Transiting Exoplanet Monitoring Project (TEMP). I. Refined System Parameters and Transit Timing Variations of HAT-P-29b
Songhu Wang Xian-Yu Wang Yong-Hao Wang Hui-Gen Liu Tobias C. Hinse Jason Eastman Daniel Bayliss Yasunori Hori Shao-Ming Hu Kai Li Jinzhong Liu Norio Narita Xiyan Peng R. A. Wittenmyer Zhen-Yu Wu Hui Zhang Xiaojia Zhang Haibin Zhao Ji-Lin Zhou George Zhou Xu Zhou Gregory Laughlin




  

Songhu Wang
song-hu.wang@yale.edu


Department of Astronomy, Yale University, New Haven, CT 06511, USA
51 Pegasi b Fellow


Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
University of Chinese Academy of Sciences, Beijing, 100049, China


Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
University of Chinese Academy of Sciences, Beijing, 100049, China


School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 210093, China


Korea Astronomy & Space Science Institute, 305-348 Daejeon, Republic of Korea


Harvard-Smithsonian Center for Astrophysics, Garden Street, Cambridge, MA 02138 USA


Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK


National Astronomical Observatory of Japan, NINS, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan


Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai 264209, China


Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai 264209, China


Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, China


National Astronomical Observatory of Japan, NINS, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Astrobiology Center, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, Japan
Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan



Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China


University of Southern Queensland, Computational Engineering and Science Research Centre, Toowoomba, Queensland 4350, Australia


Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China
University of Chinese Academy of Sciences, Beijing, 100049, China


School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 210093, China


Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong 


Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China


School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics in Ministry of Education, Nanjing University, Nanjing 210093, China


Harvard-Smithsonian Center for Astrophysics, Garden Street, Cambridge, MA 02138 USA


Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China


Department of Astronomy, Yale University, New Haven, CT 06511, USA





 
 We report the photometry of six transits of the hot Jupiter HAT-P-29b obtained from 2013 October to 2015 January. We analyze the new light curves, in combination with the published photometric, and Doppler velocimetric, and spectroscopic measurements, finding an updated orbital ephemeris for the HAT-P-29 system, T_ C[0]= 2456170.5494(15) [BJD_TDB] and P=5.723390(13)   days. It is 17.63  s (4.0 σ) longer than the previously published value, amounting to errors exceeding 2.5 hrs at the time of writing (on UTC 2018 June 1). The measured transit mid-times for HAT-P-29b show no compelling evidence of timing anomalies from a linear model, which rules out the presence of a perturbers with masses greater than 0.6, 0.7, 0.5, and 0.4  M_⊕ near the 1:2, 2:3, 3:2, and 2:1 resonances with HAT-P-29b, respectively. 
 






§ INTRODUCTION


High-precision photometric follow-up observations permit the refined determination of physical properties (especially the radii) of known transiting exoplanets (e.g., ). An accumulation  of these data provide new insights into the distribution of planetary interior structures, formation and evolution processes.

Follow-up observations are also required to update and maintain planetary orbital ephemerides <cit.>, which are 
needed in order to confidently schedule in-transit follow-up observations (e.g., Rossiter-Mclaughlin effect measurements: , or atmospheric transmission spectra observations: ). 



Moreover, high-precision photometric follow-up observations, and by extension, accurate measurements of transit timing variations (TTVs) of known hot Jupiters, offer a powerful tool for the detection of hot Jupiter companion planets with masses comparable to Earth's <cit.>. It will provide a key zeroth-order test of the competing mechanisms of hot Jupiter formation <cit.>.

Photometric follow-up observations are also often needed before definitive TTV-determined masses can be achieved for K2 (and in the near future, TESS) planets <cit.>. The K2 <cit.> and upcoming TESS <cit.> missions only monitor each target field for ∼80 and ∼27 days, respectively. The timescales associated with TTV signals, however, are typically several years <cit.>. 

Finally, high-precision multi-band transit photometry is also a powerful diagnostic tool for exploring the atmospheric properties of close-in planets, notably, the atmospheric compositions and meteorological conditions associated with clouds and hazes (e.g., ). 


llccccc

0pt
 TEMP Network Telescopes
Telescope       Observatory        Longitude     Latitude      Aperture       FOV       Pixel Scale  


200-Inch Telescope/WIRC      Palomar Observatory     116^∘51'54”W     33^∘21'21”N      5m     8.7'×8.7'     0.25 
  
NAOC-Schmidt Telescope      National Observatory of China     117^∘34'30”E     40^∘23'39”N     0.6/0.9m     94'×94'     1.37”/pixel 
  
NAOC-60cm Telescope      National Observatory of China     117^∘34'30”E     40^∘23'39”N     0.6m     17'×17'     1.95”/pixel 
  
Weihai-1m Telescope      Shandong University/Weihai Observatory     122^∘02'58”E     37^∘32'09”N      1.0m     12'×12'     0.35”/pixel 
  
Tido Telescope       Nanjing University/Ali Observatory     80^∘05'57.14”E      32^∘29'46.26”N      1,0m      3^∘× 3^∘     1.76”/pixel 
  
Nanshan-1m Telescope       Xinjiang Observatory     87^∘10'30”E      43^∘28'24.66”N     1.0m     1.3^∘×1.3^∘      1.14”/pixel 
  
Near Earth Objects Telescope       Purple Mountain Observatory     118^∘28'E     32^∘44'N      1.2m     3.0^∘×3.0^∘     1.03”/pixel 
  
Minerva-Australia Telescope       USQ/Mt Kent Observatory     151^∘51'19.5”E      270^∘47'52.3”E     0.7m      21'×21'      0.6”/pixel  
 
BOAO Telescope     Bohyunsan Optical Astronomy Observatory     128^∘ 58' 35”  E     36^∘ 09' 53”  N     1.8m     14.6' × 14.6'     0.21”/pixel 

SOAO Telescope     Sobaeksan Optical Astronomy Observatory     128^∘ 27' 25”  E     36^∘ 56' 13”  N     0.6m     17.6' × 17.6'     0.52”/pixel 

CbNUO Telescope     Chungbuk National University Observatory     127^∘ 28' 31”  E     36^∘ 46' 53”  N     0.6m     72' × 72'     1.05”/pixel 

LOAO-1m Telescope     Mt. Lemmon Optical Astronomy Observatory     249^∘ 12' 41”  E     32^∘ 26' 32”  N     1.0     22.2' × 22.2'     0.64”/pixel  



For these reasons, we have initiated the Transiting Exoplanet Monitoring Project (TEMP) to gather long-term, high-quality photometry of exoplanetary transits with 1-meter-class ground-based telescopes (see Figure <ref> and Table <ref> for the TEMP network locations and telescopes). The scientific goals are:
 
 

  * Identify and characterize undetected planets interleaved among known transiting planets via TTVs.


  * Refine the orbital and physical parameters of the known transiting planets discovered with ground-based photometric surveys, which usually only received a handful of photometric follow-up observations.


  * Make definitive estimates of planetary masses in multi-transiting systems discovered with K2 and TESS via TTVs.


  * Characterize exoplanetary  compositions and atmospheric properties with multi-band photometry.


To date, ∼ 300 light curves of about 60 transiting exoplanets have been obtained through the TEMP network (, In prep.). The light curves (see Figure <ref> for examples) have a typical photometric precision ranging from 1 to 2 mmag, depending on weather and the stellar magnitude. In the best cases, sub-mmag photometric precision has been achieved. 

Here, we present one of our first scientific results, namely a refined characterization of the HAT-P-29 planetary system.

The transiting hot Jupiter HAT-P-29b was discovered by <cit.> under the auspices of the HATNet project. Although extended Doppler velocity monitoring shows evidence for the existence of a distant outer companion in the system <cit.>, HAT-P-29b is otherwise a comparatively normal transiting exoplanetary system consisting of a 1.2  M_⊙ star circled by a 0.78  M_JUP planet with an orbital period of 5.72  days. The relatively long period introduces challenges for ground-based follow-up using meter-class telescopes. The photometric characterization of HAT-P-29b in the discovery work rested on only two partial follow-up transit light curves, and the discovery light curve which is of limited quality. Moreover, four additional Doppler velocimetric measurements (there are eight in discovery paper) were obtained by <cit.> for this system. <cit.> also improved the spectroscopic properties of the host star for this system.

Here, we report the first photometric transit follow-up of HAT-P-29b since the discovery work, covering six transits (only two of these are complete, however). This new material, coupled with all archival photometric <cit.>, spectroscopic <cit.>, and Doppler velocimetric data <cit.>, permits refinement of the planetary orbital and physical properties. By analyzing the transit mid-times of all available follow-up light curves (six from this work, and two from ), we effectively constrain the parameter space of the potential nearby perturbers.

We proceed in the following manner: 
In 2, we describe the new photometric observations and their reduction.
3 details the technique we used to estimate the system parameters.
4 discusses our results and some implications.
A brief summary of this work is presented in 5.



§ OBSERVATION AND DATA REDUCTION



ccccccccc

0pt
Log of Observations

Date       Time        Telescope     Filter      Number of exposures       Exposure time       Airmass       Moon Phase      Scattera

(UTC)       (UTC)                                                      (second)                                    


2013 Nov 14       13:34:55-19:32:22       NAOC-Schmidt       R         190        80        1.02-1.52      0.91     0.0023 

2013 Dec 07       11:31:53-16:18:58       NAOC-Schmidt       R         108        100       1.02-1.19      0.29    0.0019 

2013 Dec 30       09:56:14-15:59:01       NAOC-Schmidt       R         216        60        1.02-1.39       0.05     0.0019 

2014 Feb 08       10:49:06-13:51:03       NAOC-Schmidt       R         109        60        1.07-1.50       0.68    0.0026 

2014 Nov 21       14:00:18-18:55:51       NAOC-Schmidt       R         332        35         1.02-1.46      0.01     0.0037 

2015 Jan  06       10:17:43-15:25:02       Weihai-1  m                                 V         230         60         1.02-1.33      0.98     0.0023 

aScatter represents the RMS of the residuals from the best-fitting transit model. 






Five transits of HAT-P-29b, between 2013 October and 2014 November were observed in a Cousins R filter with the 60/90  cm Schmidt telescope at Xinglong Station (117^∘ 34'30”E, 40^∘ 23'39”N) of the National Astronomical Observatories of China (NAOC). 
The telescope is equipped with a 4 K× 4 K CCD that gives a 94' × 94' field of view (FOV). A 512 × 512 pixel (approximately 11.7' × 11.7') subframe was used to reduce the readout time from 93 to 4  s, significantly increasing the duty-cycle of the observations. For our observations, the images were not binned, giving a pixel scale of 1.38”  pixel ^-1.
For full details of this telescope, we refer the reader to <cit.>.



A sixth transit, obtained on UTC 2015 January 6, was observed through a Johnson V filter using the 1-m telescope operated at Weihai Observatory (122^∘ 02'58.6”E, 37^∘ 32'09.3”N) of Shandong University, China. The telescope has a 2 K× 2 K  CCD with a 12' × 12' FOV. No windowing or binning was used, resulting in a pixel scale of 0.35”  pixel ^-1, and a readout/reset time between exposures of 15 s. For further instrumental details of this telescope, see <cit.>. 

To maintain a high signal-to-noise ratio (SNR>1000) for both the target and comparison stars, exposure times were varied from 35 to 100  s, depending on atmospheric conditions. Nevertheless, exposure times were not changed during the ingress or egress phases to avoid adversely affecting the transit timing. The mid-exposure time is recorded in the image header, and is synchronized with the USNO master clock time[http://tycho.usno.navy.mil/.] at the beginning of each night. The intrinsic error for all recorded times in the image headers is estimated to be less than 1s. 
The recorded time stamps are converted from JD_UTC to BJD_TDB using the techniques of <cit.>.
A summary of our observations is given in Table <ref>.


cccc
0pt
Photometry of HAT-P-29

BJD_TDBa     Relative Flux     Uncertainty      Filter 

2456611.083603       0.9995        0.0023        R 

      2456611.084783       0.9965        0.0023        R 

      2456611.085976       0.9996        0.0023        R

      2456611.087168       1.0002        0.0023        R 

      2456611.088348       1.0004        0.0023       R 

      2456611.089540       1.0019        0.0023       R 
 
      2456611.090721       0.9997        0.0023       R

      ...                  ...           ...          ... 

a The time stamps are based on the Barycentric Julian Date (BJD) in Barycentric Dynamical Time (TDB). 
The timings throughout the paper are placed on the BJD_TDB time system.



All data are bias-corrected and flat-fielded using standard routines.
Aperture photometry is then performed using SExtractor <cit.>.
The final differential light curves are obtained from weighted ensemble photometry. 
The aperture sizes and the choice of comparison stars are optimized to minimize the out-of-transit root-mean-square (RMS) scatter.
The resulting light curves are given in Table <ref>, and are compared in Figures <ref> and <ref> to the best-fitting model[Table <ref> is available in its entirety on http://casdc.china-vo.org/archive/TEMP/HAT-P-29/.]. The scatter of the residuals from the best-fitting model in these light curves varies from 1.9 to 3.7mmag.



§ LIGHT CURVE ANALYSIS


To re-estimate the system parameters of HAT-P-29, we performed two global fittings, one in which we only used follow-up light curves (six from this work, and two from ), the second included the HATNet discovery photometry. We simultaneously model photometric data, together with high-precision RV measurements  <cit.> acquired with Keck/HIRES using EXOFAST <cit.>.




EXOFAST fits each data set independently to determine an error scaling and preliminary best fit, then uses the Differential Evolution Markov Chain Monte Carlo (DE-MCMC; ) to refine the best global fit (including all data sets, the  relation to determine the stellar parameters, and a loose prior on the limb darkening from ) and characterizes the uncertainties. We allow the eccentricity to float, although the fitted eccentricity is consistent with zero. The chains are run until well mixed, as described in <cit.> and the results are summarized in Table <ref>.

We imposed priors on the all transit and RV parameters – the orbital period (P) of 5.723186 ± 0.000049  days,  the planet-to-star radius ratio (R_ P/R_∗) of 0.0927 ± 0.0028, the scaled semimajor axis (a/R_∗) of 11.70_-0.97^+0.71, the inclination (i) of 87.1^∘ _-0.7^∘^+0.5^∘,  the eccentricity (e) of 0.095 ± 0.047, the argument of periastron (ω_*) of 169^∘± 30^∘, the RV semi-amplitude (K) of 78.3  m s^-1± 5.9   m s^-1, – from discovery paper <cit.>. We also set priors on the stellar spectroscopic parameters – the stellar effective temperature (T_ eff) of 6086± 69   K, the surface gravity (log g) of 4.34 ± 0.06, metallicity ([Fe/H]) of 0.14 ± 0.08 – from <cit.>. Moreover, we adopted wavelength dependent limb-darkening coefficients 
μ_1,R=0.323, and μ_2,R=0.305 for the Cousins R bandpass, 
μ_1,V=0.412, and μ_2,V=0.288 for the Johnson-Morgan V bandpass,
μ_1,r=0.344, and μ_2,r=0.306 for the Sloan r bandpass
based on the values  tabulated in <cit.> for the stellar parameters from <cit.>.








§ RESULT AND DISCUSSION




 §.§ Transit Parameters and Physical Properties


Based on the analysis described above, the physical and orbital parameters for HAT-P-29 system obtained from two global fittings are presented in Table <ref>.

As suggested by previous studies (e.g. ), the discovery light curves obtained from small telescopes like HATNet <cit.>, WASP <cit.>, KELT <cit.>, CSTAR <cit.> are usually with large PSFs, and often contain contaminating light from nearby stars. In addition, flattening routines such as TFA <cit.> or SYSREM <cit.>, which are required to remove red noise from ground-based multi-month datasets <cit.>, often affect the observed transit depth as well. Therefore, although two global fitting results agree with each other very well, we consider the one based on only follow-up photometry as our final result (overplotted in Figures <ref> and <ref>). The following discussion is based on this result.

For comparison, the system parameters, estimated in previous studies <cit.>, are also listed in Table <ref>.

We find almost identical Doppler velocimetric properties to <cit.>, as expected, given that the same RVs were used. The results are also in agreement with those from the discovery work <cit.>, and are consistent with zero eccentricity, as one would expect from a tidally circularized hot Jupiter. 

The known RV trend in the HAT-P-29 system, which was previously reported in <cit.>, can also been seen in our fitting result. It is believed to be caused by an additional companion with a mass between 1-200 and an orbital separation of 2  AU<a<36AU  <cit.>. No further significant RV signal is present in the residuals to our one planet + drift fit, which has a residual RMS scatter of 7.8  m s^-1 and which allows us to place constraints on the mass and the period of an additional companion in the system <cit.>.




Compared to the transit parameters obtained by <cit.>, we find a slightly different solution, with a smaller planet-to-star radius ratio (1.4 σ), a higher orbital inclination (1.2 σ), and a correspondingly smaller impact parameter (1.3 σ). The orbital inclination is observationally strongly tied to the transit's total duration. Our results, therefore, point to a longer transit duration (by 2.8 σ).



Most importantly, we note that our orbital period is 17.63  s longer than the previous measurement, a difference of 4.0 σ. Our predicted mid-time of the next transit event (on UTC 2018 June 1) is 2.5 hrs later than expected according to the orbital ephemeris from <cit.>.

Our new results are based on more extensive photometric data than previous study, so should be more reliable. As shown in <cit.>, limited aggregations of follow-up photometry are sufficient to confirm the planetary nature, but are rather inaccurate for estimating the system parameters.

To demonstrate that the period discrepancies we found do not arise from differences in the fitting process, we also obtained a global fit that is based only on the data from discovery paper <cit.>. As shown in Table <ref>, we successfully recover the result from <cit.>, with the two results displaying excellent agreement.




As expected, given the concordant stellar spectroscopic parameters that were employed <cit.>, the stellar properties (stellar mass M_* and stellar radius R_*) that emerge from our analysis show good agreement with those of <cit.>.

We use our derived photometric, velocimetric, and stellar parameters to infer the physical properties of HAT-P-29b using the method outlined in <cit.>. The physical properties we find for HAT-P-29b agree with those of <cit.> within uncertainties. 




 §.§ Transit Mid-Times






To measure the individual transit mid-times, we perform a separate fit to each of six new light curves collected for this work and to the two follow-up light curves obtained in the discovery paper <cit.>. 
We hold all of the global parameters fixed to the value determined from the joint analysis and fit each transit light curve separately, by allowing only the transit mid-time (T_ C) as well as the light-curve specific baseline flux (F_0) to float.



The resulting transit mid-times (T_ C), measured independently to each new and catalogued light curve, can be found in Table <ref>.







The RMS deviations of these transit mid-times from our updated linear ephemeris is about 275.2  s. This value, however, is significantly affected by the 4.5 σ outlier from the UTC 2013 December 7 transit which was observed duing poor weather conditions, thereby producing a less precise measurement of the transit mid-time. With this weather-affected outlier removed, no statistically significant TTVs are detected at a level above 148.8  s.

Figure <ref> shows the deviations of transit mid-times (blue markers) for HAT-P-29b from the linear orbital ephemeris determined in this work (blue dashed line) and the discovery work (yellow dashed line). 

Given the period discrepancy discussed in 4.1, it is not surprising that the transit ephemeris in the discovery paper (yellow dashed line) disagreed with the transit mid-times we obtained from our new light curves (blue circles). It is interesting, however, that the discovery paper's transit ephemeris even significantly disagreed with the transit mid-times we found from their own follow-up light curves (blue squares). 

This situation arises because the transit mid-times are determined using our best-fitting model, which gives a 30.96  min longer transit duration than <cit.> measured. The transit mid-times for the partial light curves are very sensitive to the transit duration. Transit mid-times (yellow squares) derived using the transit model from <cit.> are therefore in disagreement with the transit mid-times  determined using our best-fitting model (blue squares), but are consistent with their own transit ephemeris (yellow dashed line).

The measured transit mid-times for full transit light curves, however, are insensitive to the model duration. For the two full transit light curves we obtained, the mid-times derived from the best-fitting transit model reported in <cit.> and this work are in good agreement, and are consistent with our updated orbital ephemeris.



 §.§ Limits on an Additional Perturber


The lack of statistically significant TTVs, together with the absence of extra signal in the RV residuals around the one-planet + drift model provide a constraint on the dynamical properties of hypothetical close-in perturbers to HAT-P-29b.

Using dynamical simulations with the MERCURY6 planetary orbital integrator <cit.>, we place an upper limit on the mass of the hypothetical perturber as a function of its orbital period, based on our transit timing analysis of HAT-P-29b. The RMS deviation of its measured transit mid-times from the updated linear orbital ephemeris is approximately 148.8 s.  

For our simulations, the two planets are assumed to be coplanar, and are initially set on circular orbits, a configuration which provides the most conservative estimate of the upper mass limit of the hypothetical perturber, as discussed by <cit.>, <cit.>, and <cit.>.

We explore a perturber's orbit with a semi-major axis between 0.0032 and 0.138 AU (i.e. the period ratio of perturber and known planet from 1:3 to 3:1) in steps of 0.001 AU, which is further reduced to 0.0005  AU in the proximity to resonance since the largest planetary TTVs are likely to arise in or near resonance <cit.>. 
For each orbital separation analyzed, the approximation for the upper mass limit of the hypothetical perturber is obtained iteratively by linear interpolation with an initial mass guess of 1  M_⊕ and with a convergence tolerance for TTVs of 1 s.




lcccccc

0pt
System parameters for HAT-P-29
   Parameter     Units     All follow-up LCs    HATnet+all follow-up LCs     HATNet+2011 follow-up LCs          
Stellar Parameters:                                                                           
                              M_*   Mass ()    1.199_-0.061^+0.063                            1.198_-0.063^+0.065                    1.177_-0.059^+0.064                   1.207 ± 0.046                       1.207 ± 0.046a        

                            R_*   Radius ()    1.237_-0.071^+0.077                            1.229_-0.073^+0.080                    1.176_-0.071^+0.074                   1.224_-0.075^+0.133               ...                                       

                        L_*   Luminosity ()    1.92_-0.25^+0.29                               1.89_-0.25^+0.30                       1.70_-0.23^+0.26                      1.84_-0.26^+0.47                  ...                                       

                            ρ_*   Density (cgs)    0.89_-0.13^+0.15                               0.91_-0.14^+0.16                       1.02_-0.15^+0.18                      ...                                     ...                                       

                 log(g_*)   Surface gravity (cgs)    4.332±0.044                                      4.337_-0.045^+0.044                    4.368±0.045                              4.34 ± 0.06                           4.34 ± 0.06b         

                    Effective temperature (K)    6115±86                                          6112±88                                  6085±87                                  6087 ± 88                             6086 ± 69b     

                                    Metalicity    0.128_-0.080^+0.079                            0.128_-0.080^+0.079                    0.132±0.080                              0.21 ± 0.08                           0.14 ± 0.08b             

Planetary Parameters:                                                                                                                                                                                                                                                                
                                  e   Eccentricity    0.075_-0.027^+0.029                            0.073_-0.028^+0.029                    0.066±0.028                             0.095 ± 0.047                       0.061_-0.036^+0.044                 

       ω_*   Argument of periastron (degrees)    203_-36^+29                                    201_-37^+29                            192_-38^+35                          169 ± 30                            211_-65^+39                         

                                 P   Period (days)    5.723390     ±    0.000013                5.723376 ±        0.000021                     5.723178_-0.00010^+0.000099           5.723186 ± 0.000049                 ...                                       

                          a   Semi-major axis (AU)    0.0665±0.0011                                    0.0665±0.0012                            0.0661_-0.0011^+0.0012                0.0667 ± 0.0008                     ...                                       

                                M_P   Mass ()    0.767_-0.045^+0.047                            0.767_-0.045^+0.046                    0.761_-0.044^+0.045                   0.778_-0.040^+0.076               0.773_-0.051^+0.052                 

                              R_P   Radius ()    1.064_-0.068^+0.075                            1.055_-0.072^+0.079                    1.026_-0.069^+0.073                   1.107_-0.082^+0.136               ...                                       

                          ρ_P   Density (cgs)    0.79_-0.14^+0.17                               0.81_-0.15^+0.18                       0.87_-0.15^+0.19                      0.71 ± 0.18                         ...                                       

                     log(g_P)   Surface gravity    3.224_-0.057^+0.055                            3.232_-0.059^+0.056                    3.252±0.057                             3.20 ± 0.07                        ...                                       

              T_eq   Equilibrium Temperature (K)    1271_-37^+39                                   1266_-39^+41                           1237_-38^+39                          1260_-45^+64                      ...                                       

                          Θ   Safronov Number    0.0798_-0.0063^+0.0066                         0.0806_-0.0066^+0.0068                 0.0831_-0.0066^+0.0072                0.077 ± 0.007                       ...                                       

                     Incident flux ()    0.589_-0.066^+0.076                            0.581_-0.068^+0.078                    0.529_-0.063^+0.070                   0.569_-0.075^+0.136               ...                                       

RV Parameters:                                                                                                                                                                                                                                                                       
                                 ecosω_*        -0.061_-0.024^+0.025                           -0.060_-0.025^+0.026                   -0.055_-0.025^+0.027                  -0.084_-0.046^+0.026              -0.04_-0.031^+0.034                 

                                 esinω_*        -0.024_-0.044^+0.037                           -0.021_-0.042^+0.036                   -0.009_-0.039^+0.035                  0.016 ± 0.058                       -0.02_-0.057^+0.038                 

              T_P   Time of periastron ()    2456464.10_-0.57^+0.48                         2456406.85_-0.58^+0.48                 2455525.29_-0.60^+0.57                ...                                     ...                                       

                       K   RV semi-amplitude (m/s)    77.4_-3.6^+3.8                                 77.5±3.6                                 77.7±3.7                                78.3 ± 5.9                          77.6_-4.6^+4.5                      

                    M_Psin i   Minimum mass ()    0.767_-0.045^+0.047                            0.767_-0.045^+0.046                    0.760_-0.044^+0.045                   ...                                     ...                                       

                          M_P/M_*   Mass ratio    0.000611_-0.000030^+0.000031                   0.000612±0.000030                        0.000617±0.000031                       ...                                     ...                                       

                  γ   Systemic velocity (m/s)    10.9±4.6                                         10.6±4.5                                 11.0_-4.5^+4.4                        ...                                     ...                                       

                 γ̇   RV slope (m/s/day)    0.0491_-0.0086^+0.0085                         0.0485_-0.0084^+0.0085                 0.0499±0.0083                           ...                                     0.0498_-0.01^+0.0092                

Primary Transit Parameters:                                                                                                                                                                                                                                                         
                   T_C   Time of transit ()    2456170.5494 ± 0.0015                            2456445.2740 ± 0.0022        2455523.7982_-0.0027^+0.0030          2455197.57540 ± 0.00181           ...                                       

   R_P/R_*   Radius of planet in stellar radii    0.0885_-0.0011^+0.0012                         0.0883_-0.0012^+0.0013                 0.0897±0.0014                           0.0927 ± 0.0028                     ...                                       

        a/R_*   Semi-major axis in stellar radii    11.56_-0.59^+0.62                              11.64_-0.62^+0.63                      12.09_-0.63^+0.67                     11.70_-0.97^+0.71                 ...                                       

                 u_1   linear limb-darkening coeff    0.260±0.042                                      0.262±0.041                              0.259_-0.047^+0.048                   0.2273                                  ...                                       

              u_2   quadratic limb-darkening coeff    0.293_-0.048^+0.049                            0.298±0.051                              0.296_-0.049^+0.048                   0.3581                                  ...                                       

                         i   Inclination (degrees)    87.99_-0.56^+0.61                              88.06_-0.59^+0.78                      87.22_-0.44^+0.47                     87.1_-0.7^+0.5                    87.1_-0.7^+0.5a   

                              b   Impact Parameter    0.417_-0.12^+0.096                             0.40_-0.15^+0.10                       0.594_-0.088^+0.067                   0.591_-0.094^+0.062               ...                                       

                            δ   Transit depth    0.00782_-0.00020^+0.00022                      0.00779_-0.00022^+0.00023              0.00804±0.00025                         ...                                     ...                                       

                   T_FWHM   FWHM duration (days)    0.1463_-0.0013^+0.0012                         0.1462_-0.0013^+0.0012                 0.1221_-0.0071^+0.0076                ...                                     ...                                       

             τ   Ingress/egress duration (days)    0.0157_-0.0016^+0.0021                         0.0155_-0.0018^+0.0021                 0.0171_-0.0020^+0.0023                0.0177 ± 0.0024                     ...                                       

                    T_14   Total duration (days)    0.1622_-0.0017^+0.0018                         0.1618_-0.0017^+0.0018                 0.1392_-0.0066^+0.0072                0.1407 ± 0.0074                     ...                                       

         P_T   A priori non-grazing transit prob    0.0773_-0.0059^+0.0062                         0.0770_-0.0057^+0.0062                 0.0748_-0.0055^+0.0059                ...                                     ...                                       

                   P_T,G   A priori transit prob    0.0923_-0.0071^+0.0075                         0.0920_-0.0069^+0.0075                 0.0895_-0.0066^+0.0071                ...                                     ...                                       

                               F_0   Baseline flux    0.999946±0.000073                                0.999944±0.000071                        1.000021_-0.000087^+0.000088          ...                                     ...                                       

Secondary Eclipse Parameters:                                                                                                                                                                                                                                                       
                 T_S   Time of eclipse ()    2456465.080_-0.086^+0.091                      2456407.852_-0.090^+0.094              2455526.458_-0.090^+0.097             2455200.132 ± 0.138                 ...                                      

                          b_S   Impact parameter    0.393_-0.11^+0.085                             0.383_-0.14^+0.091                     0.576_-0.085^+0.076                   ...                                     ...                                      

                 T_S,FWHM   FWHM duration (days)    0.1410_-0.0094^+0.0087                         0.1414_-0.0092^+0.0087                 0.1202_-0.0073^+0.0087                ...                                     ...                                      

           τ_S   Ingress/egress duration (days)    0.0148_-0.0016^+0.0019                         0.0146_-0.0016^+0.0020                 0.0164_-0.0021^+0.0027                 0.0183 ± 0.0074                   ...                                      

                  T_S,14   Total duration (days)    0.1560_-0.011^+0.0098                          0.1563_-0.010^+0.0095                  0.1371_-0.0077^+0.0088                 0.1424 ± 0.0107                    ...                                      

         P_S   A priori non-grazing eclipse prob    0.0812_-0.0037^+0.0044                         0.0805_-0.0042^+0.0045                 0.0765_-0.0040^+0.0042                ...                                     ...                                      

                   P_S,G   A priori eclipse prob    0.0969_-0.0046^+0.0055                         0.0961_-0.0052^+0.0056                 0.0916_-0.0049^+0.0051                ...                                     ...                                      

aIn <cit.>, the host stellar mass (M_*) and orbital inclination (i) for the HAT-P-29 system were adopted from <cit.>.
bIn <cit.>, the stellar spectroscopic properties for HAT-P-29 were adopted from <cit.>.






























cccc
0pt
Transit Mid-Times for HAT-P-29b 

Epoch Number     T_ C     σ_T_ C     O-C 

        (BJD_TDB)     (second)      (second) 


-106       2455563.87156        55.89        125.23 

 -102       2455586.76257        53.09       -95.59 

    77       2456611.2506          120.41          9.52   

    81       2456634.1356          253.52         -728.18   

    85       2456657.0363        94.53       -109.24   

    92       2456697.1006          143.24           -60.05    

   142      2456983.2670          368.96         -327.55     

   150      2457029.05882          58.88          76.44 



The upper limits on the mass of the hypothetical perturber in the HAT-P-29 system that are determined by these simulations are illustrated in Figure <ref>.
While the Doppler residuals with an RMS of 7.8 m s^-1 provide stronger constraints on the “maximum minimum mass” <cit.> of the hypothetical perturber on most configurations (dashed line in the figure), the mass constraints from the TTVs technique (solid black line) are more restrictive at the low-order mean-motion resonances. We can rule out the presence of a perturber with mass greater than 0.6, 0.7, 0.5, and 0.4  M_⊕ near the 1:2, 2:3, 3:2, and 2:1 resonances, respectively.





According to the Mean Exponential Growth of Nearby Orbits  (MEGNO) Index <cit.>, we also show the chaotic/quasi-periodic dynamics for the three-body system in the same figure. The resulting MEGNO map and, in particular the dynamical (chaotic) properties in the vicinity of the transiting planet (large mutual perturbations), is qualitatively consistent with the orbital stability limits derived using the method outlined in <cit.>.



§ SUMMARY AND CONCLUSIONS


Planet “hunting” is gradually losing its cachet, and is being supplanted by renewed efforts to characterize the known planetary inventory. We, therefore, have initiated a ground-based photometric follow-up project, TEMP, to aid this broader effort, hopefully helping to foster a new understanding of the formation, and evolution of exoplanetary systems.

In our inaugural efforts, we have presented photometry of six transits of HAT-P-29b, obtained between 2013 October and 2015 January with two different telescopes, 
which quadruples the number of published transit light curves available for this planetary system to date. 
The new light curves have photometric scatter ranging from 1.9 to 3.7 mmag and a typical exposure time of 35-100 s.
 
We analyzed our new photometric data, along with two follow-up light curves presented in the discovery paper <cit.>, the RV measurements <cit.>, and improved spectroscopic properties of the host star <cit.> to confirm and refine the orbital and physical properties of the HAT-P-29 system. Our improved orbital period is 17.63 ± 4.38s longer than previous measurements <cit.>, a difference of 4.0 σ, facilitating future characterization of the system during the transit (e.g. the wavelength-dependent transmission spectrum and/or the Rossiter-McLaughlin measurements).

The lack of TTVs with a standard deviation larger than 148.8 s placed an upper limit on the mass of a nearby hypothetical perturber as a function of its orbital separation. These mass constraints are particularly restrictive at the low-order mean-motion resonances. Near the 1:2, 2:3, 3:2, and 2:1 resonances with HAT-P-29b, perturbers with masses greater than 0.6, 0.7, 0.5, and 0.4  M_⊕ can be excluded, respectively. Away from mean-motion resonance, the RV residuals, with an RMS of 7.8 m s^-1, indicate HAT-P-29 system could readily be harboring additional short-period Neptune-mass companions. Thus, further observations of HAT-P-29, both through photometry and Doppler velocimetry, would be useful in helping to assess the presence of additional nearby planets in the system, especially in dynamically stable non-resonant orbits. The presence or absence of such planets provides direct insight into the formation and evolution processes of hot Jupiters.


For the coming flood of planetary candidates from K2 and TESS that require photometric follow-up observations, 
we plan to involve more telescopes in our project to obtain high-precision photometric light curves with the aim to improve physical and orbital properties of transiting exoplanetary systems with poor data coverage. 
In particular we plan to make dramatic progress towards sub-mmag photometric precision by the use of the autoguider and the beam-shaping diffusers <cit.>.




Acknowledgments  


We thank the anonymous referee for the insightful suggestions that greatly improved this manuscript.

S.W. thanks the Heising-Simons Fundation for their generous support.

This work is supported by the National Basic Research Program of China (Nos. 2014CB845704, and 2013CB834902);
the National Natural Science Foundation of China (Grant No. 11503009, 11333002, 11673011, 11373033, 11433005, 11673027, 11633009);
the CAS “Light of West China” program (2015-XBQN-A-02);
JSPS KAKENHI Grant Number JP18H01265; 
the National Defense Science and Engineering Bureau civil spaceflight advanced research project (D030201);
Minor Planet Foundation of Purple Mountain observatory.

T. C. H. acknowledges KASI research grant 2016-1-832-01.
Numerical computations were partly carried out using the SFI/HEA Irish Center for High-End Computing (ICHEC) and the 3rd generation Polaris High-Performance Computing cluster at KASI/South Korea.

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