4XMM-DR13

4XMM-DR13 is the fourth generation catalogue of serendipitous X-ray sources from the European Space Agency's (ESA) XMM-Newton observatory, and has been created by the XMM-Newton Survey Science Centre (SSC) on behalf of ESA. It is an incremental version of the the 4XMM catalogue and contains 531 more observations and 44678 more detections than the preceding 4XMM-DR12 catalogue, which was made public in July 2022. In addition, we provide spectra and lightcurves for more than 16762 more detections than in 4XMM-DR12. The catalogue contains source detections drawn from a total of 13243 XMM-Newton EPIC observations made between 2000 February 1 and 2022 December 31; all datasets included were publicly available by 2022 December 31 but not all public observations are included in this catalogue. For net exposure time ≥ 1ksec, the net area of the catalogue fields taking account of the substantial overlaps between observations is ~ 1328 deg2. 4XMM-DR13 contains 983948 X-ray detections above the processing likelihood threshold of 6. These X-ray detections relate to 656997 unique X-ray sources. A significant fraction of sources (129133, 20%) have more than one detection in the catalogue (up to 90 repeat observations in the most extreme case). The catalogue distinguishes between extended emission and point-like detections. Parameters of detections of extended sources are only reliable up to the maximum extent measure of 80 arcseconds. There are 91763 detections of extended emission, of which 20971 are 'clean' (in the sense that they were not flagged). Due to intrinsic features of the instrumentation as well as some shortcomings of the source detection process, some detections are considered to be spurious or their parameters are considered to be unreliable. It is recommended to use a detection flag and an observation flag as filters to obtain what can be considered a 'clean' sample. There are 854095 out of 983948 detections that are considered to be clean (i.e., summary flag < 3). For 353538 detections, EPIC time series and 353821 detections, EPIC spectra were automatically extracted during processing, and a χ2-variability test was applied to the time series. 8029 detections in the catalogue are considered variable, within the timespan of the specific observation, at a probability of 10-5 or less based on the null-hypothesis that the source is constant. Of these, 6039 have a summary flag < 3. The median flux (in the total photon-energy band 0.2 - 12 keV) of the catalogue detections is ~ 2.2 × 10-14 erg/cm2/s; in the soft energy band (0.2 - 2 keV) the median flux is ~ 5.2 × 10-15, and in the hard band (2 - 12 keV) it is ~ 1.2 × 10-14. About 23% have fluxes below 1 × 10-14 erg/cm2/s. The flux values from the three EPIC cameras are, overall, in agreement to ~ 10% for most energy bands. The median positional accuracy of the catalogue point source detections is generally < 1.57 arcseconds (with a standard deviation of 1.43). With 4XMM-DR13, we also release 4XMM-DR13s, a new version of the stacked catalogue built from 9796 4XMM-DR13 overlapping observations. 4XMM-DR13s contains 1688 stacks (or groups). Most of the stacks are composed of 2 observations and the largest has 372. The catalogue contains 401596 sources, of which 310478 have several contributing observations. Stacking observations allows yet fainter sources to be detected in sky regions observed more than once, increasing the number of detections and uncovering long-term variability on repeatedly observed objects. 4XMM-DR13s reaches a median depth of ~2.5E-15 and ~6.8E-15 erg/cm2/s in the soft (0.2-2 keV) and hard (2-12 keV) X-ray band, respectively.4XMM-DR13是欧洲空间局（European Space Agency, ESA）XMM-牛顿天文台（XMM-Newton observatory）产出的第四代偶然发现X射线源星表，由XMM-牛顿巡天科学中心（XMM-Newton Survey Science Centre, SSC）受ESA委托编制。其为4XMM星表的增量更新版本，相较于2022年7月发布的前代4XMM-DR12星表，新增了531次观测数据与44678个X射线源探测结果；此外，本星表较4XMM-DR12额外提供了超过16762个探测源的能谱与光变曲线。 本星表的探测源源自2000年2月1日至2022年12月31日期间获取的共计13243次XMM-牛顿EPIC（XMM-Newton EPIC）观测数据；所有纳入本星表的数据集均于2022年12月31日前公开，但并非所有公开观测数据均被收录其中。当有效曝光时间≥1千秒时，考虑观测间大量重叠区域后，本星表覆盖的有效天区面积约为1328平方度。 4XMM-DR13共包含983948个高于处理似然阈值6的X射线探测结果，对应656997个独一无二的X射线源。其中占比20%的129133个源在星表中拥有不止一次探测结果，极端情况下单个源的重复观测次数可达90次。 本星表对延展辐射源与类点源探测结果进行了区分。延展源的探测参数仅在角尺度测量值不超过80角秒时可靠。本星表中共包含91763个延展辐射探测结果，其中20971个为"干净"探测（即未被标记的探测结果）。 受仪器固有特性与源探测流程的部分缺陷影响，部分探测结果被判定为伪影或其参数不可靠。建议通过探测标记与观测标记进行筛选，以获取"干净"的有效样本。在全部983948个探测结果中，共有854095个被认定为干净探测（即总标记值<3）。 在数据处理过程中，自动为353538个探测结果提取了EPIC时间序列数据，并为353821个探测结果提取了EPIC能谱；随后对时间序列实施了χ²变异性检验。在单次观测的时间跨度内，基于"源为恒定"的原假设，本星表中有8029个探测结果被判定为变源，其变异性置信概率≤10^-5。其中6039个的总标记值<3。 本星表所有探测结果的总光子能段（0.2~12 keV）中值流量约为2.2×10^-14 erg/cm²/s；软能段（0.2~2 keV）的中值流量约为5.2×10^-15 erg/cm²/s，硬能段（2~12 keV）则约为1.2×10^-14 erg/cm²/s。约23%的探测结果流量低于1×10^-14 erg/cm²/s。整体而言，三台EPIC相机获取的流量值在多数能段下的一致性约为10%。本星表类点源探测结果的位置中值精度普遍低于1.57角秒（标准差为1.43角秒）。 本次发布的4XMM-DR13同时附带4XMM-DR13s——一款基于9796次4XMM-DR13重叠观测构建的堆叠星表新版本。4XMM-DR13s共包含1688个堆叠组（或称群组），其中多数堆叠组由2次观测构成，最大堆叠组包含372次观测。该星表涵盖401596个源，其中310478个源拥有多组贡献观测数据。堆叠观测技术可在多次观测过的天区中探测到更暗弱的源，从而提升探测总数并揭示重复观测天体的长期变异性。4XMM-DR13s在软X射线能段（0.2~2 keV）与硬X射线能段（2~12 keV）的中值探测深度分别约为2.5×10^-15 erg/cm²/s与6.8×10^-15 erg/cm²/s。