# Summary of K2 Program GO16011

Title: Revisiting a Successful Campaign: a Second Term Pursuing Transit Timing of K2-discovered Worlds

PI: Fabrycky, Daniel Clark (University of Chicago)
CoIs: Montet, Benjamin T; Agol, Eric; Foreman-Mackey, Daniel; Kruse, Ethan; Luger, Rodrigo

K2 Campaigns 15 and 16 are the first in the K2 mission to have substantial overlap with previous fields. One module in Campaign 15 observations will overlap with Campaign 2, while 30% of the field of Campaign 16 overlaps with Campaign 5. These fields provide unique opportunities beyond those of a typical K2 field. First, the three-year time baseline of observations provide an opportunity to detect transit timing variations (TTVs), which can be used to confirm the planetary nature of transit signals in the K2 data. The observed TTV signal from interacting planets can grow quadratically in time: planetary systems that may have an apparent linear ephemeris in 75 days of data could show significant TTVs over three years. In the cases when both planets transit, this can enable us to infer masses, densities, and eccentricities for both planets in the system. TTVs can also be used to infer the presence of non-transiting planets in the Kepler data by detecting perturbations on observed planets that cannot be explained by other transiting planets in the system. 

The K2 overlap regions also provide the opportunity to detect the smallest planets found by K2. The overlap regions provide 40 square degrees of the sky which will be observed for a total of 150 days, rather than the 75 days of a typical K2 field, enabling the detection of smaller planets that would be below the signal-to-noise threshold of a single K2 campaign. These observations will enable us to detect smaller planets in systems with known planet candidates. Moreover, by re-observing targets from Campaigns 2 and 5 with transit signals below the standard 7.1 sigma threshold for detection, we will have additional opportunities to detect planets smaller than can be observed in any single K2 Campaign.

Additionally, the K2 overlap regions allow us to confirm and precisely measure the periods of long-period planets. Planets with one transit in the K2 data have poorly constrained periods; two planets of near-equal size can masquerade as one planet if only two transits are observed. With a longer time baseline, these planets can be confirmed and their ephemerides precisely measured.

There are 8,362 targets in common between Campaigns 2/5 and 15/16. We will propose to observe a subset of these targets. We will propose all 75 objects of interest detected with our pipeline (Luger et al. 2016, AJ, 152, 100; Kruse et al. in prep), which includes multi-candidate systems with as many as 5 transiting planets. Additionally, we will propose all stars with one or two observed transit events in order to confirm these planets and refine their orbits. We will also propose stars with candidate signals consistent with the presence of small planets which could be detected with an additional 75 days of observations. These observations will enable K2 to detect its smallest planets yet, confirm the planetary nature of any systems with detected TTV signals, and possibly detect non-transiting planets through their interactions with transiting planets.

# Targets requested by this program that have been observed (84)
EPIC ID, RA (J2000) [deg], Dec (J2000) [deg], magnitude, Investigation IDs
211407755, 132.304012, 11.759331, 14.573, GO16011_LC|GO16039_LC|GO16052_LC
211409299, 130.925501, 11.782618, 11.951, GO16009_LC|GO16011_LC|GO16021_LC|GO16065_LC
211411112, 132.612448, 11.808697, 13.405, GO16011_LC|GO16021_LC|GO16031_LC|GO16064_LC
211413752, 133.709545, 11.848265, 13.539, GO16011_LC|GO16015_LC|GO16052_LC|GO16077_LC|GO16101_LC|GO16011_SC|GO16015_SC|GO16101_SC
211419451, 129.449366, 11.932826, 14.068, GO16011_LC|GO16052_LC
211430148, 130.16407, 12.095387, 14.892, GO16011_LC|GO16052_LC|GO16065_LC
211431013, 133.057066, 12.109347, 14.738, GO16011_LC|GO16052_LC|GO16065_LC
211431505, 132.871511, 12.11708, 16.034, GO16011_LC|GO16031_LC|GO16064_LC
211432103, 133.852475, 12.126656, 10.249, GO16009_LC|GO16011_LC|GO16021_LC
211432922, 132.87197, 12.13949, 18.17, GO16011_LC|GO16064_LC
211432946, 132.637296, 12.139833, 14.398, GO16005_LC|GO16011_LC|GO16052_LC|GO16065_LC
211490999, 130.798847, 13.009593, 13.416, GO16011_LC|GO16015_LC|GO16021_LC|GO16077_LC
211491383, 130.155165, 13.014676, 11.785, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16077_LC|GO16011_SC
211492449, 130.938427, 13.030436, 14.277, GO16011_LC|GO16052_LC
211516501, 135.899364, 13.371478, 12.521, GO16009_LC|GO16011_LC|GO16021_LC
211526186, 135.274317, 13.509238, 12.814, GO16009_LC|GO16011_LC|GO16021_LC|GO16065_LC
211529065, 131.266597, 13.549833, 13.431, GO16011_LC|GO16015_LC|GO16021_LC|GO16052_LC|GO16077_LC|GO16101_LC|GO16011_SC|GO16015_SC|GO16101_SC
211541590, 137.176933, 13.724288, 14.336, GO16005_LC|GO16011_LC|GO16052_LC|GO16056_LC
211563123, 131.12904, 14.026493, 12.583, GO16009_LC|GO16011_LC|GO16021_LC|GO16065_LC
211586387, 136.801117, 14.355476, 14.296, GO16011_LC|GO16052_LC|GO16077_LC
211606790, 137.144439, 14.630882, 12.673, GO16009_LC|GO16011_LC|GO16021_LC
211611158, 130.259658, 14.69032, 12.414, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16011_SC
211613886, 135.699628, 14.727976, 12.729, GO16009_LC|GO16011_LC|GO16021_LC|GO16052_LC|GO16065_LC
211682544, 129.682381, 15.680626, 11.407, GO16009_LC|GO16011_LC|GO16015_LC|GO16020_LC|GO16021_LC|GO16101_LC|GO16009_SC|GO16015_SC|GO16101_SC
211705654, 131.273633, 15.989983, 12.059, GO16009_LC|GO16011_LC|GO16020_LC|GO16021_LC|GO16052_LC
211718187, 134.232661, 16.160404, 16.013, GO16011_LC|GO16052_LC
211732801, 129.469627, 16.365739, 10.655, GO16011_LC|GO16021_LC|GO16065_LC
211733267, 130.009413, 16.372406, 12.15, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16052_LC|GO16077_LC|GO16015_SC
211736305, 129.907501, 16.414161, 14.5, GO16011_LC|GO16015_LC|GO16052_LC
211744153, 130.745693, 16.526022, 14.861, GO16004_LC|GO16011_LC|GO16065_LC
211763214, 133.838068, 16.79418, 12.529, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16077_LC
211770390, 131.353503, 16.895773, 12.239, GO16009_LC|GO16011_LC|GO16021_LC|GO16065_LC
211770578, 129.773042, 16.898625, 12.364, GO16011_LC|GO16052_LC
211812160, 133.064644, 17.489027, 13.485, GO16011_LC|GO16021_LC
211814733, 132.667407, 17.524891, 11.971, GO16011_LC|GO16052_LC|GO16077_LC
211816003, 132.62112, 17.542445, 13.654, GO16011_LC|GO16015_LC|GO16021_LC|GO16077_LC
211822797, 130.410365, 17.640005, 14.568, GO16011_LC|GO16015_LC|GO16022_LC|GO16031_LC|GO16052_LC|GO16060_LC|GO16075_LC|GO16101_LC|GO16902_LC|GO16015_SC|GO16075_SC|GO16101_SC
211822953, 131.305863, 17.642097, 16.834, GO16011_LC|GO16065_LC
211825799, 134.371695, 17.68293, 12.877, GO16011_LC|GO16015_LC|GO16052_LC
211834065, 132.548024, 17.799325, 11.634, GO16009_LC|GO16011_LC|GO16021_LC|GO16077_LC
211885185, 131.027432, 18.511049, 12.493, GO16009_LC|GO16011_LC|GO16021_LC|GO16065_LC
211886472, 137.132531, 18.528543, 11.126, GO16011_LC|GO16021_LC|GO16028_LC|GO16077_LC
211896651, 134.141473, 18.67781, 12.724, GO16011_LC|GO16021_LC
211897691, 130.082557, 18.692919, 14.313, GO16011_LC|GO16015_LC|GO16052_LC|GO16077_LC|GO16011_SC
211906259, 131.311027, 18.819358, 12.676, GO16009_LC|GO16011_LC|GO16021_LC|GO16077_LC
211910237, 137.094718, 18.879482, 14.75, GO16011_LC|GO16052_LC|GO16065_LC
211913977, 130.344085, 18.933875, 12.619, GO16009_LC|GO16011_LC|GO16015_LC|GO16020_LC|GO16021_LC|GO16022_LC|GO16031_LC|GO16052_LC|GO16060_LC|GO16075_LC|GO16101_LC|GO16902_LC|GO16015_SC|GO16075_SC|GO16101_SC
211919004, 129.777047, 19.010023, 13.131, GO16011_LC|GO16015_LC|GO16021_LC|GO16052_LC|GO16077_LC
211924657, 130.026777, 19.092879, 15.031, GO16005_LC|GO16011_LC|GO16015_LC|GO16052_LC|GO16077_LC|GO16101_LC|GO16015_SC|GO16101_SC
211925595, 132.95813, 19.10753, 14.466, GO16011_LC|GO16052_LC
211941472, 130.448577, 19.347497, 11.788, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16077_LC
211945201, 136.573975, 19.402252, 10.115, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16025_LC|GO16028_LC|GO16077_LC|GO16015_SC
211946007, 130.664324, 19.414446, 16.57, GO16011_LC|GO16022_LC|GO16031_LC|GO16060_LC|GO16065_LC|GO16075_LC|GO16075_SC
211969807, 129.636756, 19.773829, 15.149, GO16011_LC|GO16015_LC|GO16022_LC|GO16031_LC|GO16052_LC|GO16060_LC|GO16075_LC|GO16077_LC|GO16902_LC|GO16011_SC|GO16015_SC|GO16075_SC
211972837, 129.977592, 19.82192, 13.547, GO16011_LC|GO16021_LC|GO16038_LC|GO16065_LC
211997641, 136.902532, 20.215121, 12.821, GO16009_LC|GO16011_LC|GO16021_LC|GO16065_LC
212006344, 126.476311, 20.359569, 12.466, GO16005_LC|GO16011_LC|GO16015_LC|GO16020_LC|GO16052_LC|GO16077_LC|GO16101_LC|GO16011_SC|GO16015_SC|GO16101_SC
212009150, 126.836469, 20.405804, 16.403, GO16005_LC|GO16011_LC|GO16015_LC|GO16015_SC
212009427, 127.874459, 20.410422, 14.072, GO16011_LC|GO16022_LC|GO16031_LC|GO16052_LC|GO16056_LC|GO16060_LC|GO16075_LC|GO16077_LC|GO16075_SC
212009702, 136.219647, 20.415126, 13.173, GO16011_LC|GO16021_LC|GO16065_LC
212011230, 136.241018, 20.440816, 12.375, GO16011_LC|GO16015_LC|GO16052_LC
212012387, 133.278976, 20.458941, 13.972, GO16011_LC|GO16052_LC|GO16065_LC
212019055, 127.282907, 20.570227, 12.7, GO16011_LC|GO16021_LC|GO16065_LC
212020442, 137.512473, 20.593854, 13.974, GO16011_LC|GO16052_LC|GO16056_LC|GO16065_LC
212021516, 135.786015, 20.61213, 14.54, GO16005_LC|GO16011_LC|GO16052_LC|GO16056_LC
212024647, 127.935241, 20.663782, 10.279, GO16009_LC|GO16011_LC|GO16021_LC|GO16028_LC|GO16065_LC
212037403, 128.178664, 20.87782, 13.231, GO16011_LC|GO16021_LC|GO16065_LC
212069706, 133.42602, 21.450501, 14.41, GO16011_LC|GO16052_LC
212069861, 134.444189, 21.453533, 14.102, GO16005_LC|GO16011_LC|GO16015_LC|GO16052_LC|GO16056_LC|GO16077_LC|GO16015_SC
212072539, 134.202214, 21.502674, 14.874, GO16011_LC|GO16015_LC|GO16052_LC|GO16011_SC
212082682, 133.288485, 21.690459, 14.611, GO16011_LC|GO16052_LC|GO16065_LC
212083250, 132.769917, 21.701352, 11.967, GO16009_LC|GO16011_LC|GO16065_LC
212085740, 127.604274, 21.747054, 13.688, GO16011_LC|GO16021_LC|GO16065_LC
212088059, 132.707863, 21.789122, 14.757, GO16005_LC|GO16011_LC|GO16015_LC|GO16052_LC|GO16077_LC
212096658, 126.753739, 21.956861, 10.21, GO16011_LC|GO16020_LC|GO16052_LC|GO16063_LC|GO16065_LC
212099230, 128.073571, 22.006011, 10.513, GO16009_LC|GO16011_LC|GO16021_LC|GO16077_LC
212109135, 133.801698, 22.201008, 12.452, GO16009_LC|GO16011_LC|GO16021_LC
212110007, 133.310979, 22.218977, 14.245, GO16011_LC|GO16052_LC|GO16065_LC
212110888, 127.57877, 22.235908, 11.441, GO16009_LC|GO16010_LC|GO16011_LC|GO16013_LC|GO16015_LC|GO16028_LC|GO16077_LC|GO16101_LC|GO16902_LC|GO16010_SC|GO16013_SC|GO16015_SC|GO16101_SC
212119244, 128.276901, 22.401849, 12.303, GO16009_LC|GO16011_LC
212154564, 133.641182, 23.13289, 15.105, GO16005_LC|GO16011_LC|GO16015_LC|GO16052_LC|GO16077_LC|GO16011_SC
212163353, 134.212972, 23.330465, 13.539, GO16011_LC|GO16021_LC|GO16052_LC|GO16065_LC
212164470, 129.813631, 23.357481, 12.704, GO16009_LC|GO16011_LC|GO16015_LC|GO16021_LC|GO16077_LC|GO16011_SC
228682450, 132.8380127, 12.1271696, 18.6, GO16011_LC|GO16064_LC