovered five transiting planets. We evaluate transiting-planet candidates produced by the XO survey cameras with precise photometric observations, which significantly reduces the number of candidates we observe spectroscopically. For the follow-up photometry, we have recruited a global network of privately-funded and operated observatories, in addition to our team's institutional access to observatories in Hawaii, Texas, and Arizona. Dozens of candidates per year will be scrutinized with moderate-precision (∼1 km/s) radial velocity observations and a few of those will be confirmed to be planets with (∼10 m/s) precision. We will pursue precise photometric and spectroscopic follow up observations of transiting planets discovered by XO, HAT, WASP, etc. Our team has prior experience with scintillation- limited ground-based photometry, time-series photometry with SST IRAC, spectrophotometry with HST instruments NICMOS, STIS, ACS, and WFC3 (in ground-tests), and is developing spectroscopic analysis techniques to improve the precision of radial velocities from Keck and HET. We also propose to increase the number of amateur astronomers observing such transits and to motivate their training to continuously improve their observational techniques, which in some cases already rival that of professionals. For the period 2003-2009, the XO team has been supported by two NASA Origins awards. Follow-up observations with HST and SST have been supported by those NASA programs. The tripling of XO's cameras and associated electronics has been supported by peer-reviewed competition for institutional funds of the STScI Director. 1 Contents 1 Objectives and Significance 5 1.1 Scientific Objectives: find more transiting planets . 5 1.2 Brighter is Better . 5 1.3 Significance of Transits: more than P, m sin i, and e . 5 1.4 Longer periods: satellites as habitable worlds . 7 1.5 Multiple planets: spectroscopic and photometric searches . 7 1.6 Devote more spectroscopy to some Duds . 8 1.7 Better characterization: improved photometry and spectroscopy . 8 1.8 Additional Science Enabled . 8 2 Technical Approach and Methodology 9 2.1 Summary of XO Operations and Results, 2002-2008 . 9 2.2 Comparison to other Searches for TEPs . 10 2.3 How to find longer-period TEPs . 11 2.4 How to find multi-TEP systems . 14 2.5 Strategy for Followup . 15 2.6 Comparison to other Searches for TEPs . 15 3 Impact of Proposed Work 16 4 Relevance to other NASA Programs and Missions 16 5 Management Plan 17 6 Facilities, Equipment and Other Resources 24 6.1 The Robotic Camera . 24 6.2 The Extended Team of Amateur Astronomers . 24 6.3 Space Telescope Science Institute (McCullough & Valenti) . 24 6.4 University of Hawaii (Heasley) . 24 6.5 Boston University Astronomy Department and Institute for Astrophysical Re- search(Janes) . 24 6.6 Rice University (Johns-Krull) . 25 7 Vitae 27 8 Current and Pending Support 32 8.1 Peter McCullough . 32 8.2 Jeff Valenti . 32 8.3 Ken Janes . 32 8.4 James Heasley . 32 2 9 Letters of Commitment 33 9.1 Peter McCullough . 33 9.2 Jeff Valenti . 33 9.3 Ken Janes . 33 9.4 James Heasley . 34 9.5 You-Hua Chu . 35 9.6 Debra Fischer . 36 9.7 Ron Gilliland . 37 9.8 Frank Summers . 37 9.9 ET member 1, Tonny Vanmunster . 38 9.10 ET member 2, Paul Howell . 39 9.11 ET member 3, Ron Bissinger . 39 9.12 ET member 4, Bruce Gary . 40 10 Budget Narrative 41 10.1 Personnel . 41 10.2 Supplies . 41 10.3 Supplies . 41 10.4 Travel Costs . 41 10.5 Publication Costs . 42 10.6 Indirect Costs . 42 3 Summary of Personnel and Work Efforts We request salary support for three persons, Peter McCullough, his data analyst, and his post doctoral researcher. Their work effort and schedule are as follows. In order to apportion costs appropriately, we assume that their additional efforts to study transiting hot Jupiters with HST, Warm Spitzer if it is funded, etc will be funded with grants accompanying observing time on those observatories. That is why, e.g., this grant allocates 1.5 years, not 3 years, to the Postdoc. Name of PI/Co-I FTE1 devoted to project Years Period McCullough 25% 3 03/15/2009-3/15/2012 Data Analyst 37.5% 3 09/01/2009-3/01/2012 Postdoc 100% 1.5 09/01/2009-3/01/2012 Valenti * 3 03/15/2009-3/15/2012 Janes * 3 03/15/2009-3/15/2012 Johns-Krull * 3 03/15/2009-3/15/2012 Heasley * 3 03/15/2009-3/15/2012 1 FTE = Full Time Equivalent * Valenti, Janes, Johns-Krull, and Heasley will each contribute approximately 0.05 FTE per year at no cost to this award. (None of them are civil servants { they can work for free without violating full cost accounting practices.) Origins will have to stretch to pay for McCullough, DA, and PD for 3 years. We need to decide how to economize. One thought is to not include a PD in this, but rely on Valenti, Janes, Johns-Krull, Heasley to write ApJ papers. I anticipate that XO, HAT, WASP will begin to publish discoveries in groups instead of one at a time. This is natural if the final RV follow up occurs on a traditionally allocated telescope like Keck as compared to the queued HET. Also, one needs multiple planets in a year; if XO's output triples, then we can anticipate 6 planets per year, but we may choose to throttle back XO's rate of 3-day planets in order to increase its rate of 10-day planets by pointing all cameras in the same direction. 4 1 Objectives and Significance This proposal describes continued progress and future goals of the XO Project, one of the leading teams discovering and characterizing Transiting Extrasolar Planets, or TEPs. 1.1 Scientific Objectives: find more transiting planets 1.2 Brighter is Better The mantra \Brighter is Better" largely has been assimilated into the community studying TEPs. For studies of TEPs, brighter stars are better because they tend to allow a larger variety of possible follow-up observations. Very precise work is photon-limited almost by definition, but in detail there are trades even for this simple principle. For space-based follow up, e.g. with HST NICMOS or SST IRAC, in the stellar magnitude range 8 < V < 12, overheads associated with reading out the detector before saturation tend to make observations of stars at the fainter end (V=12) record much more than 40-times-fewer photons than those collected from stars at the brighter end (V=8). For instance, in a recent HST NICMOS proposal1, to detect water vapor in the atmosphere of a TEP, we showed that a single transit of XO-4b (V=10.8) should produce the same S/N ratio as that of HD 189733b (V=8), after one accounts for readout and buffer dump overheads, the duration of the transits, and the occultation of the Earth (for HD 189733b but not XO-4b). For space-based and ground-based observations, stars near the fainter end (10 < V < 12) tend to have more comparison stars that also are closer in angle and more similar in color to the target star than the 8 < V < 9 stars. For all stars in the range 8 < V < 12, ground-based observations in broad spectral bandpasses are scintillation limited, so the fainter stars and the brighter stars often give similar S/N ratios. Example light curves are in Figure ??. In Section XX, we describe a technique that should permit us to cancel scintillation for observations of some TEPs with the world's largest ground-based telescopes, preparing the community for the JWST era of photon-limited2 large-aperture observations of TEPs and the scientific opportunities they provide. We need to reconcile the following leftover from an old proposal with our current belief that these stars should be scintillation limited in broad bandpasses. Also, KeplerCam (Holman, XO- 1b) claims shot noise to be dominant - maybe due to poor throughput at z band? With a 0.3-m telescope and a goal of 1 millimag photometry on V=12 stars, an exposure time of 5 minutes is required with no filter, or 15 minutes with a broadband filter such as V, R, or I. For such exposures, scintillation is less than shot noise, except for airmass ∼> 2. 1.3 Significance of Transits: more than P, m sin i, and e Greg Laughlin has noted that 2008 may be the first year that more planets are discovered by transits than by radial velocities, and Kepler has not even been launched yet.3 With hundreds 1McCullough is the P.I. of this GO proposal under review by the HST TAC, May 2008. 2Photon-limited means limited by the Poisson statistics of photons, not by scintillation or other sources of systematic noise that in principle can be removed by calibration.