Qatar-1b 是一個被觀測到有掩星現象的系外行星，被曾經被宣稱這個系統可能有 transit timing variation (TTV)的訊號，或許是由於有其他的星體存在，在這個系外行星系統並對 Qatar-1b 的運行軌道造成影響而產生。所以我們收集了來自 Palomar 天文台及克里米亞天文台的 10 條掩星光變曲線，再加上從以前文獻上得到了，總共 40 條光變曲線作分析。我們使用 Transit Analysis Package (TAP) 來得到這個系統的軌道及恆星參數以及各自的誤差。接著把每次的掩星事件中心時間去擬合線性的函式，得到了 reduced χ 2 為 0.3938，並利用其結果和觀測值做比較，把這個差值拿去做週期性震盪的擬合，我們使用了三個可能的頻率，0.03881、0.02998 以及 0.00554，並分別得到了 reduced χ 2 為 4.02、3.643 以及 4.047。而我們考慮了這個擬合的錯誤機率(FAP)，顯示沒有任何震幅大於 25 秒的週期性的 TTV 訊號存在其中。

Qatar-1b is a transiting exoplanet which was claimed with possible transit timing variation (TTV) in this system. We have obtained ten light curves from our observations using the Palomar Observatory and the Crimean Astrophysical Observatory, combined with the public data in literatures, there are 40 light curves in total. Transit Analysis Package (TAP) is a package we use to get refined system parameters and uncertainties. The null TTV produces a fit with χ2red = 3.938. The residuals of linear fitting to mid- transit time of each transit infer there might be possible TTV. We have used three possible frequencies, 0.03881, 0.02998 and 0.00554, to fit sinusoidal function and the result of χ2red are 4.02, 3.643 and 4.047. Then we also check the false alarm probability of the frequencies, and it shows that there is no evidencd for periodic TTVs with a amplitude more than abou 25 seconds.

1 Introduction 6
2 Observation and Data Reduction 8
2.1 TheObservatoryandTelescopes ................................ 8
2.1.1 PalomarObservatory .................................. 8
2.1.2 CrimeanAstrophysicalObservatory .......................... 9
2.2 ObservationandDataReduction ................................ 10
2.2.1 DataCalibration..................................... 10
2.2.2 SelectionofComparisonStar .............................. 11
2.2.3 TheNormalizationofLightCurves........................... 12
2.3 LightCurvesfromtheLiterature ................................ 13
3 The Analysis of Light Curves 16
3.1 InitialValuesofthePlanetarySystemParameters ...................... 16
3.2 TheResultsofLightCurveModeling.............................. 18
4 Timing Analysis 30
4.1 NewEphemeris.......................................... 30
4.2 FrequencyAnalysis........................................ 33
5 The Summary
A The Figures of Normalized Results

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