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Description
The stacked catalog 4XMM-DR13s (<a href="/W3Browse/xmm-newton/xmmstack.html">XMMSTACK</a>) has been compiled from 1,688 groups, comprising 9,796 overlapping good-quality XMM-Newton observations. They were selected from the public observations taken between 2000 February 1 and 2022 November 29 which overlap by at least one arcminute in radius. It contains 401,596 unique sources, 310,478 of them multiply observed, with positions and source parameters like fluxes in the XMM-Newton standard energy bands, hardness ratios, quality estimate, and information on inter-observation variability. The parameters are directly derived from the simultaneous fit, and, wherever applicable, additionally calculated for each contributing observation. Exposures that do not qualify for source detection, for example because of a high background level, are used for subsequent PSF photometry: source fluxes and flux-related parameters are derived for them at the source position and extent found during source detection. 4XMM-DR13s lists 1,683,264 individual flux measurements of the 401,596 unique sources. Stacked source detection aims at exploring the multiply observed sky regions and exploit their survey potential, in particular to study the long-term behavior of X-ray emitting sources. It thus makes use of the long(er) effective exposure time per sky area and offers the opportunity to investigate flux variability directly through the source detection process. The main catalog properties are summarized in the table below, the data processing and the stacked source detection are described in the processing summary. To ensure detection quality, background levels are assessed, and event-based astrometric corrections are applied before running source detection. After source detections, problematic detections and detection parameters are flagged by an automated algorithm. All detections are screened visually, and obviously spurious sources are flagged manually. This table contains the source parameters from the individual observations in the stacked catalog, <a href="/W3Browse/xmm-newton/xmmstack.html">4XMM-DR13s</a>. The parameters are derived from the simultaneous source-detection fit to all stacked observations at the common source position for each observation that covers a source, amounting to 1,683,264 measurements. The mean source parameters from stacked source detection are provided in the associated main table <a href="/W3Browse/xmm-newton/xmmstack.html">4XMM-DR13s</a>, referred to as XMMSTACK. The authors referred to the EPIC instruments with the following designations: PN, M1 (MOS1), and M2 (MOS2). The energy bands used in the 4XMM processing were the same as for the 3XMM catalog. The following are the basic energy bands: <pre> 1: 0.2-0.5 keV 2: 0.5-1.0 keV 3: 1.0-2.0 keV 4: 2.0-4.5 keV 5: 4.5-12.0 keV </pre> All-EPIC values cover the energy range 0.2-12.0 keV. The full catalog documentation can be found at <a href="https://xmmssc.aip.de/">https://xmmssc.aip.de/</a>. The following table gives an overview of the statistics of this catalog in comparison with the previous stacked catalogs, 4XMM-DR13s through 3XMM-DR7s: <pre> 4XMM-DR13s 4XMM-DR12s 4XMM-DR11s 4XMM-DR10s 4XMM-DR9s 3XMM-DR7s Number of stacks 1,688 1,620 1,475 1,396 1,329 434 Number of observations 9,796 9,355 8,292 7,803 6,604 789 Time span first to last observation Feb 01, 2000 Feb 01, 2000 Feb 03, 2000 Feb 03, 2000 Feb 03, 2000 Feb 20, 2000 -- Nov 29, 2022 -- Dec 04, 2021 -- Dec 17, 2020 -- Dec 14, 2019 -- Nov 13, 2018 -- Apr 02, 2016 Approximate sky coverage (sq. deg.) 650 625 560 540 485 150 Approximate multiply observed sky area(sq. deg) 420 400 350 335 300 100 Total number of sources 401,596 386,043 358,809 335,812 288,191 71,951 Sources with several contributing observations 310,478 298,626 275,440 256,213 218,283 57,665 Multiply observed sources with flag 0 or 1 262,842 252,445 233,542 216,999 191,497 55,450 Multiply observed with a total detection 251,555 241,880 224,178 208,921 181,132 49,935 likelihood of at least six Multiply observed with a total detection 213,812 205,394 189,556 176,680 153,487 42,077 likelihood of at least ten Total measurements 1,683,264 1,592,263 1,421,966 1,322,299 1,033,264 216,393 Maximum exposures per source 170 155 140 140 103 69 Maximum observations per source 77 70 65 65 40 23 Maximum on-time per source 2.8 Ms 2.8 Ms 2.8 Ms 2.8 Ms 1.9 Ms 1.3 Ms </pre> This database table was last updated by the HEASARC in December 2023 in order to remove 49 duplicate entries. It contains the 4XMM-DR13s source catalog, released by ESA on 2023-06-12 and obtained from the XMM-Newton Survey Science Center Consortium at <a href="https://xmmssc.aip.de/cms/catalogues/4xmm-dr13s/">https://xmmssc.aip.de/cms/catalogues/4xmm-dr13s/</a>. It is <a href="https://xmmssc.aip.de/data/xmmstack_v3.1_4xmmdr13s.fits.gz">also available as a gzipped FITS file</a>. This is a service provided by NASA HEASARC .
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