Radial velocities and activity time-series measurements for the star "HD42936" ("DMPP-3")

These data are the underlying measurements behind a search for exoplanets around the star with the name HD42936 (with the identifier DMPP-3 given by the Dispersed Matter Planet Project, DMPP, working at the Open University). The files consist of: radial velocities, the measurements of motion towards and away from earth-based observers we can use to determine if planets are pulling the star around as they orbit, taken with the HARPS spectrograph on the 3.6m telescope in La Silla; and measurements of the star's activity level (monitoring presence of features like starspots and stellar flares) at each observation time, extracted from different aspects of the spectra recorded with the spectrograph.
For information on the DMPP, see Haswell, C. A.,  et al., 2020, “Dispersed Matter Planet Project discoveries of ablating planets orbiting nearby bright stars”, Nature Astronomy, 4, 408.

HD42936_TERRA_RV.txt : contains the HARPS-TERRA reduced radial velocities for this system. The columns are:
Time (BJD-2450000); Radial Velocity (m/s); Error on RV (m/s); and Observational Dataset (dimensionless numbering). BJD is the Barycentric Julian Date, and a measure of time, in days, from a reference epoch.
TERRA uses a template matching process to extract radial velocities in a more accurate manner. For more information see Anglada-Escudé G., Butler R. P., 2012, ApJS, 200, 15

HD42936_DRS_BIS.txt, HD42936_DRS_FWHM.txt, HD42936_DRS_CCF_contrast.txt: these files contain the ancillary measurements from HARPS spectra, originating from the HARPS data reduction software (DRS). The full width half max (FWHM), bisector inverse slope (BIS) and contrast are measured from the cross-correlation function approach used in extracting radial velocities. They can all be used to investigate changes in the activity level of the star. These files have columns of: 
FWHM: Time (BJD); Value (km/s); error (km/s)
BIS: Time (BJD-2400000); Value (m/s); error (m/s)
Contrast: Time (BJD); Value (%, dimensionless); error (%, dimensionless)

HD42936_corrected_FWHM.txt: FWHM values after correction, where 4 outlying points have been removed in total, as well as removing a polynomial trend evident in HARPS pre fibre upgrade points, and a fibre upgrade related offset. For information on this trend, see Costes J. C., et al., 2021, MNRAS, 505, 830.
The columns of this file are: Time (BJD); Median Subtracted FWHM value (km/s); FWHM error (km/s)

HD42936_CaHK_JB.txt, HD42936_Halpha_JB.txt, HD42936_NaD1_JB.txt, HD42936_NaD2_JB.txt, HD42936_NaD1D2_JB.txt: Activity time series values, reduced from publicly available HARPS spectra (ESO archive). We have extracted line strengths for Calcium II H and K, Hydrogen alpha, Sodium D lines 1, 2, and 1&2 combined. These have been extracted using optimised, uniform (rectangular) line summing, with differing line core respective passband half widths. 0.3 [Angstroms] for Ca H, Na D1 & D2. 0.25 [Angstroms] for Hydrogen alpha. 0.2 [Angstroms] for Ca K. For further information on the reduction process used, see Barnes J. R., Haswell C. A., Staab D., Anglada-Escudé G., 2016, MNRAS,
462, 1012.
The columns of these files are in the format of: Time (BJD-2400000); line strength value (dimensionless); Error on value (dimensionless).

本数据集包含了围绕名为HD42936（由分散物质行星项目，DMPP，在开放大学工作期间赋予标识符DMPP-3）的恒星周围的系外行星搜寻的底层测量数据。数据文件包括：径向速度，即地球观测者相对于地球运动向和远离的测量值，可用于判断行星在轨道运行时是否牵引恒星绕其旋转，这些测量值由位于拉西拉3.6米望远镜上的HARPS光谱仪获得；以及在每个观测时间点对恒星活动水平的测量（监测诸如星斑和恒星耀斑等特征的存在），这些测量值从光谱仪记录的不同光谱方面提取。有关DMPP的信息，请参阅Haswell, C. A. 等，2020年，《自然天文学》第4卷，第408页。

HD42936_TERRA_RV.txt：包含该系统的HARPS-TERRA径向速度数据。列包括：时间（BJD-2450000）；径向速度（m/s）；径向速度误差（m/s）；观测数据集（无量纲编号）。BJD是动心日历，是一种从参考历元起算的天数，单位为天。TERRA采用模板匹配过程以更精确的方式提取径向速度。更多信息请参阅Anglada-Escudé G.，Butler R. P.，2012年，《天文期刊增刊》第200卷，第15页。

HD42936_DRS_BIS.txt、HD42936_DRS_FWHM.txt、HD42936_DRS_CCF_contrast.txt：这些文件包含来自HARPS光谱的辅助测量数据，源自HARPS数据降低软件（DRS）。通过交叉相关函数方法提取径向速度时，测量了全宽半高（FWHM）、分束器逆斜率（BIS）和对比度。所有这些都可以用于研究恒星活动水平的变化。这些文件具有以下列：FWHM：时间（BJD）；值（km/s）；误差（km/s）；BIS：时间（BJD-2400000）；值（m/s）；误差（m/s）；对比度：时间（BJD）；值（%，无量纲）；误差（%，无量纲）。

HD42936_corrected_FWHM.txt：经过校正的FWHM值，其中总共移除了4个异常点，以及移除了在HARPS光纤升级前点中明显存在的多项式趋势和与光纤升级相关的偏移。关于此趋势的信息，请参阅Costes J. C. 等，2021年，《天文学报》第505卷，第830页。该文件的列包括：时间（BJD）；中值减去FWHM值（km/s）；FWHM误差（km/s）。

HD42936_CaHK_JB.txt、HD42936_Halpha_JB.txt、HD42936_NaD1_JB.txt、HD42936_NaD2_JB.txt、HD42936_NaD1D2_JB.txt：活动时间序列值，由公开可用的HARPS光谱（ESO档案）减少而成。我们提取了钙II H和K、氢α、钠D线1、2以及1和2结合的线强度。这些提取使用了优化、均匀（矩形）线求和，具有不同的线核心相应的通带半宽度。Ca H、Na D1和D2为0.3 [埃]; 氢α为0.25 [埃]; Ca K为0.2 [埃]。关于所使用减少过程的更多信息，请参阅Barnes J. R.，Haswell C. A.，Staab D.，Anglada-Escudé G.，2016年，《天文学报》第462卷，第1012页。这些文件的列格式为：时间（BJD-2400000）；线强度值（无量纲）；值误差（无量纲）。