- ID:
- ivo://CDS.VizieR/J/MNRAS/321/77
- Title:
- Large-amplitude variables near the Galactic Centre
- Short Name:
- J/MNRAS/321/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report here the results of a 4-yr K-band (2.2mm) survey for large-amplitude variable stars in a 24x24arcmin^2^ area centred on the Galactic Centre. A total of 409 likely long-period variables (LPVs) were detected, for which positions, amplitudes, average magnitudes and periods were obtained whenever possible. The surface density of LPVs is more than ten times greater than in the Sgr I Baade window at l=-1.37{deg}, b=-2.63{deg}
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- ID:
- ivo://CDS.VizieR/J/MNRAS/424/2876
- Title:
- Large area KX quasar catalogue
- Short Name:
- J/MNRAS/424/2876
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a large area, ~600deg^2^, K-band flux-limited spectroscopic survey for luminous quasars are presented. The survey utilizes the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) in regions of sky within the Sloan Digital Sky Survey (SDSS) footprint. The K-band excess (KX) of all quasars with respect to Galactic stars is exploited in combination with a photometric redshift/classification scheme to identify quasar candidates for spectroscopic follow-up observations. The data contained within this investigation will be able to provide new constraints on the fraction of luminous quasars reddened by dust with E(B-V)<=0.5mag. The spectroscopic sample is defined using the K-band, 14.0<=K<=16.6, and SDSS i-band limits of i=19.5, 19.7 and 22.0 over sky areas of 287, 150 and 196deg^2^, respectively. The survey includes >3200 known quasars from the SDSS and more than 250 additional confirmed quasars from the KX selection. A well-defined subsample of quasars in the redshift interval 1.0<=z<=3.5 includes 1152 objects from the SDSS and 172 additional KX-selected quasars. The quasar selection is >95 per cent complete with respect to known SDSS quasars and >95 per cent efficient, largely independent of redshift and i-band magnitude. The properties of the new KX-selected quasars confirm the known redshift-dependent effectiveness of the SDSS quasar selection and provide a sample of luminous quasars experiencing intermediate levels of extinction by dust. The catalogue represents an important step towards the assembly of a well-defined sample of luminous quasars that may be used to investigate the properties of quasars experiencing intermediate levels of dust extinction within their host galaxies or due intervening absorption line systems.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A99
- Title:
- Large Quasar Astrometric Catalogue 2 (LQAC-2)
- Short Name:
- J/A+A/537/A99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- First of all we make a substantial review of the definitions and properties of quasars and AGN (Active Galactic Nuclei), the differenciation of these objects being unclear in the literature and even for specialists. This will serve our purpose when deciding which kinds of objects will be taken into account in our compilation. Then we carry out the cross-identification between the 9 catalogues of quasars chosen for their accuracy and their huge number of objects, using a flag for each of them, and including all the available data related to magnitudes (infrared and optical), radiofluxes and redshifts. We also perform cross identification with external catalogues 2MASS, B1.0 and GSC2.3 in order to complete photometric data of the objects. Moreover we compute the absolute magnitude of our extragalactic objects by taking into account the recent studies concerning the galactic absorption. In addition substantial improvements are brought with respect to the first release of the LQAC (Souchay et al., 2009, Cat. J/A+A/494/799). At first a LQAC name is given for each object based on its equatorial coordinates with respect to the ICRS, following a procedure which creates no ambiguity for identification. At second the equatorial coordinates of the objects are recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF) (Andrei et al., 2009, Cat. I/313). At third we introduce a morphological classification for the objects which enables in particular to define clearly if the object is point-like or extended. Our final catalogue, called LQAC-2, contains 187 504 quasars. This is roughly larger than the 113 666 quasars recorded in the first version of the LQAC (Souchay et al., 2009, Cat. J/A+A/494/799) and a little more than the number of quasars recorded in the up-dated version of the Veron Cetty and Veron (2010, Cat. VII/258) catalogue, which was the densest compilation of quasars up to now. In addition to the quantitative and qualitative improvements brought by our compilation, we discuss the homogeneity of the data and carry out statistical analysis concerning the spatial density and the distance to the closest neighbour.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A140
- Title:
- Large Quasar Astrometric Catalogue 4, LQAC-4
- Short Name:
- J/A+A/614/A140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From an astrometric point of view, quasars constitute the best and almost ideal reference objects in the celestial sphere, with a priori no significant proper motion. Since the third release of the Large Quasar Astrometric Catalogue (LQAC-3, Cat. J/A+A/583/A75), a large number of quasars have been discovered, in particular those coming from the DR12Q release of the SDSS (Paris et al., 2017, Cat. VII/279). Moreover, for cross-matched objects, we have taken advantage of the very accurate determinations of the quasars identified within the recent Gaia DR1 catalogue (2018, Cat. I/345). Following the same procedure as in the three previous releases of the LQAC, our aim is to compile the large majority of all the quasars recorded so far. Our goal is to record their best coordinates and substantial information concerning their physical properties such as the redshift as well as multi-bands apparent and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR1 catalogue. New quasars coming from the DR12Q release were cross-matched with the precedent LQAC-3 compilation with a 1" search radius, in order to add the objects without counterpart to the LQAC-4 compilation. A similar cross-match was done with Gaia DR1 to identify the known quasars detected by Gaia. This enables one to improve significantly the positioning of these objects, and in parallel to study the astrometric performance of the individual catalogues of the LQAC-4 compilation. Finally, a new method was used to determine absolute magnitudes. Our final catalogue, called LQAC-4, contains 443 725 objects. This is roughly 37.82% more than the number of objects recorded in the LQAC-3. Among them, 249071 were found in common with the Gaia DR1, with a 1" search radius. That corresponds to 56.13% of the whole population in the compilation. The LQAC-4 delivers to the astronomical community a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of compact AGNs), with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates come from the very recent Gaia DR1.
- ID:
- ivo://CDS.VizieR/J/A+A/583/A75
- Title:
- Large Quasar Astrometric Catalogue 3 (LQAC-3)
- Short Name:
- J/A+A/583/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with an a priori absence of proper motion. Since the second release of the Large Quasar Astrometric Catalog (LQAC), a large number of quasars have been discovered, in particular with the upcoming new release of the SDSS quasars catalog. Following the same procedure as in the two previous releases of the LQAC, our aim was to compile all the quasars recorded until the present date, with accurate recomputation of their equatorial coordinates in the ICRS and with the maximum of information concerning their physical properties, such as the redshift, the photometry, and the absolute magnitudes.
- ID:
- ivo://CDS.VizieR/J/A+A/494/799
- Title:
- Large Quasar Astrometric Catalogue (LQAC)
- Short Name:
- J/A+A/494/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The very large and increasing number of quasars reckoned from various sky surveys leads to a large quantity of data which brings various and inhomogeneous information in the fields of astrometry, photometry, radioastronomy and spectroscopy. In this paper, we describe our work that aims to make available a general compilation of the largest number of recorded quasars obtained from all the available catalogues, with their best position estimates, and providing physical information at both optical and radio wavelengths.
- ID:
- ivo://CDS.VizieR/J/ApJ/868/55
- Title:
- Large-scale structure of M31 halo. II. PAndAS
- Short Name:
- J/ApJ/868/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Pan-Andromeda Archaeological Survey is a survey of >400deg^2^ centered on the Andromeda (M31) and Triangulum (M33) galaxies that has provided the most extensive panorama of an L* galaxy group to large projected galactocentric radii. Here, we collate and summarize the current status of our knowledge of the substructures in the stellar halo of M31, and discuss connections between these features. We estimate that the 13 most distinctive substructures were produced by at least 5 different accretion events, all in the last 3 or 4Gyr. We suggest that a few of the substructures farthest from M31 may be shells from a single accretion event. We calculate the luminosities of some prominent substructures for which previous estimates were not available, and we estimate the stellar mass budget of the outer halo of M31. We revisit the problem of quantifying the properties of a highly structured data set; specifically, we use the OPTICS clustering algorithm to quantify the hierarchical structure of M31's stellar halo and identify three new faint structures. M31's halo, in projection, appears to be dominated by two "mega-structures", which can be considered as the two most significant branches of a merger tree produced by breaking M31's stellar halo into increasingly smaller structures based on the stellar spatial clustering. We conclude that OPTICS is a powerful algorithm that could be used in any astronomical application involving the hierarchical clustering of points.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/120
- Title:
- Large spectrosc. survey of Palomar 5 stellar stream
- Short Name:
- J/ApJ/842/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two spectroscopic surveys of the tidal stellar stream of the Palomar 5 globular cluster undertaken with the VLT/FLAMES and AAT/AAOmega instruments. We use these data in conjunction with photometric data presented in the previous contribution in this series to classify the survey stars in terms of their probability of belonging to the Palomar 5 stellar stream. We find that high-probability candidates are only found in a very narrow spatial interval surrounding the locus of the stream on the sky. PanSTARRS RRLyrae stars in this region of the sky are also distributed in a similar manner. The absence of significant "fanning" of this stellar stream confirms that Palomar 5 does not follow a chaotic orbit. Previous studies have found that Palomar 5 is largely devoid of low-mass stars, and we show that this is true also of the stellar populations along the trailing arm out to 6{deg}. Within this region, which contains 73% of the detected stars, the population is statistically identical to the core, implying that the ejection of the low-mass stars occurred before the formation of the stream. We also present an updated structural model fit to the bound remnant, which yields a total mass of 4297+/-98M_{sun}_ and a tidal radius 0.145+/-0.009kpc. We estimate the mass of the observed system including the stream to be 12200+/-400M_{sun}_, and the initial mass to have been ~47000+/-1500M_{sun}_.
- ID:
- ivo://CDS.VizieR/VII/228
- Title:
- Las Campanas Infrared Survey
- Short Name:
- VII/228
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Las Campanas Infrared Survey, based on broadband optical and near-infrared photometry, is designed to robustly identify a statistically significant and representative sample of evolved galaxies at redshifts z>1. We have completed an H-band imaging survey over 1.1{deg}^2^ of sky in six separate fields. The average 5{sigma} detection limit in a 4" diameter aperture is H~20.8. Here we describe the design of the survey, the observation strategies, data-reduction techniques, and object identification procedures. We present sample near-infrared and optical photometric catalogs for objects identified in two survey fields. The optical images of the Hubble Deep Field-South region obtained from the literature reach 5{sigma} detection thresholds in a 4" diameter aperture of U~24.6, B~26.1, V~25.6, R~25.1, and I~24.2mag. The optical images of the Chandra Deep Field-South region obtained from our own observations reach 5 {sigma} detection thresholds in a 4" diameter aperture of V~26.8, R~26.2, I~25.3, and z'~23.7mag. We perform object detection in all bandpasses and identify>~54000 galaxies over 1408 arcmin^2^ of sky in the two fields. Of these galaxies, ~14000 are detected in the H band and ~2000 have the colors of evolved galaxies, I-H >~3, at z>~1.
- ID:
- ivo://CDS.VizieR/J/MNRAS/361/525
- Title:
- Las Campanas Infrared Survey. V.
- Short Name:
- J/MNRAS/361/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep Keck spectroscopy, using the Deep Imaging Multi-Object Spectrograph and the Low-Resolution Imaging Spectrometer spectrographs, of a large and representative sample of 67 extremely red objects (EROs) to H=20.5 in three fields (SSA22, Chandra Deep Field South and NTT Deep Field) drawn from the Las Campanas Infrared Survey (LCIRS). Using the colour cut (I-H)>3.0 (Vega magnitudes) adopted in earlier papers in this series, we verify the efficiency of this selection for locating and studying distant old sources. Spectroscopic redshifts are determined for 44 sources, of which only two are contaminating low-mass stars. When allowance is made for incompleteness, the spectroscopic redshift distribution closely matches that predicted earlier on the basis of photometric data.
