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NGC 6231 Chandra X-Ray Point Source Catalog 2
NGC 6231 is a young cluster (age ~2-7 Myr) dominating the Sco OB1 association (distance ~1.59 kpc) with ~100 O and B stars and a large pre-main-sequence stellar population. The authors combine a reanalysis of archival Chandra X-ray data with multi-epoch near-infrared (NIR) photometry from the VISTA Variables in the Via Lactea (VVV) survey and published optical catalogs to obtain a catalog of 2148 probable cluster members. This catalog is 70% larger than previous censuses of probable cluster members in NGC 6231. It includes many low-mass stars detected in the NIR but not in the optical and some B stars without previously noted X-ray counterparts. In addition, the authors identify 295 NIR variables, about half of which are expected to be pre-main-sequence stars. With the more complete sample, they estimate a total population in the Chandra field of 5700-7500 cluster members down to 0.08 M<sub>sun</sub> (assuming a universal initial mass function) with a completeness limit at 0.5 M<sub>sun</sub>. A decrease in stellar X-ray luminosities is noted relative to other younger clusters. However, within the cluster, there is little variation in the distribution of X-ray luminosities for ages less than 5 Myr. The X-ray spectral hardness for B stars may be useful for distinguishing between early-B stars with X-rays generated in stellar winds and B-star systems with X-rays from a pre-main-sequence companion (>35% of B stars). A small fraction of catalog members have unusually high X-ray median energies or reddened NIR colors, which might be explained by absorption from thick or edge-on disks or being background field stars. This work makes use of some basic cluster properties available from the literature. Summaries of older studies are provided by Sana et al. (2006, J/A+A/454/1047), available in <a href="/W3Browse/xmm-newton/ngc6231xmm.html">NGC6231XMM</a>, and Reipurth (2008hsf2.book.....R). Expanded catalogs of cluster members have been provided by Sung et al. (2013, J/AJ/145/37) and Damiani et al. 2016, J/A+A/596/A82 (DMS2016), available at <a href="/W3Browse/chandra/ngc6231cxo.html">NGC6231CXO</a>. Chandra X-ray observations were made using the imaging array on the Advanced CCD Imaging Spectrometer (ACIS-I; Garmire et al. 2003SPIE.4851...28G). This instrument is an array of four CCD detectors that subtends 17'x17'. The target was observed in 2005 July (Sequence 200307; PI: S. Murray) in two observations (ObsID 5372 and 6291), and the data were retrieved from the Chandra Data Archive. The NIR ZYJHK<sub>s</sub> data were obtained from the VVV survey (Minniti et al. 2010NewA...15..433M; Saito et al. 2012, Cat. II/337). VVV is a multi-epoch NIR survey that covers both the Galactic bulge and an adjacent Galactic disk region and was carried out using the 4.1 m VISTA telescope on Cerro Paranal. The VVV data were taken with the VISTA Infrared CAMera (VIRCAM; Dalton et al. 2006SPIE.6269E..0XD), a 4x4 array of Raytheon VIRGO 2048x2048 20 micron pixel detectors with a pixel scale of 0.34". In addition to the VVV photometry, public optical or infrared catalogs are available from surveys and publications. We have included VPHAS+ photometry (Drew et al. 2014, J/MNRAS/440/2036), UBVRI (Johnson-Cousins system) and H-alpha photometry from Sung et al. (2013, J/AJ/145/37), and Spitzer/IRAC photometry from the GLIMPSE survey (Benjamin et al. 2003, Cat. II/293). This table was created by the HEASARC in October 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/154/87">CDS Catalog J/AJ/154/87</a> file table1.dat, table3.dat, and table5.dat. This is a service provided by NASA HEASARC .
NGC 1399 Chandra X-Ray Source Catalog
This table contains results from a wide-field study of the globular cluster (GC)/low-mass X-ray binary (LMXB) connection in the giant elliptical NGC 1399. The large field of view of the Advanced Camera for Surveys/WFC, combined with the high resolution of the Hubble Space Telescope and Chandra, allow the authors to constrain the LMXB formation scenarios in elliptical galaxies. They confirm that NGC 1399 has the highest LMXB fraction in GCs of all nearby elliptical galaxies studied so far, even though the exact value depends on galactocentric distance due to the interplay of a differential GC versus galaxy light distribution and the GC color dependence. In fact, LMXBs are preferentially hosted by bright, red GCs out to > 5 R<sub>eff</sub> of the galaxy light. The finding that GCs hosting LMXBs follow the radial distribution of their parent GC population argues against the hypothesis that the external dynamical influence of the galaxy affects the LMXB formation in GCs. On the other hand, field-LMXBs closely match the host galaxy light, thus indicating that they are originally formed in situ and not inside GCs. The authors measure GC structural parameters, finding that the LMXB formation likelihood is influenced independently by mass, metallicity, and GC structural parameters. In particular, the GC central density plays a major role in predicting which GCs host accreting binaries. Finally, this analysis shows that LMXBs in GCs are marginally brighter than those in the field, and in particular the only color-confirmed GC with L<sub>X</sub> > 10<sup>39</sup> erg/s shows no variability, which may indicate a superposition of multiple LMXBs in these systems. The optical data were taken with the ACS on board the HST (GO-10129), in the F606W filter. A detailed description of the HST data and source catalogs are given in Puzia T.H. et al. 2011, in preparation. The X-ray data were retrieved from the Chandra public archive (CXC). The authors selected observations 319 (ACIS-S; 2000 Jan 18) and 1472 (ACIS-I; 2003 May 26). This table contains the list of 230 X-ray sources detected in the overlap region common to Chandra ACIS-I, Chandra ACIS-S and HST ACS observation (see Fig 1 of the reference paper). Details of the X-ray source detection methodology are given in Section 2.2 of the reference paper. This table was created by the HEASARC in January 2013 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/736/90">CDS Catalog J/ApJ/736/90</a> file table3.dat. This is a service provided by NASA HEASARC .
NGC 2237 Chandra X-Ray Point Source Catalog
The authors have obtained high spatial resolution Chandra X-ray images of the NGC 2237 young stellar cluster on the periphery of the Rosette Nebula. They detect 168 X-ray sources, 80% of which have stellar counterparts in USNO, Two Micron All Sky Survey, and deep FLAMINGOS images. These constitute the first census of the cluster members with 0.2 <~ M <~ 2 M<sub>sun</sub>. Star locations in near-infrared color-magnitude diagrams indicate a cluster age of around 2 Myr with a visual extinction of 1 <~ AV <~ 3 at 1.4 kpc, the distance of the Rosette Nebula's main cluster NGC 2244. The authors derive the K-band luminosity function and the X-ray luminosity function of the cluster, which indicate a population of ~ 400-600 stars. The X-ray-selected sample shows a K-excess disk frequency of 13%. The young Class II counterparts are aligned in an arc ~3 pc long suggestive of a triggered formation process induced by the O stars in NGC 2244. The diskless Class III sources are more dispersed. Several X-ray emitting stars are located inside the molecular cloud and around gaseous pillars projecting from the cloud. These stars, together with a previously unreported optical outflow originating inside the cloud, indicate that star formation is continuing at a low level and the cluster is still growing. This X-ray view of young stars on the western side of the Rosette Nebula complements the authors' earlier studies of the central cluster NGC 2244 and the embedded clusters on the eastern side of the Nebula. The large-scale distribution of the clusters and molecular material is consistent with a scenario in which the rich central NGC 2244 cluster formed first, and its expanding H II region triggered the formation of the now-unobscured satellite clusters Rosette Molecular Cloud (RMC) XA and NGC 2237. A large swept-up shell of material around the H II region is now in a second phase of collect-and-collapse fragmentation, leading to the recent formation of subclusters. Other clusters deeper in the molecular cloud appear unaffected by the Rosette Nebula expansion. Some sources which have information from published catalogs are listed by their source_number value below, where for convenience, [OI81] = Ogura & Ishida (1981, PASJ, 33, 149), [MJD95] = Massey, Johnson, & Degioia-Eastwood (1995, ApJ, 454, 151) and [BC02] = Berghofer & Christian (2002, A&A, 384, 890): <pre> 53 = [OI81] 14 = [MJD95] 104; spectral type B1V; pmRA=11.0 mas/yr, pmDE=-2.8 mas/yr; 54 = [OI81] 10 = [MJD95] 108; spectral type B2V; pmRA=-2.3 mas/yr, pmDE=-11.9 mas/yr; 61 = V539 Mon [OI81] 13 = [MJD95] 110; MSX6C G206.1821-02.3456; pmRA=2.8 mas/yr, pmDE=0.4 mas/yr; 71 = [OI81] 12 = [MJD95] 102; pmRA=6.8 mas/yr, pmDE=0.6 mas/yr; 128 = [OI81] 35 = [MJD95] 471; spectral type A2:; pmRA=-0.8 mas/yr, pmDE=3.6 mas/yr; 138 = [OI81] 36 = [MJD95] 497; spectral type B5; pmRA=6.5 mas/yr, pmDE=2.1 mas/yr; 141 = [MJD95] 498; pmRA=-3.0 mas/yr, pmDE=1.9 mas/yr; 149 = [BC02] 11; known X-ray source; log(Lx(ROSAT/PSPC))=31.01 erg/s; pmRA=0.6 mas/yr, pmDE=-12.6 mas/yr; 161 = [MJD95] 653; pmRA=-1.0 mas/yr, pmDE=-5.4 mas/yr </pre> This table was created by the HEASARC in July 2010 based on electronic versions of Tables 1, 2, 3 and 4 of the reference paper which were obtained from the electronic ApJ web site. To distinguish between the 130 X-ray sources in the primary sample (Table 1 of the reference paper) and the 38 X-ray sources in the tentative sample (Table 2 of the reference paper), the HEASARC has created a parameter called source_sample which is set to 'P' for the primary sources and to 'T' for the tentative sources. This is a service provided by NASA HEASARC .
NGC 2244/Rosette Nebula Chandra X-Ray Point Source Catalog
This table contains the point source catalog based on the first high spatial resolution X-ray study of NGC 2244, the 2 Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected within 20 arcminutes of the cluster central position (J2000.0 RA and Dec of 6 31 59.9, +4 55 36); 77% of these X-ray sources have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members. The X-ray-selected population is estimated to be nearly complete between 0.5 and 3 M<sub>solar</sub>. A number of further results emerge from the analysis: (1) The X-ray luminosity function (XLF) and the associated K-band LF indicate a normal Salpeter IMF for NGC 2244. This is inconsistent with the top-heavy IMF reported from earlier optical studies that lacked a good census of < 4 M<sub>solar</sub> stars. By comparing the NGC 2244 and Orion Nebula Cluster XLFs, the authors estimate a total population of ~2000 stars in NGC 2244. (2) The spatial distribution of X-ray stars is strongly concentrated around the central O5 star, HD 46150. The other early O star, HD 46223, has few companions. The cluster's stellar radial density profile shows two distinctive structures: a power-law cusp around HD 46150 that extends to ~0.7 pc, surrounded by an isothermal sphere extending out to 4 pc with core radius 1.2 pc. This double structure, combined with the absence of mass segregation, indicates that this 2 Myr old cluster is not in dynamical equilibrium. (3) The fraction of X-ray-selected cluster members with K-band excesses caused by inner protoplanetary disks is 6%, slightly lower than the 10% disk fraction estimated from the FLAMINGOS study based on the NIR-selected sample. (4) X-ray luminosities for 24 stars earlier than B4 confirm the long-standing log (L<sub>X</sub>/L<sub>bol</sub>) ~ -7 relation. The Rosette OB X-ray spectra are soft and consistent with the standard model of small-scale shocks in the inner wind of a single massive star. This table was created by the HEASARC in July 2008 based on electronic versions of Tables 2, 3, 4, 5 and 6 of the reference paper which were obtained from the electronic ApJ web site. This is a service provided by NASA HEASARC .
NGC 4278 Chandra X-Ray Point Source Catalog
This table lists some of the properties of the discrete X-ray sources detected in the authors' monitoring program of the globular cluster (GC)-rich elliptical galaxy, NGC 4278, observed with Chandra ACIS-S in six separate pointings, resulting in a co-added exposure of 458 ks. From this deep observation, 236 sources have been detected within the region overlapped by all observations, 180 of which lie within the D<sub>25</sub> ellipse angular diameter of the galaxy. These 236 sources range in X-ray luminosity L<sub>X</sub> from 3.5 x 10<sup>36</sup> erg s<sup>-1</sup> (with 3-sigma upper limit <= 1 x 10<sup>37</sup> erg s<sup>-1</sup>) to ~2 x 10<sup>40</sup> erg s<sup>-1</sup>, including the central nuclear source which has been classified as a LINER. From optical data, 39 X-ray sources have been determined to be coincident with a GC, these sources tend to have high X-ray luminosity, with 10 of these sources exhibiting L<sub>X</sub> > 1 x 10<sup>38</sup> erg s<sup>-1</sup>. From X-ray source photometry, it has been determined that the majority of the 236 point sources that have well-constrained colors have values that are consistent with typical low-mass X-ray binary spectra, with 29 of the sources expected to be background objects from the log N-log S relation. There are 103 sources in this population that exhibit long-term variability, indicating that they are accreting compact objects. Three of these sources have been identified as transient candidates, with a further three possible transients. Spectral variations have also been identified in the majority of the source population, where a diverse range of variability has been identified, indicating that there are many different source classes located within this galaxy. This HEASARC table contains the master source list (Table 3 of the reference paper) and the X-ray properties of the sources in the co-added observations (Table 4 of the reference paper), but not the X-ray properties of the sources in the 6 individual observations (Tables 5-10 of the reference paper). The details of the six individual pointings used in this study, e.g., the Chandra ObsIDs, dates, exposure times and cleaned exposure times, are given in Table 1 of the reference paper, and repeated here: <pre> Obs. No.OBSID Date Exposure (s) Cleaned Exposure (s) 1 4741 2005 Feb 3 37462.0 37264.5 2 7077 2006 Mar 16 110303.8 107736.7 3 7078 2006 Jul 25 51433.2 48076.2 4 7079 2006 Oct 24 105071.7 102504.6 5 7081 2007 Feb 20 110724.0 107564.5 6 7080 2007 Apr 20 55824.8 54837.5 Total Co-added 470819.5 457984.0 </pre> Notes. The pointing OBSID 7181 was taken before OBSID 7080, so to maintain the time sequence of the exposures these observation numbers have been labeled as above in the reference paper. The details of the energy bands and X-ray colors used in this study are given in Table 2 of the reference paper, and repeated here: <pre> Band/Color Energy Range/Definition Broad (B) 0.3-8 keV Soft (S) 0.3-2.5 keV Hard (H) 2.5-8 keV Soft 1 (S1) 0.3-0.9 keV Soft 2 (S2) 0.9-2.5 keV Conventional broad (Bc) 0.5-8 keV Conventional soft (Sc) 0.5-2 keV Conventional hard (Hc) 2-8 keV Hardness ratio HR (Hc-Sc)/(Hc+Sc) X-ray color C21 -log(S2) + log(S1) = log(S1/S2) X-ray color C32 -log(H) + log(S2) = log(S2/H) </pre> This table was created by the HEASARC in April 2009 based on machine-readable versions of Tables 3 and 4 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
NGC 6231 Chandra X-Ray Point Source Catalog
NGC 6231 is a massive young star cluster, near the center of the Sco OB1 association. While its OB members are well studied, its low-mass population has received little attention. In the reference paper, the authors present high-spatial resolution Chandra ACIS-I X-ray data, wherein they detect 1,613 point X-ray sources. Their main aim was to clarify the global properties of NGC 6231 down to low masses through a detailed membership assessment, and to study the cluster stars' spatial distribution, the origin of their X-ray emission, the cluster age and formation history, and its initial mass function. The authors use X-ray data, complemented by optical and IR data, to establish cluster membership. The spatial distribution of different stellar subgroups also provides highly significant constraints on cluster membership, as does the distribution of X-ray hardness. In their study, the authors perform spectral modeling of group-stacked X-ray source spectra. The X-ray properties of the sources detected in the Chandra observations of NGC 6231, and their cross-identifications in the catalogs of Sung, Sana, and Bessell (2013 AJ, 145, 37; hereafter SSB); VPHAS+ (Drew et al., 2014, MNRAS, 440, 2036); and 2MASS (<a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/246">CDS Cat. II/246</a>), and information about membership, H-alpha or IR excess, mass and luminosity are also provided. SSB derive a distance modulus for NGC 6231 of 11.0 (1,585 pc), a reddening E(B - V) = 0.47, and a nearly normal reddening law with R = 3.2. The present authors adopt these values for this work. NGC 6231 was observed twice in X-rays with the ACIS-I detector on-board the Chandra X-ray Observatory on 2005, July 3 to 4 (ObsId 5372) and 16 to 17 (ObsID 6291), respectively. The two pointings share the same center (aimpoint) but were performed with a different roll angle. Effective exposure times for the observations were 76.19 and 44.39 ks, respectively, making the total exposure time 120.58 ks. The data were filtered to retain the energy band 0.3 - 8.0 keV, and the full-field lightcurves were inspected to search for high-background periods, but none were found. Exposure maps were computed using standard CIAO software tasks. To these prepared datasets, the authors applied the source detection software PWDetect, a wavelet-based detection algorithm developed at INAF-Osservatorio Astronomico di Palermo. The PWDetect version used here is a modified one, able to detect sources in combined datasets, thus taking full advantage of the deep total exposure. The detection threshold was chosen such as to yield ten spurious detections in the field of view (FOV), for the given background counts. This is a more relaxed constraint than the more usual limit of one spurious detection per field, but is justified when the lowered threshold allows the detection of more than one hundred additional faint sources, as it was the case here or in the COUP Program's Orion data. This HEASARC table contains the list of 1,613 detected X-ray point sources and information about their optical and IR counterparts, where known. It does not contain the 275 additional candidate cluster members (where their candidacy was based on their having H-alpha or IR excesses) which lack X-ray counterparts and that were also listed in Table B.2 of the reference paper. This table was created by the HEASARC in December 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/596/A82">CDS Catalog J/A+A/596/A82</a> file tableb.dat, which is the merger of tables B.1 (the list of 1,613 X-ray sources) and B.2 (the list of 1,888 optical and near-IR identifications of X-ray sources and of IR- and H-alpha-excess stars) from the reference paper, but excluding the 275 stars listed in the latter whose candidacy was based on their having H-alpha or IR excesses and which lack X-ray counterparts. # This is a service provided by NASA HEASARC .
NGC 1068 Chandra X-Ray Compact Source Catalog
This table contains some of the results from a study of the compact X-ray source population in the Seyfert 2 galaxy NGC 1068, imaged with a 50-ks Chandra observation. The authors find a total of 84 compact sources on the ACIS-S3 chip, of which 66 are located within the 25.0 B-mag/arcsec<sup>2</sup> isophote of the galactic disk of NGC 1068. In the reference paper, the spectra of the 21 X-ray sources with at least 50 counts were modeled with both multicolor disk blackbody and power-law models. The power-law model provides the better description of the spectrum for 18 of these sources. For fainter sources, the spectral index was estimated from the hardness ratio. Five sources have 0.4-8 keV intrinsic luminosities greater than 10<sup>39</sup> ergs s<sup>-1</sup>, assuming that their emission is isotropic and that they are associated with NGC 1068. The authors refer to these sources as intermediate-luminosity X-ray objects (IXOs). If these five sources are X-ray binaries accreting with luminosities that are both sub-Eddington and isotropic, then the implied source masses are >~7 solar masses, and so they are inferred to be black holes. Most of the spectrally modeled sources have spectral shapes similar to Galactic black hole candidates. However, the brightest compact source in NGC 1068 has a spectrum that is much harder than that found in Galactic black hole candidates and other IXOs. The brightest source also shows large amplitude variability on both short-term and long-term timescales, with the count rate possibly decreasing by a factor of 2 in ~2 ks during this Chandra observation, and the source flux decreasing by a factor of 5 between this observation and the grating observations taken just over 9 months later. The ratio of the number of sources with luminosities greater than 2.1 x 10<sup>38</sup> ergs s<sup>-1</sup> in the 0.4-8 keV band to the rate of massive (>5 solar masses) star formation is the same, to within a factor of 2, for NGC 1068, the Antennae, NGC 5194 (the main galaxy in M51), and the Circinus galaxy. This suggests that the rate of production of X-ray binaries per massive star is approximately the same for galaxies with currently active star formation, including "starbursts." The authors were concerned with the study of the discrete X-ray source population in NGC 1068, imaged within the 8.4 arcmin x 8.4 arcmin (35.3 kpc x 35.3 kpc) field of view of the ACIS S3 chip. Images were extracted from the reprocessed level 2 events file in soft (0.4-1.5 keV), hard (1.5-5.0 keV) and full (0.4-5.0 keV) energy bands. The authors used the CIAO program wavdetect to search the images in the three energy bands for discrete sources of X-ray emission. They analyzed the images using wavelet scales in the range from 1 pixel (0.492 arcsec) to 16 pixels (7.87 arcsec), separated by a factor of sqrt(2). The wavelet source detection threshold was set to 10<sup>-6</sup>, which gives approximately one false source for the whole S3 chip. The total number of sources detected by wavdetect in the soft, hard, and full energy band images was 115, 67, and 138, respectively. Each of these sources was examined carefully by eye, and only those 84 sources that appear compact to the eye are included in this source list. This table was created by the HEASARC in August 2015 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/591/138">CDS Catalog J/ApJ/591/138</a> file table1.dat. This is a service provided by NASA HEASARC .
NGC 6530 Chandra Point Source Optical/IR Identifications Catalog
The authors have obtained astrometry and BVI photometry, down to a V magnitude of ~22, of the very young open cluster NGC 6530, from observations taken with the Wide Field Imager (WFI) camera at the MPG/ESO 2.2m Telescope. They have positionally matched their optical catalog with the list of X-ray sources found in a Chandra-ACIS observation of this cluster (Damiani et al. 2004, ApJ, 608, 781: available in Browse both via links from this table and also as the NGC6530CXO table), finding a total of 828 stars in common, 90% of which are pre-main sequence stars in NGC 6530. The data used in this work come from the combination of optical BVI images taken with the WFI camera made on 27-28 July 2000, a 60 ks Chandra ACIS X-ray observation, and public near-infrared data from the All-Sky Catalog of Point Sources of the Two Micron All Sky Survey (2MASS, CDS Cat. <II/24>). The total number of optical sources falling in the Chandra FOV is 8956, while the Damiani et al. (2004, ApJ, 608, 781) Catalog contains 884 X-ray sources, who concluded that at least 90% of the X-ray sources are very probable cluster members. To cross-correlate the X-ray and optical catalogs, the authors used a matching distance of < 4 sigmaX, where sigmaX is the the X-ray positional error, or 1.5", whichever is smaller, after a systematic shift between the X-ray and WFI positions of 0.2" in RA and -0.26" in Dec had been included. This resulted in a number of multiple identifications, among which 4 turned into unique identifications when a reduced distance of 1.5" was used. This finally resulted in 721 single, 44 double, and 3 triple identifications in the optical catalog; in addition, one X-ray source has 4 optical identifications, and another has 6 optical identifications. The total number of X-ray sources with WFI counterparts is therefore 770; of them, only 15 X-ray identified stars come from the Sung et al. (2000, AJ, 120, 333) Catalog and are not in the WFI Catalog. The total number of optical sources with an X-ray counterpart is 828. The agreement between X-ray and WFI optical positions is excellent in most cases, with offsets below 1". This database table was created by the HEASARC in February 2007, based on CDS table J/A+A/430/941/table5.dat This is a service provided by NASA HEASARC .
NGC 2516 Chandra X-Ray Point Source Catalog
The NGC 2516 Chandra X-Ray Point Source Catalog is the result of a comprehensive study of the Chandra X-ray observations of the young open star cluster NGC 2516. The authors have analyzed eight individual Chandra observations, comprising 5 ACIS and 3 HRC-I observations. They have combined these datasets to achieve the greatest sensitivity, reaching down to a threshold level of log f<sub>X</sub> = -14.56 (erg/s/cm<sup>2</sup>), or log L<sub>X</sub> = 28.69 (erg/s) at the 387 pc distance of NGC 2516. Out of 284 X-ray sources detected, 155 are identified with photometric cluster members, with very little ambiguity, another 60 with non-members. There are 4 X-ray sources with two possible optical identifications (one cluster member and one nonmember for each), with no obvious choice between the two candidates. These 4 X-ray sources are listed in this Browse table twice, one for each optical counterpart, hence there are (284 + 4 =) 288 entries. There remain 73 X-ray sources without an optical identification with the authors' optical catalog stars. This Browse table was created by the HEASARC in December 2006, based on CDS table J/ApJ/588/1009, files table4.dat and table5.dat. This is a service provided by NASA HEASARC .
NGC 752 Chandra X-Ray Point Source Catalog
This table provides a list of X-ray sources detected in a ~140 ks Chandra X-ray observation of the open cluster NGC 752. For the sources with 2MASS counterparts, the values of their magnitudes in the J, H and K bands are also given. Very little is known about the evolution of stellar activity between the ages of the Hyades (0.8 Gyr) and the Sun (4.6 Gyr). To gain information on the typical level of coronal activity at a star's intermediate age, the authors have studied the X-ray emission from stars in the 1.9 Gyr-old open cluster NGC 752. They analyzed a ~ 140 ks Chandra observation of NGC 752 and a ~50 ks XMM-Newton observation of the same cluster. They detected 262 X-ray sources in the Chandra data and 145 sources in the XMM-Newton observation. Around 90% of the catalogued cluster members within Chandra's field of view are detected in the X-ray observation. The X-ray luminosity of all observed cluster members (28 stars) and of 11 cluster member candidates was derived. These data indicate that, at an age of 1.9 Gyr, the typical X-ray luminosity L<sub>x</sub> of the cluster members with masses of 0.8 to 1.2 solar masses is 1.3 x 10<sup>28</sup> erg s<sup>-1</sup>, which is approximately a factor of 6 times less intense than that observed in the younger Hyades. Given that L<sub>x</sub> is proportional to the square of a star's rotational rate, the median L<sub>x</sub> of NGC 752 is consistent, for t >= 1 Gyr, with a decaying rate in rotational velocities v<sub>rot</sub> ~ t<sup>-alpha</sup> with alpha ~ 0.75, steeper than the Skumanich relation (alpha ~ 0.5) and significantly steeper than that observed between the Pleiades and the Hyades (where alpha <0.3), suggesting that a change in the rotational regimes of the stellar interiors is taking place at an age of ~ 1 Gyr. The 135 ks observation of NGC 752 was performed by the Chandra ACIS camera on September 29, 2003 starting at 21:11:59 UT. The X-ray source detection was performed on the event list using the Wavelet Transform detection algorithm developed at Palermo Astronomical Observatory PWDETECT, available at <a href="http://oapa.astropa.unipa.it/progetti_ricerca/PWDetect">http://oapa.astropa.unipa.it/progetti_ricerca/PWDetect</a>. Initially, the energy range 0.2 - 10 keV was selected and the threshold for source detection was taken as to ensure a maximum of 1-2 spurious sources per field. 169 sources were detected in this way. The analysis of these sources hardness ratios showed, however, that all the catalogued stars in the field had low hardness ratios, HR < ~ 0.2, where HR is the number of photons in the 2 - 8 keV band over the number in the 0.5 - 2 keV band. Thus, to maximize the detection of stellar sources, PWDETECT was applied to the event list in the energy range from 0.5 - 2 keV. Using a detection threshold which ensures less than 1 spurious source per field leads to the detection of 188 sources, while lowering this threshold to 10 spurious sources per field, allows 262 sources to be identified in this energy range. This is a significant increase (well above the number expected if all the additional sources were spurious), thus the authors retained this list of 262 sources as their final list of sources in the NGC 752 field, with the caveat that ~ 10 sources among them are likely spurious. Note that the existence of ~ 10 spurious sources in the list is not so much of a problem in this context, because cluster members or candidate members are identified by the existence of a visible or near-IR counterpart. The authors searched for 2MASS counterparts to the X-ray sources using the 2MASS Point Source Catalogue (PSC) and a search radius of 3 arcsec and found a counterpart for 43 sources. Searching within the Point Source Reject Table of the 2MASS Extended Mission leads to the further identification of 1 counterpart (source number 87). This table was created by the HEASARC in October 2008 based on the electronic version of Table 6 from the reference paper which was obtained from the CDS website, i.e., their catalog J/A+A/490/113 file table6.dat. This is a service provided by NASA HEASARC .
NGC 3115 Chandra X-Ray Point Source Catalog
This table contains some of the results from an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1 Ms). In total the authors found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2-sigma detection, with 0.3-8 keV luminosity L<sub>X</sub> ~ 10<sup>36</sup> - 10<sup>39</sup> erg s<sup>-1</sup>. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at L<sub>X</sub> >~ 2 x 10<sup>37</sup> erg s<sup>-1</sup>. In order to identify the nature and spectral state of these sources, the authors compared their collective spectral properties based on single-component models (a simple power law or a multicolor disk) with the spectral evolution seen in representative Galactic LMXBs. The authors found that in the L<sub>X</sub> vs. photon index Gamma<sub>PL</sub> and L<sub>X</sub> versus disk temperature kT<sub>MCD</sub> plots, most of their sources fall on a narrow track in which the spectral shape hardens with increasing luminosity below L<sub>X</sub> ~ 7 x 10<sup>37</sup> erg s<sup>-1</sup>, but is relatively constant (Gamma<sub>PL</sub> ~ 1.5 or kT<sub>MCD</sub> ~ 1.5 keV) above this luminosity, which is similar to the spectral evolution of Galactic neutron star (NS) LMXBs in the soft state in the Chandra bandpass. Therefore, the authors identified the track as the NS LMXB soft-state track and suggested sources with L<sub>X</sub> <~ 10<sup>37</sup> erg s<sup>-1</sup> as atolls in the soft state and those with L<sub>X</sub> >~ 10<sup>37</sup> erg s<sup>-1</sup> as Z sources. Ten other sources (five are transients) displayed significantly softer spectra and are probably black hole X-ray binaries in the thermal state. One of them (a persistent source) is in a metal-poor GC. The 11 Chandra observations of NGC 3115 are listed in Table 1 of the reference paper. They were made during three epochs: one in 2001,two in 2010, and nine in 2012. All observations used the imaging array of the AXAF CCD Imaging Spectrometer (ACIS). This table contains the properties of the 482 detected point sources in the merged and single Chandra ACIS observations of NGC 3115 above a 2-sigma threshold and after eliminating a number of spurious sources associated with bright streaks on the ACIS-S1 chip and (in one case) on a CCD edge. 469 of these sources (indicated by values of obs_flag = '0') have a single entry in this table, based on their properties as derived from all of the available Chandra data for that position. There are 13 transient sources (having obs_flag = 'h') for which an additional entry is provided referring to their properties in the "high state", and based on the combination of their high-state observations, as shown in Figures 3(a) - 3(d) in the reference paper. For source number 198, there is a second additional entry provided referring to its properties in the "low state", and based on the combination of its low-state observations, as shown in Figure 3(c) in the reference paper. Thus, there are 496 entries (rows) in this table, i.e., 482 + 13 + 1. This table was created by the HEASARC in August 2015 based on the union of the machine-readable versions of Table 3 (the master source catalog) and Table 4 (the source counts, fluxes and hardness ratios in the merged observations) that were obtained from the ApJ web site. It does not contain the source counts and fluxes in the individual observations which were given in Table 5 of the reference paper. This is a service provided by NASA HEASARC .
NGC 55 Chandra X-Ray Point Source Catalog
This table contains a comprehensive X-ray point source catalog of the SB(s)m galaxy NGC 55, a member of the nearby Sculptor group of galaxies, as part of the Chandra Local Volume Survey. The combined archival observations of this galaxy have an effective exposure time of 56.5 ks. When combined with the catalogs of sources in NGC 2403 and NGC 4214 given in this same reference paper, and the authors' previously published catalogs for NGC 300 (Binder et al. 2012, ApJ, 758, 15) and NGC 404 (Binder et al. 2013, ApJ, 763, 128), the CLVS contains 629 high-significance X-ray sources total down to a limiting unabsorbed luminosity of ~ 5 x 10<sup>35</sup> erg s<sup>-1</sup> in the 0.35-8.0 keV band in each of the five galaxies. In the reference paper, the authors present X-ray hardness ratios, spectral analysis, radial source distributions, and an analysis of the temporal variability for the X-ray sources detected at high significance. To constrain the nature of each X-ray source, they carried out cross-correlations with multi-wavelength data sets. They searched overlapping Hubble Space Telescope observations for optical counterparts to their X-ray detections to provide preliminary classifications for each X-ray source as a likely X-ray binary, background active galactic nucleus, supernova remnant, or foreground star. The authors utilized archival X-ray observations: NGC 55 was observed by the Chandra X-Ray Observatory on 2001 September 11 for 47 ks using the ACIS-I array (Obs. ID 2255), and on 2004 June 29 for 9.5 ks using the ACIS-I array (Obs. ID 4744). The iterative source detection strategy that was used is described in Section 2.3 of Binder et al. (2012, ApJ, 758, 15). ACIS-Extract (AE) was run a final time on the source list that was produces after an initial run of wavdetect followed by several iterations of AE, and the Poisson probability of not being a source (pns) value was computed in each of the following nine energy bands: 0.5 - 8.0, 0.5 - 2.0, 2.0 - 8.0, 0.5 - 1.0, 1.0 - 2.0, 2.0 - 4.0, 4.0 - 8.0, 0.35 - 1.0 or 0.35 - 8.0 keV. To be included in the final NGC 55 catalog, a source was required to have a pns value less than 4 x 10<sup>-6</sup> in any of the nine energy bands. The final CLVS source catalog for NGC 55 contains 154 sources. This table was created by the HEASARC in September 2015 based on machine-readable versions of those parts of Table 5 and 8 from the reference paper which pertained to the 154 high-significance (pns < 4 x 10<sup>-6</sup>) X-ray sources which were detected in NGC 55. It does not include the 76 lower-significance sources in NGC 55 which had 4 x 10<sup>-6</sup> < pns < 1.0 x 10<sup>-3</sup>, some of which are likely to be genuine X-ray sources. This is a service provided by NASA HEASARC .
NGC 300 Chandra X-Ray Point Source Catalog
This table contains the source catalog from a new Chandra ACIS-I observation of the nearby (2.0 Mpc) SA(s)d spiral galaxy NGC 300 which was obtained as part of the Chandra Local Volume Survey (CLVS). This 63-ks exposure covers ~88% of the D<sub>25</sub> isophote (R ~ 6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance down to a limiting unabsorbed 0.35-8 keV luminosity of ~ 10<sup>36</sup> erg/s. Sources were cross-correlated with a previous XMM-Newton catalog, and the authors find 75 "X-ray transient candidate" sources that were detected by one observatory, but not the other. They derive an X-ray scale length of 1.7 +/- 0.2 kpc and a recent star formation rate of 0.12 M<sub>sun</sub>/yr in excellent agreement with optical observations. Deep, multi-color imaging from the Hubble Space Telescope, covering ~ 32% of this Chandra field, was used to search for optical counterparts to the X-ray sources, and the authors have developed a new source classification scheme to determine which sources are likely X-ray binaries, supernova remnants, and background active galactic nucleus candidates. In the reference paper, the authors present the X-ray luminosity functions (XLFs) at different X-ray energies, and find the total NGC 300 X-ray point-source population to be consistent with other late-type galaxies hosting young stellar populations (<~ 50 Myr). They find that the XLF of sources associated with older stellar populations has a steeper slope than the XLF of X-ray sources coinciding with young stellar populations, consistent with theoretical predictions. NGC 300 was observed on 2010 September 25 for 63 ks using ACIS-I during the Chandra X-Ray Observatory Cycle 12, observation ID 12238. The source detection strategy that was used is described in Section 2.3 of the reference paper. ACIS-Extract (AE) was run a final time on the source list that was produces after an initial run of wavdetect followed by several iterations of AE, and the Poisson probability of not being a source (pns) value was computed in each of the following nine energy bands: 0.5 - 8.0, 0.5 - 2.0, 2.0 - 8.0, 0.5 - 1.0, 1.0 - 2.0, 2.0 - 4.0, 4.0 - 8.0, 0.35 - 1.0 and 0.35 - 8.0 keV. To be included in the final NGC 300 catalog, a source was required to have a pns value less than 4 x 10<sup>-6</sup> in any of the nine energy bands; if only the 0.35 - 8 keV band were considered, ~4% of significant sources would have been lost. The final CLVS source catalog for NGC 300 contains 95 sources. This table was initially created by the HEASARC in September 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/758/15/">CDS Catalog J/ApJ/758/15/</a> files table4.dat, table5.dat, table6.dat and table7.dat containing the X-ray properties of the 95 Chandra point sources found in this study. The information on the optical counterparts to (some of) the Chandra X-ray sources and on the X-ray point source classification (presented in Tables 16 and 17, respectively, of the reference paper) is not included herein. It was updated in September 2015 to include the unabsorbed 0.35-8.0 keV energy fluxes (in the parameter herein called b4_flux) from the second reference paper. This is a service provided by NASA HEASARC .
NGC 2264 XMM-Newton X-Ray Point Source Catalog
This table contains (some of) the results from an X-ray imaging survey of the young cluster NGC 2264, carried out with the European Photon Imaging Cameras (EPIC) on board the XMM-Newton spacecraft. XMM-Newton EPIC observations were made separately of the northern and southern portions of NGC 2264 on 2001 March 20 and 2002 March 17 - 18, respectively. Details concerning the two pointings are summarized in Table 1 of the reference paper. The nominal integration time was 42 ks for both observations. The three EPIC cameras were operated in full window mode. To prevent contamination of the X-ray images by the XUV and EUV emission of the optically and UV-bright sources in the field of view, the thick filter was used, which imposes a strong cut-off in the response at the lower energies. The X-ray data are merged with extant optical and near-infrared photometry, spectral classifications, H-alpha emission strengths, and rotation periods to examine the interrelationships between coronal and chromospheric activity, rotation, stellar mass, and internal structure for a statistically significant sample of pre-main-sequence stars. Out of the 316 distinct point-like sources that were detected at >= 3-sigma levels in one or more of six EPIC images, a total of 300 distinct X-ray sources can be identified with optical or near-infrared counterparts. The sources are concentrated within three regions of the cluster: in the vicinity of S Mon, within the large emission/reflection nebulosity southwest of S Mon, and along the broad ridge of molecular gas that extends from the Cone Nebula to the NGC 2264 IRS 2 field. From the extinction-corrected color-magnitude diagram of the cluster, ages and masses for the optically identified X-ray sources are derived. A median age of ~ 2.5 Myr and an apparent age dispersion of ~ 5 Myr are suggested by pre-main-sequence evolutionary models. The X-ray luminosity of the detected sources appears well-correlated with bolometric luminosity, although there is considerable scatter in the relationship. Stellar mass contributes significantly to this dispersion, while isochronal age and rotation do not. X-ray luminosity and mass are well correlated such that L<sub>X</sub> ~ (M/M<sub>solar</sub>)<sup>1.5</sup>, which is similar to the relationship found within the younger Orion Nebula Cluster. No strong evidence is found for a correlation between E(H-K), the near-infrared color excess, and the fractional X-ray luminosity, which suggests that optically thick dust disks have little direct influence on the observed X-ray activity levels. Among the X-ray-detected weak-line T Tauri stars, the fractional X-ray luminosity, L<sub>X</sub>/L<sub>bol</sub>, is moderately well correlated with the fractional H-alpha luminosity, L<sub>H(alpha)</sub>/L<sub>bol</sub>, but only at the 2-sigma level of significance. The cumulative distribution functions for the X-ray luminosities of the X-ray-detected classical and weak-line T Tauri stars within the cluster are comparable, assuming the demarcation between the two classes is at an H-alpha equivalent width of 10 Angstroms. However, if the non-detections in X-rays for the entire sample of H-alpha emitters known within the cluster are taken into account, then the cumulative distribution functions of these two groups are clearly different, such that classical T Tauri stars are underdetected by at least a factor of 2 relative to the weak-line T Tauri stars. Examining a small subsample of X-ray-detected stars that are probable accretors based on the presence of strong H-alpha emission and near-infrared excess, the authors conclude that definitive non-accretors are ~ 1.6 times more X-ray luminous than their accreting counterparts. In agreement with earlier published findings for the Orion Nebula Cluster, the authors find a slight positive correlation (valid at the 2-sigma confidence level) between L<sub>X</sub>/L<sub>bol</sub> and the rotation period in NGC 2264 stars. The lack of a strong anti-correlation between X-ray activity and rotation period in the stellar population of NGC 2264 suggests that either the deeply convective T Tauri stars are rotationally saturated or that the physical mechanism responsible for generating magnetic fields in pre-main-sequence stars is distinct from the one that operates in evolved main-sequence stars. This table was created by the HEASARC in September 2007 based on the electronic version of Table 2 from the reference paper which was obtained from the electronic AJ site. This is a service provided by NASA HEASARC .
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.