- ID:
- ivo://nasa.heasarc/lofhatlas
- Title:
- LOFAR Radio Catalog of Herschel-ATLAS North Galactic Pole Field
- Short Name:
- LOFHATLAS
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results of Low-Frequency Array (LOFAR) High-Band Array (HBA) observations of the Herschel-ATLAS North Galactic Pole (NGP) survey area. The survey the authors carried out, consisting of four pointings covering around 142 deg<sup>2</sup> of sky in the frequency range 126-173 MHz, does not provide uniform noise coverage but otherwise is representative of the quality of data to be expected in the planned LOFAR wide-area surveys, and has been reduced using recently developed 'facet calibration' methods at a resolution approaching the full resolution of the data sets (~10 x 6 arcsec) and an rms off-source noise that ranges from 100 µJy beam<sup>-1</sup> in the center of the best fields to around 2 mJy/beam at the furthest extent of their imaging. In the reference paper, the authors describe the imaging, cataloguing and source identification processes, and present some initial science results based on a 5-sigma source catalog. These include (i) an initial look at the radio/far-infrared correlation at 150 MHz, showing that many Herschel sources are not yet detected by LOFAR; (ii) number counts at 150 MHz, including, for the first time, observational constraints on the numbers of star-forming galaxies; (iii) the 150-MHz luminosity functions for active and star-forming galaxies, which agree well with determinations at higher frequencies at low redshift, and show strong redshift evolution of the star-forming population; and (iv) some discussion of the implications of these observations for studies of radio galaxy life cycles. The NGP field was observed in four separate pointings, chosen to maximize the area of sky covered, with the LOFAR HBA as part of the Surveys Key Science project. These observations used the HBA_DUAL_INNER mode, meaning that the station beams of core and remote stations roughly matched each other and giving the widest possible field of view. The first observation, which was made early on in LOFAR operations, was of slightly longer duration (~10 h) than the others (~8 h). International stations were included in some of the observations in 2014 but were not used in any of the authors' analysis, which uses only the Dutch array. The author were interested in imaging in several separate frequency ranges (which are referred to hereafter as 'spectral windows'), since they wanted to be able to measure in-band spectral indices for detected sources. In addition, facet calibrating in different spectral windows could be done in parallel, speeding the processing up considerably. Accordingly, they chose to facet calibrate with six spectral windows, each made up of four bands and thus containing about 8 MHz of bandwidth: <pre> Spectral Nominal Frequency Frequency Range Window (MHz) (MHz) 1 130 126 - 134 2 138 134 - 142 3 146 142 - 150 4 154 150 - 158 5 161 158 - 166 6 169 166 - 173 </pre> The final source catalog was made by combining the four per-field catalogs. Ideally, the authors would have combined the images of each field and done source finding on a mosaicked image, but this proved computationally intractable given the very large image cubes that result from having six spectral windows. They therefore merged the catalogs by identifying the areas of sky where there is overlap between the fields and choosing those sources which are measured from the region with the best rms values. This should ensure that there are no duplicate sources in the final catalog. The final master catalogue contains 17,132 sources and is derived from images covering a total of 142.7 deg<sup>2</sup> of independently imaged sky, with widely varying sensitivity. Total HBA-band (150-MHz) flux densities of catalogued sources detected using the PYBDSM software and a 5-sigma detection threshold range from a few hundred µJy to 20 Jy, with a median of 10 mJy. The authors examined all sources in the initial master catalog for associations with sources in other surveys, for rejection as artifacts, and for optical identifications, as described in detail in Section 3.5 of the reference paper. The final outcomes of this process were (a) an associated, artifact-free catalog of 15,292 sources, all of which the authors believe to be real physical objects which is contained in the present HEASARC table, and (b) a catalog of 6,227 objects with plausible, single optical identifications with Sloan Digital Sky Survey (SDSS) sources, representing an identification fraction of just over 40 per cent. (Note that around 50 sources with more than one equally plausible optical identification are excluded from this catalog; further observation would be required to disambiguate these sources). This table was created by the HEASARC in April 2018, based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/462/1910">CDS Catalog J/MNRAS/462/1910</a> file tablea1.dat. This is a service provided by NASA HEASARC .
Number of results to display per page
Search Results
- ID:
- ivo://nasa.heasarc/lorcat
- Title:
- Low-Frequency Radio Catalog of Flat-Spectrum Sources
- Short Name:
- LORCAT
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- A well-known property of the gamma-ray sources detected by Cos-B in the 1970s, by the Compton Gamma-Ray Observatory in the 1990s, and recently by the Fermi Gamma-ray Observatory is the presence of radio counterparts, particularly for those associated with extragalactic objects. This observational evidence is the basis of the radio/gamma-ray connection established for the class of active galactic nuclei known as blazars. In particular, the main spectral property of the radio counterparts associated with gamma-ray blazars is that they show a flat spectrum in the GHz frequency range. The authors' recent analysis dedicated to search for blazar-like candidates as potential counterparts for the unidentified gamma-ray sources allowed them to extend the radio/gamma-ray connection in the MHz regime. They also showed that blazars below 1 GHz maintain flat radio spectra. Thus, on the basis of these new results, the authors have assembled a low-frequency radio catalog of flat-spectrum sources built by combining the radio observations of the Westerbork Northern Sky Survey (WENSS) and of the Westerbork in the southern hemisphere (WISH) catalogs with those of the NRAO Very Large Array Sky survey (NVSS). This catalog could be used in the future to search for new, unknown blazar-like counterparts of gamma-ray sources. First, the authors found NVSS counterparts of Westerbork Synthesis Radio Telescope (WSRT) radio sources, and then they selected flat-spectrum radio sources according to a new spectral criterion, specifically defined for radio observations performed below 1 GHz. In their paper, they also describe the main properties of the catalog listing 28,358 radio sources with spectral indices between 1400 and 325/352 MHz between -1.0 and +0.4, and their log N - log S distributions. Finally, a comparison with the Green Bank 6 cm radio source catalog was performed so as to investigate the spectral shape of the low-frequency flat-spectrum radio sources at higher frequencies. This table was created by the HEASARC in July 2014 based on a machine-readable version of Table 1 from the reference paper which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lmxbcat
- Title:
- Low-Mass X-Ray Binary Catalog (4th Edition, 2007)
- Short Name:
- LMXB
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This is the Fourth Edition of the Catalog of Low-mass X-ray Binaries (LMXBs) in the Galaxy and the Magellanic Clouds. The catalog has a companion catalog of high-mass X-ray binaries (HMXBs) which is called HMXBCAT in the HEASARC database system). The catalog contains source name(s), coordinates, X-ray flux, system parameters, and stellar parameters of the components and other characteristic properties of 187 low-mass X-ray binaries, together with references to a comprehensive selection of the relevant literature. The aim of this catalog is to provide some basic information on the X-ray sources and their counterparts in other wavelength ranges (gamma-rays, UV, optical, IR, and radio). Some sources, however, are only tentatively identified as low-mass X-ray binaries on the basis of their X-ray properties being similar to the known low-mass X-ray binaries. Further identification in other wavelength bands is needed to finally determine the nature of these sources. In cases where there is some doubt about the low-mass nature of the X-ray binary, this is mentioned. Literature published before 1 October 2006 has, as far as possible, been taken into account. This online catalog was created by the HEASARC in September 2007 based on machine-readable tables obtained from the ADC/CDS data centers (their catalog J/A+A/469/807, tables lmxb.dat and lmxbnote.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lupus3xmm
- Title:
- Lupus 3 SFR XMM-Newton X-Ray Point Source Catalog
- Short Name:
- LUPUS3XMM
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the analysis results of an XMM-Newton observation of the Lupus 3 region that contains a high proportion of young low-mass (< 0.3 solar masses) T Tauri stars in the Lupus star-forming complex. The observation had a ~22-ks effective exposure in the pn and MOS cameras. The detection of X-ray sources in 0.5 - 4.5 keV images of the Lupus 3 core was performed using the standard source detection method in the XMM-Newton Science Analysis Software (SAS). 102 candidate X-ray sources were detected with a likelihood threshold of >= 12 (corresponding to 4.4 sigma in Gaussian statistics) in the 30-arcmin diameter field-of-view of the EPIC cameras, of which 25 have visible or near-IR counterparts within the adopted 4" correlation radius for each X-ray source that were known to be pre-main sequence stars. Their X-ray luminosities range from 3 x 10<sup>28</sup> to 3 x 10<sup>30</sup> erg/s. This table gives the list of X-ray sources detected in the core of the Lupus 3 region with the EPIC camera on-board XMM-Newton, except that the X-ray source associated with the star HR 6000 (the nominal target of the XMM-Newton observation of the original PI) has been excluded. Additional information on the optical and IR counterparts of 25 of the X-ray sources, and on the X-ray spectra, is available in the reference paper. This table was created by the HEASARC in Match 2007 based on CDS table J/A+A/454/595 file table6.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/l1641ioxmm
- Title:
- Lynds 1641 and iota Ori Region XMM-Newton X-Ray Point Source Catalog
- Short Name:
- L1641IOXMM
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from an XMM-Newton and Spitzer survey of the part of the Orion A cloud south of the Orion Nebula, the 'Survey of Orion A with XMM-Newton and Spitzer (SOXS)'. The goal of SOXS is to detect the relatively bright X-ray sources in the Orion A cloud and complete the census of more evolved YSOs in this region. These stars represent a sample of cloud members chosen with minimal a priori bias toward their IR properties. This XMM-Newton survey includes the Lynds 1641 (L1641) dark cloud, a region of the Orion A cloud with very few massive stars and hence a relatively low ambient UV flux, and the region around the O9 III star iota Orionis. In addition to proprietary data, the authors used archival XMM data of the Orion Nebula Cluster (ONC) to extend their analysis to a major fraction of the Orion A cloud. They have detected 1060 X-ray sources with more than 4.5-sigma significance in L1641 and the iota Ori region. About 94% of the sources have Two Micron All Sky Survey (2MASS) and Spitzer counterparts, 204 and 23 being Class II and Class I or protostar objects, respectively. In addition, the authors have identified 489 X-ray sources as counterparts to Class III candidates, given they are bright in X-rays and appear as normal photospheres at mid-IR wavelengths. The remaining 205 X-ray sources are likely distant active galactic nuclei (AGN) or other galactic sources not related to Orion A. The authors find that Class III candidates appear more concentrated in two main clusters in L1641. The first cluster of Class III stars is found toward the northern part of L1641, concentrated around iota Ori. The stars in this cluster are more evolved than those in the Orion Nebula. The authors estimate a distance of 300-320 pc for this cluster showing that it is in the foreground of the Orion A cloud. Another cluster rich in Class III stars is located in L1641 South and appears to be a slightly older cluster embedded in the Orion A cloud. Furthermore, other evolved Class III stars are found north of the ONC toward NGC 1977. The SOXS survey is composed of seven specifically proposed ~ 50 ks XMM-Newton fields, south of the ONC, to which the authors added four archival fields in the same region. The archival fields are centered on iota Orionis, V380 Ori, and V883 Ori, respectively (see Fig. 1 and Table 1 of the reference paper for more details of the X-ray observations). This HEASARC table contains the contents of Table 2 (1060 X-ray detected sources in the fields S1 - S10 listed in Table 1 of the reference paper), Table 3 (best-fit spectral parameters for the 232 brightest of these X-ray sources) and Table 4 (list of 1041 IR counterparts to the X-ray sources) from the reference paper. Some X-ray sources have no identified counterparts (16 of them in fact lie outside of the FOV of the Spitzer observations), most have a single counterpart, and a small number have 2 or even 3 IR counterparts within the 5 arcseconds matching radius used. For X-ray sources with more than 1 IR counterpart, we have added entries for the additional counterparts (71 in total), repeating the X-ray information in such cases. Thus, this HEASARC table contains 1131 (1060 + 71) entries corresponding to the 1060 X-ray source detections. To make its contents easier to visualize, the HEASARC has added a a parameter ir_match which lists the counterpart number for the entry: If there is no identified IR counterpart, ir_match is set to 0, for the first listed IR counterpart to 1, for the second and third, to 2 and 3, respectively. Thus, if the user wants to reduce the table back to a pure list of X-ray sources and their primary IR counterparts, they should search the table selecting ir_match < 2. This table was created by the HEASARC in August 2013 based on the electronic versions of Tables 2 and 3 from the original reference paper (2013ApJ...768...99P) and Table 4 from the erratum (2013ApJ...773...80P), which were all obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lbn
- Title:
- Lynds Catalog of Bright Nebulae
- Short Name:
- Lynds(Bright)
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Lynds' Catalog of Bright Nebulae lists the coordinates of the center of the cloud, the dimensions of the nebulae as measured on the photograph on which it appeared at its brightest, the area of nebulosity in square degrees, color as compared between the blue and red Palomar plates, a brightness index on a scale from 1 to 6, an identification number that indicates the complexity of the nebulosity, and a cross reference to NGC (Cat. <VII.1>), Index Catalogue (IC), Sharpless (1959) Catalogue of HII Regions (Cat. <VII/20>), Cederblad (1956) Catalogue of Diffuse Galactic Nebulae, and Dorschner and Gurtler (1963). This database originates from the NASA/ADC CD-ROM "Selected Astronomical Catalogs Vol. 1", dated 09-July-1992. The CDS made several corrections to this and added the LBN sequence number. The current HEASARC version of this table was revised in February 2001 and is based on the CDS version. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ldn
- Title:
- Lynds Catalog of Dark Nebulae
- Short Name:
- Lynds(Dark)
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog is an updated version of the original version of the Lynds' Catalog of Dark Nebulae that was published in 1962. The catalog was based on a study of the red and blue prints of the National Geographic - Palomar Observatory Sky Atlas. The catalog contains positions for the centers of dark nebulae or clouds found by Lynds, values for the cloud sizes in square degrees, visual estimates of their opacity, and cross-identifications to Barnard Objects which are associated with the tabulated clouds. This HEASARC version of the LDN Catalog was created in June 1997. It was derived from <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/7A">CDS Catalog VII/7A</a> obtained from <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/7A/">https://cdsarc.cds.unistra.fr/ftp/cats/VII/7A/</a>. Please refer to the CDS <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/7A/ReadMe">"Historical Notes"</a> for details regarding the lineage of this version. Additional information provided in the HEASARC documentation was taken from the original published version of this catalog. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lyngaclust
- Title:
- Lynga Open Clusters Catalog
- Short Name:
- LyngaOpenCl
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This is a catalog of open cluster data, as compiled by Gosta Lynga, Lund Observatory. The aim of this catalog is to give salient data for all known open star clusters in our galaxy. As far as possible only published data values have been quoted; for some of the parameters, these values have been slected from references which can be obtained from the HEASARC. This data in part results from the merging of the data resulting from a joint project between K. Janes, C. Duke and Lynga, herein refered to as JDL data. The aim of that project was to discuss properties of the open cluster system by using existing data and by taking their accuracy into proper regard. Thus the data were assessed, mostly by Janes, weight assigned and weighted mean values derived of reddenings, turn-off colors and distances. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/macs
- Title:
- Magellanic Catalog of Stars
- Short Name:
- MACS
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Magellanic Catalogue of Stars (MACS) is based on scans of ESO Schmidt plates and contains about 244,000 stars covering large areas around the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). The positions refer to the FK5 system via the PPM Catalog. A comparison of positions from different plates shows internal errors at a level of 0.15 to o.23 arcseconds; the positional accuracy is estimated to be better than 0.5 arcseconds for 99% of the stars. The limiting blue magnitude of the MACS is less than 16.5 magnitudes, but the catalog is not complete to this level, as only those stars are included which are undisturbed by close neighbors as verified by visual (interactive) screening (in order to obtain a clean astrometric reference). This database table was created at the HEASARC in June 1998 based on the ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/I/221">CDS Catalog I/221</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/maghmxbcat
- Title:
- Magellanic Clouds High-Mass X-Ray Binaries Catalog
- Short Name:
- MCHMXRB
- Date:
- 14 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains a catalog of high-mass X-ray binaries (HMXBs) in the Small and Large Magellanic Clouds (SMC and LMC). The catalog lists source name(s), coordinates, apparent magnitudes, orbital parameters, and X-ray luminosities for 128 HMXBs, together with the stellar parameters of the components, other characteristic properties and a comprehensive selection of the relevant literature. The aim of this catalog is to provide easy access to the basic information on the X-ray sources and their counterparts in other wavelength ranges (UV, optical, IR, radio). Most of the sources have been identified as Be/X-ray binaries. Some sources, however, are only tentatively identified as HMXBs on the basis of a transient character and/or a hard X-ray spectrum. Further identification in other wavelength bands is needed to finally determine the nature of these sources. In cases where there is some doubt about the high-mass nature of the X-ray binary this is mentioned. Literature published before 1 May 2005 has, as far as possible, been taken into account. Information on the numbers used to code references is available at <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/442/1135/refs.dat">CDS</a>. Individual notes on each HMXB are also available for <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/442/1135/notes1.dat">SMC systems</a> and for <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/442/1135/notes2.dat">LMC systems</a> at the same site. This Browse table contains the combination of 92 HMXBs in the SMC and 36 HMXBs in the LMC which were listed in Tables 1 and 2, respectively, of the published version of this catalog. The HEASARC has added a parameter called cloud_id which can be used to identify which Magellanic Cloud any specified HMXB belongs to (the SMC or the LMC). This database was created by the HEASARC in December 2005 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/442/1135">CDS Catalog J/A+A/442/1135</a>, table1.dat and table2.dat. This is a service provided by NASA HEASARC .
