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291. EXOSAT TGS Spectra and Lightcurves
ID:
ivo://nasa.heasarc/tgs2
Title:
EXOSAT TGS Spectra and Lightcurves
Short Name:
TGS2
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
Spectra obtained using the EXOSAT transmission grating spectrometer, TGS. There are two databases TGS and TGS2 as follows: <pre> * TGS - the grating spectra averaged over the positive and negative orders * TGS2 - the postive and negative orders kept separate </pre> TGS provides a better overview of the spectrum, and is quicker to use with a spectral fitting program. This is the default that most users will want to use. Once a user has become more expert and want to see, for example, if a subtle feature is present in both halves of the grating spectra, the user can access TGS2. This is a service provided by NASA HEASARC .
292. Extended Chandra Deep Field South 250-ks Improved Point Source Catalog
ID:
ivo://nasa.heasarc/ecdfsnew
Title:
Extended Chandra Deep Field South 250-ks Improved Point Source Catalog
Short Name:
ECDFSNEW
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the improved point-source catalog for the 250-ks Extended Chandra Deep Field-South (E-CDF-S) Survey, implementing a number of recent improvements in Chandra source-cataloguing methodology. For the E-CDF-S, the main catalog (entries from which are indicated with parameter values of source_sample = "Main" in this HEASARC representation) contains 1003 X-ray sources detected with wavdetect at a false-positive probability threshold of 10<sup>-5</sup> that also satisfy a binomial-probability source-selection criterion of P < 0.002. Such an approach maximizes the number of reliable sources detected: a total of 275 main-catalog sources are new compared to the Lehmer et al. (2005, ApJS, 161, 21) E-CDF-S main catalog. The authors also provide an E-CDF-S supplementary catalog that consists of 56 sources (entries from which are indicated with parameter values of source_sample = "Supp" in this HEASARC representation) detected at the same wavdetect threshold and having P of 0.002-0.1 and K<sub>s</sub> <= 22.3 mag counterparts. For all 1059 E-CDF-S sources, including the 318 newly detected ones (these being generally fainter and more obscured), the authors determine X-ray source positions utilizing centroid and matched-filter techniques; they also provide multi-wavelength identifications, apparent magnitudes of counterparts, spectroscopic and/or photometric redshifts, basic source classifications, and estimates of observed active galactic nucleus and galaxy source densities around respective field centers. Simulations show that the E-CDF-S main catalog is highly reliable and reasonably complete. Background and sensitivity analyses indicate that the on-axis mean flux limits reached represent a factor of ~1.5-2.0 improvement over the previous E-CDF-S limit. The 250-ks E-CDF-S is composed of four distinct and contiguous ~ 250-ks Chandra pointings that flank the CDF-S proper, consisting of a total of nine separate observations taken between 2004 February 29 and November 20 (see Lehmer et al., 2005, ApJS, 161, 21 for more details). This table was created by the HEASARC in August 2016 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/224/15">CDS Catalog J/ApJS/224/15</a> files table9.dat (the main source catalog) and table12.dat (the supplementary source catalog). This is a service provided by NASA HEASARC .
293. Extended Chandra Deep Field-South Optical and Near-IR Counterparts
ID:
ivo://nasa.heasarc/ecdfsoid2
Title:
Extended Chandra Deep Field-South Optical and Near-IR Counterparts
Short Name:
ECDFSOID2
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the results of a program to acquire high-quality optical spectra of X-ray sources detected in the Extended-Chandra Deep Field-South (E-CDF-S) and its central 2 Ms area. New spectroscopic redshifts, up to z = 4, are measured for 283 counterparts to Chandra sources with deep exposures (t ~ 2-9 hr per pointing) using multi-slit facilities on both VLT (VIMOS) and Keck (DEIMOS), thus bringing the total number of spectroscopically identified X-ray sources to over 500 in this survey field. Since their new spectroscopic identifications are mainly associated with X-ray sources in the shallower 250 ks coverage, the authors provide a comprehensive catalog of X-ray sources detected in the E-CDF-S including the optical and near-infrared counterparts, determined by a likelihood routine, and redshifts (both spectroscopic and photometric), that incorporate published spectroscopic catalogs, thus resulting in a final sample with a high fraction (80%) of X-ray sources having secure identifications. The authors demonstrate the remarkable coverage of the luminosity-redshift plane now accessible from their data while emphasizing the detection of active galactic nuclei (AGNs) that contribute to the faint end of the luminosity function (L<sub>0.5-8keV</sub> ~ 10<sup>43</sup> - 10<sup>44</sup> erg s<sup>-1</sup>) at 1.5 <~ z <~ 3, including those with and without broad emission lines. This redshift catalog includes 17 type-2 QSOs at 1 <~ z <~ 3.5 that significantly increases (doubles) such samples. Based on thei deepest (9 hr) VLT/VIMOS observation, the authors identify "elusive" optically faint galaxies (R<sub>mag</sub> ~ 25) at z ~ 2 - 3 based upon the detection of interstellar absorption lines (e.g., O II+Si IV, C II], C IV); in their paper, they highlight one such case, an absorption-line galaxy at z = 3.208 having no obvious signs of an AGN in its optical spectrum. In addition, they determine accurate distances to eight galaxy groups with extended X-ray emission detected both by Chandra and XMM-Newton. This online catalog was created by the HEASARC in November 2010 based on a machine-readable version of Table 4 from the paper which was obtained from the ApJ website. This is a service provided by NASA HEASARC .
294. Extended Chandra Deep Field-South Survey Optical Identifications Catalog
ID:
ivo://nasa.heasarc/ecdfsoid
Title:
Extended Chandra Deep Field-South Survey Optical Identifications Catalog
Short Name:
ECDFSOID
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the first results of the authors' optical spectroscopy program aimed to provide redshifts and identifications for the X-ray sources in the Extended Chandra Deep Field South (ECDFS). A total of 339 sources (listed herein) were targeted using the IMACS spectrograph at the Magellan telescopes and the VIMOS spectrograph at the VLT. The authors have measured redshifts for 186 X-ray sources, including archival data and a literature search. They find that the active galactic nucleus (AGN) host galaxies have on average redder rest-frame optical colors than nonactive galaxies, and that they live mostly in the "green valley." The dependence of the fraction of AGNs that are obscured on both luminosity and redshift is confirmed at high significance and the observed AGN spatial density is compared with the expectations from existing luminosity functions. These AGNs show a significant difference in the mid-IR to X-ray flux ratio for obscured and unobscured AGNs, which can be explained by the effects of dust self-absorption on the former. This difference is larger for lower luminosity sources, which is consistent with the dust opening angle depending on AGN luminosity. This table was created by the HEASARC in April 2009 based on the electronic version of Table 2 from the Treister et al. (2009) paper obtained from the ApJ web site, except for the source positions which were taken from Virani et al. (2006). The full table from the latter paper is also available in Browse (the ECDFSCXO table). This is a service provided by NASA HEASARC .
295. Extended Chandra Deep Field-South X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/ecdfscxo
Title:
Extended Chandra Deep Field-South X-Ray Point Source Catalog
Short Name:
ECDFSCXO
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Extended Chandra Deep Field-South (ECDFS) survey consists of four Chandra X-Ray Observatory (CXO) ACIS-I pointings and covers ~1100 arcmin<sup>2</sup> (~0.3 deg<sup>2</sup>) centered on the original CDF-S field to a depth of approximately 228 ks. This is the largest Chandra survey ever conducted at such depth, and only one XMM-Newton survey reaches a lower flux limit in the hard 2.0-8.0 keV band. The authors detect 651 unique sources: 587 using a conservative source-detection threshold (identified by source_type = 'P' for primary source) and 64 (identified by source_type = 'S' for secondary source) using a lower source-detection threshold. These are combined in this HEASARC representation but were presented as two separate catalogs (Table 4 contained the primary sources, and Table 5 the secondary sources) in the original reference paper. Of the 651 total sources, 561 are detected in the full 0.5-8.0 keV band, 529 in the soft 0.5-2.0 keV band, and 335 in the hard 2.0-8.0 keV band. For point sources near the aim point, the limiting fluxes are approximately 1.7 x 10<sup>-16</sup> and 3.9 x 10<sup>-16</sup> ergs/cm<sup>2</sup>/s in the 0.5-2.0 and 2.0-8.0 keV bands, respectively. In their paper, the authors present the differential and cumulative flux distributions, which are in good agreement with the number counts from previous deep X-ray surveys and with the predictions from an active galactic nucleus (AGN) population synthesis model that can explain the X-ray background. In general, fainter sources have harder X-ray spectra, consistent with the hypothesis that these sources are mainly obscured AGNs. All nine observations of the ECDFS survey field were conducted with the Advanced CCD Imaging Spectrometer (ACIS) on board Chandra as part of the approved guest observer program in Cycle 5. Notice that Lehmer et al. (2005, ApJS, 161, 21) conducted a somewhat different analysis on these same data and obtained similar, but not identical results, e.g., Lehmer et al. found 809 total X-ray sources compared to 651 in the present table. This table was created by the HEASARC in April 2009 based on the electronic versions of Tables 4 and 5 from the paper which were obtained from the CDS (their catalog J/AJ/131/2373 files table4.dat and table5.dat). This is a service provided by NASA HEASARC .
296. Extragalactic Radio Sources
ID:
ivo://nasa.heasarc/kuehr
Title:
Extragalactic Radio Sources
Short Name:
Kuehr
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This catalog is a compilation of 518 extragalactic radio sources with flux densities greater than 1 Jy at 5 GHz. It contains sources from the NRAO-MPI 5-GHz Strong Source Surveys and from re-observation at 5 GHz of sources found in the Parkes 2.7-GHz surveys. All sources were found in 9.811 sr covered by the two surveys. This is essentially the whole sky, excluding the galactic plane (latitudes less than 10 degrees) and the Magellanic Clouds. The catalog includes radio flux densities, radio positions, object classes, visual magnitudes, redshifts, and spectral indices. One duplicate entry was removed from the HEASARC implementation of this catalog in June 2019. This is a service provided by NASA HEASARC .
297. Extrasolar Planets Encyclopedia
ID:
ivo://nasa.heasarc/exoplanets
Title:
Extrasolar Planets Encyclopedia
Short Name:
EXOPLANETS
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Extrasolar Planets Encyclopedia is a working tool, providing all the latest detections and data that have been announced by professional astronomers, Which is intended to be used to facilitate progress in exoplanetology. Ultimately, researchers willing to make a quantitative, scientific use of the catalog can make their own judgement on the likelihood of the data and the detections. The stellar data (positions, distances, V and other magnitudes, mass, metallicities etc) are taken from Simbad or from professional papers on exoplanets. Ongoing large extrasolar planets ('exoplanets') projects include: <pre> Anglo-Australian Planet Search <<a href="http://www.phys.unsw.edu.au/~cgt/planet/AAPS_Home.html">http://www.phys.unsw.edu.au/~cgt/planet/AAPS_Home.html</a>> California & Carnegie Planet Search <<a href="http://exoplanets.org/">http://exoplanets.org/</a>> Geneva Extrasolar Planet Search Programmes <<a href="http://obswww.unige.ch/~udry/planet/planet.html">http://obswww.unige.ch/~udry/planet/planet.html</a>> Transatlantic Exoplanet Survey <<a href="http://www.astro.caltech.edu/~ftod/tres/tres.html">http://www.astro.caltech.edu/~ftod/tres/tres.html</a>> University of Texas - Dept. of Astronomy <<a href="http://www.as.utexas.edu/astronomy/research/ss.html">http://www.as.utexas.edu/astronomy/research/ss.html</a>> </pre> This table is based on the VOTable format of the catalog obtained from the Extrasolar Planets Encyclopaedia website at <a href="http://exoplanet.eu/">http://exoplanet.eu/</a>. It is maintained by Jean Schneider and is updated on a frequent basis, as needed. This is a service provided by NASA HEASARC .
298. Extremely Luminous X-Ray Source Candidates Catalog
ID:
ivo://nasa.heasarc/vlulxcat
Title:
Extremely Luminous X-Ray Source Candidates Catalog
Short Name:
VLULXCAT
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
Using Chandra archive data, the authors conducted a thorough survey of luminous X-ray sources. They directly analyzed about 9400 Chandra ACIS observations and cross-correlated the detected X-ray sources with 77,000 galaxies within a distance of 250 Mpc. The final catalog includes 119 unique luminous X-ray source candidates with L<sub>X</sub> > 3 x 10<sup>40</sup> erg/s from 93 galaxies or 41 HLX candidates with L<sub>X</sub> > 1 x 10<sup>41</sup> erg/s from 35 galaxies. The authors derive a moderate contamination rate due to foreground or background sources. In the reference paper, they also cross-correlate the catalog with FIRST, perform variability and periodicity tests, and analyze one HLX candidate in particular. This catalog could be a starting point to perform follow-up observations. In order to know whether an X-ray source falls within a particular galaxy, for each galaxy, the authors collected its center's RA, Dec, distance, and D<sub>25</sub> isophotal info, which includes major axis length, minor axis length, and the position angle of the major axis from the PGC2003 Catalog (Paturel et al. 2003, A&A, 412, 45), which includes the full RC3 catalog and has all of the necessary parameters except for distance. The authors restricted the minimum major axis length to be 10 arcseconds, and collected their distances from NED as much as possible. Their final sample includes 77,000 galaxies within 250 Mpc. The authors used all of the Chandra ACIS data in TE mode that were released before 2014, which includes 9400 ObsIDs. A roughly linear relation between the flux and count rate derived by PIMMS 4.6b was established assuming a power-law spectral shape and galactic foreground extinction (Kalberla et al. 2005, A&A, 440, 775). Any source with a PIMMS luminosity larger than 5 x 10<sup>39</sup> erg s<sup>-1</sup> would be recalculated by the CIAO script model flux assuming a power-law index of 1.7 in the 0.3 - 8.0 keV energy band. After the recalculation, 1,809 X-ray sources with L<sub>x</sub> > 3 x 10<sup>40</sup> erg s<sup>-1</sup> falling within 640 D<sub>25</sub> contours covered by 905 ObsIDs were picked out. A large fraction of the 1,809 sources are galactic nuclei and some of them are repeated. Only off-nuclear sources are considered in this paper. In addition, the centers of the galaxies given by PGC2003 are not necessarily precise and the specific environments of the 1,809 sources are different. Therefore, the authors visually checked the Chandra and DSS images simultaneously, since two-band inspection can help to exclude the nuclear sources, bright knots, and extended sources. X-ray sources with clear DSS features would be dropped because, for a source with a visual magnitude <20 and a distance >30 Mpc, its absolute magnitude would be brighter than -12.4, which is beyond the limit of the brightest star clusters. This table was created by the HEASARC in February 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/222/12">CDS Catalog J/ApJS/222/12</a> file table1.dat, the list of very luminous X-ray source candidates found within the D<sub>25</sub> ellipses of Chandra ACIS-observed PGC2003 galaxies lying within 250 Mpc. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
299. Extremely Red Objects XMM-Newton Survey Catalog
ID:
ivo://nasa.heasarc/erosxmm
Title:
Extremely Red Objects XMM-Newton Survey Catalog
Short Name:
EROSXMM
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the results of a deep (about 80 ks) XMM-Newton survey of the largest sample of near-infrared-selected Extremely Red Objects (R-K > 5) available to date to K<sub>s</sub> < ~19.2. At the relatively bright X-ray fluxes ((F(2-10 keV) >~ 4 x 10<sup>-15</sup> erg cm<sup>-2</sup> s<sup>-1</sup>) and near-infrared magnitude probed by the present observations, the fraction of AGN (i.e. X-ray detected) among the ERO population is small (~3.5%); conversely, the fraction of EROs among hard X-ray selected sources is much higher (~20%). The X-ray properties of the 9 EROs detected in this XMM-Newton observation indicate absorption in excess of 10<sup>22</sup> cm<sup>-2</sup> in a large fraction of them. The X-ray, optical and near-infrared properties of those X-ray selected EROs with a spectroscopic or photometric redshift nicely match those expected for type 2 quasars, the high-luminosity, high-redshift obscured AGNs predicted in baseline XRB synthesis models. A close correlation is detected between X-ray and K-band fluxes. This table contains the X-ray and optical information for the sources detected in the sum of 3 separate XMM-Newton observations of a field centered on 14 49 25, +09 00 13 (J2000.0 RA and Dec) known as the "Daddi" field (Daddi et al. 2000, A&A, 361, 535) in which 257 EROs are known to be present. The data from all 3 EPIC instruments (PN, MOS1 and MOS2) obtained in the 3 observations was combined, yielding a total exposure time for the PN of ~82 ks, and for the MOS instruments of ~78 ks. The X-ray hardness ratio (HR) and the optical to near-infrared color (R and K magnitudes) are reported for all the detected X-ray sources and their counterparts, along with the reliability of the X-ray to optical or near-infrared associations as measured by the likelihood ratios, LR(R) and LR(K). This table lists data for the 111 proposed optical/infrared counterparts for the 97 detected X-ray sources, i.e., X-ray sources with more than one possible optical/IR counterpart will have multiple entries in this table, one for each counterpart, as follows: 73 X-ray sources have secure optical/near-IR counterparts (counterpart_status=1), 7 X-ray sources have 2 possible 'likely' counterparts, and 1 X-ray source has 3 such counterparts (counterpart_status=2), 6 X-ray sources have only low-likelihood counterparts all of which lie outside the 3" matching radii (counterpart_status=3), and the remaining 9 X-ray sources lack optical and infrared photometry (counterpart_status=4). This table was created by the HEASARC in February 2007 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/432/69">CDS Catalog J/A+A/432/69</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC .
300. Faint Images of the Radio Sky at Twenty cm (FIRST)
ID:
ivo://nasa.heasarc/first
Title:
Faint Images of the Radio Sky at Twenty cm (FIRST)
Short Name:
FIRST
Date:
25 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This catalog comprises the Faint Images of the Radio Sky at Twenty cm (FIRST) Survey. The FIRST survey began in 1993, and covers the north and south Galactic caps. The present 14Dec17 version is derived from the 1993 through 2011 observations. The catalog covers a total of about 10,575 square degrees of sky (8,444 square degrees in the north Galactic cap and 2,131 square degrees in the south Galactic cap). See the coverage maps at <a href="http://sundog.stsci.edu/first/catalogs/readme_14dec17.html#coverage">http://sundog.stsci.edu/first/catalogs/readme_14dec17.html#coverage</a> for more details of the area covered. Both the northern and southern areas were chosen to coincide approximately with the area covered by the Sloan Digital Sky Survey (SDSS). The catalog is identical to the previous version of the catalog (14Mar04) except that it has more accurate data on which sources are not covered by the SDSS DR10 catalog. Approximately 1000 sources that were indicated as covered by DR10 in the previous version are now correctly marked as not covered. The source list, radio fluxes, etc., are all the same as the 14Mar04 version. In this version of the catalog, images taken in the the new EVLA configuration have been re-reduced using shallower CLEAN thresholds in order to reduce the "CLEAN bias" in those images. Also, the EVLA images are not co-added with older VLA images to avoid problems resulting from the different frequencies and noise properties of the configurations. That leads to small gaps in the sky coverage at boundaries between the EVLA and VLA regions. As a result, the area covered by this release of the catalog is about 60 square degrees smaller than the earlier release of the catalog (13Jun05), and the total number of sources is reduced by nearly 25,000. The previous version of the catalog does have sources in the overlap regions, but their flux densities are considered unreliable due to calibration errors. The flux densities should be more accurate in this catalog, biases are smaller, and the incidence of spurious sources is also reduced. Over most of the survey area, the detection limit is 1 mJy. A region along the equatorial strip (RA = 21.3 to 3.3 hrs, Dec = -1 to 1 deg) has a deeper detection threshold because two epochs of observation were combined. The typical detection threshold in this region is 0.75 mJy. There are approximately 4,500 sources below the 1 mJy threshold used for most previous versions of the catalog. The format of this catalog is the same as releases since 13Jun05 but differs from earlier versions of the catalog. It contains two parameters which give information on the epoch of observation for each source (called mean_epoch and rms_epoch in this HEASARC version) which are described below. The P(S) parameter (called sidelobe_prob herein), which indicates the probability that the source is a sidelobe, replaces the previous binary sidelobe flag column. The parameters sdss_matches, sdss_first_offset, sdss_imag, sdss_class, twomass_matches, twomass_first_offset and twomass_kmag give information on counterparts to the FIRST source in the SDSS DR10 catalog and the 2MASS catalog, respectively. Other catalog parameters are common with FIRST catalog releases extending back over the past decade. The co-added images are available online: see the FIRST page at <a href="http://sundog.stsci.edu/first/images.html">http://sundog.stsci.edu/first/images.html</a> for details. The source catalog presented here is derived from the images. Data for the FIRST survey were collected in all VLA B-configurations from Spring 1993 through Spring 2004. For all data collected for the FIRST project, the raw u-v visibility data are placed in the VLA public archive on the day they are taken, and are available for use without restriction. Additional data in the southern Galactic cap were acquired in Spring 2009 and Spring 2011. The VLA was in a hybrid condition in 2009, with some new EVLA receivers and some old VLA receivers. The characteristics of those images are slightly different from the older data, but for most purposes they should be equivalent. In 2011 the EVLA receivers were available with an early version of the new EVLA data system, so there are a number of differences from the old data: <pre> Date Frequencies Bandpass Integration Before 2011 1365, 1435 MHz 2x7 3-MHz channels 180 seconds 2011 1335, 1730 MHz 2x64 2-MHz channels 60 seconds </pre> Note particularly the frequency difference between the new and older data. The new data are in co-added fields with names ending with 'S' (and later letters in the alphabet) and are found entirely in the south Galactic cap. This table was last updated by the HEASARC in May 2015 based on the file: <a href="http://sundog.stsci.edu/first/catalogs/catalog_14dec17.bin.gz">http://sundog.stsci.edu/first/catalogs/catalog_14dec17.bin.gz</a> which contains the 17 December 2014 version of the FIRST Source Catalog. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .