Search

Start Over Subject astrometry Validation Level 2
11. ACR catalog around Celestial Equator
ID:
ivo://CDS.VizieR/I/263
Title:
ACR catalog around Celestial Equator
Short Name:
I/263
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present improved and highly accurate International Celestial Reference System (ICRS) equatorial positions for 1,268,732 stars in 16 astrometric calibration regions located around the celestial equator. Each region is about 7.6{deg}x3.2{deg} in area (~24.3 deg^2^), contains a large number of stars (18,767 to 263,810), has stellar densities ranging from 765 to 10,772 stars deg^-2^, covers a wide range in magnitude (9.5<R<17.8, or equivalently 10.0<V<18.3), and is complete to magnitude R~17.2 (V~17.7). All of the observations were taken in 1994-1998 (mean epoch J1996.0) with the Flagstaff Astrometric Scanning Transit Telescope. Furthermore, each region was observed many times with overlapped CCD strip scans, and these data were reduced to star positions using differential reductions. The reference-star positions were taken from the ACT catalog of accurate star positions and proper motions. The star positions presented herein are typically accurate to +/-26mas (+/-12mas precision) in both right ascension and declination, except for the faintest stars, whose errors are about 2 times larger. Similarly, magnitudes were determined for the astrometric calibration stars using standard photometric reductions, and accuracies of +/-18mmag (+/-10mmag precisions) were achieved (about +/-46mmag for the faintest stars)
12. AGILE Mini-Calorimeter {gamma}-ray burst catalog
ID:
ivo://CDS.VizieR/J/A+A/553/A33
Title:
AGILE Mini-Calorimeter {gamma}-ray burst catalog
Short Name:
J/A+A/553/A33
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Mini-Calorimeter of the AGILE satellite can observe the high-energy part of gamma-ray bursts with good timing capability. We present the data of the 85 hard gamma-ray bursts observed by the Mini-Calorimeter since the launch (April 2007) until October 2009. We report the timing data for 84 and spectral data for 21 bursts.
13. AGK1 catalog, -2{deg} 10'=<DE<=+1{deg} 10'
ID:
ivo://CDS.VizieR/I/310
Title:
AGK1 catalog, -2{deg} 10'=<DE<=+1{deg} 10'
Short Name:
I/310
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue contains 5954 stars obtained in the course of observational campaign of the AGK1 programme that is the German abbreviation, which stands for the catalogue of astronomical society. The observations were carried out at Nikolaev Astronomical Observatory (Ukraine) in 1876-1899 with the Reichenbach meridian circle made in 1825. Magnitude range of stars is from 2.2 to 9.1 The declination zone is from -2{deg}10' to +1{deg}10'. Fourteen stars from the Fundamental Catalogue were included in the catalogue, namely: 0542, 1364, 1409, 3276, 3397, 3446, 3602, 3748, 5001, 5082, 5571, 5629, 5681, 5825. The probable errors of RA and Dec are 28ms and 490mas correspondingly.
14. AGK3 Catalogue
ID:
ivo://CDS.VizieR/I/61B
Title:
AGK3 Catalogue
Short Name:
I/61B
Date:
21 Oct 2021
Publisher:
CDS
Description:
The AGK3 provides positions and proper motions for stars north of -2.5 degrees. For the most part, it contains the stars in the AGK2 but is based on newly remeasured reference stars whose positions were reduced to the FK4 system. A list of 446 AGK2 stars not in the AGK3 and of three new stars is provided. All plates were taken at the Bergedorf Observatory. In addition to the positions and proper motions, the catalog contains magnitudes and spectral types, the epoch of the observations, the epoch difference between the AGK2 and AGK3, and the BD numbers.
15. AGK3R
ID:
ivo://CDS.VizieR/I/161
Title:
AGK3R
Short Name:
I/161
Date:
21 Oct 2021
Publisher:
CDS
Description:
A catalog of positions of reference stars distributed uniformly on the celestial sphere north of declination -5 deg. contains meridian observations of 21,499 stars with a mean epoch 1958.5. This catalog was compiled from more than 300,000 observations made with 11 northern meridian circles during the period 1956 to 1963. The observations are on the FK4 system.
16. AGK3R mean positions and proper motions
ID:
ivo://CDS.VizieR/I/72
Title:
AGK3R mean positions and proper motions
Short Name:
I/72
Date:
21 Oct 2021
Publisher:
CDS
Description:
The AGK3R and SRS are lists of reference stars containing, respectively, 21,499 stars in the northern hemisphere and 20,500 stars in the southern hemisphere. This paper presents computations of proper motions of these two groups of stars that will permit the use of the observed positions away from the epochs of observation. Tables are presented summarizing the mean errors of AGK3R proper motions and the observational histories of AGK3R and SRS stars.
17. AGK3U
ID:
ivo://CDS.VizieR/I/176
Title:
AGK3U
Short Name:
I/176
Date:
21 Oct 2021
Publisher:
CDS
Description:
The AGK3U is a updated version of the AGK3 catalog in which new positions from the Palomar "Quick V" survey have been added to improve the AGK3 proper motions. It provides FK4/B1950.0 positions and proper motions for 170,464 stars north of -2.5 degrees declination, at an average epoch of 1950.62. The proper motions have a two dimensional formal mean error of 0.82 arcsec/century. In addition to the positions and proper motions, the catalog contains the AGK3 number, the mean errors of the positions and proper motion in each coordinate, the photographic magnitude, the spectral type, and the Palomar plate position, epoch, and mean error.
18. AGN catalog from the AKARI NEP Wide field
ID:
ivo://CDS.VizieR/J/A+A/651/A108
Title:
AGN catalog from the AKARI NEP Wide field
Short Name:
J/A+A/651/A108
Date:
22 Feb 2022
Publisher:
CDS
Description:
The North Ecliptic Pole (NEP) field provides a unique set of panchromatic data, well suited for active galactic nuclei (AGN) studies. Selection of AGN candidates is often based on mid-infrared (MIR) measurements. Such method, despite its effectiveness, strongly reduces a catalog volume due to the MIR detection condition. Modern machine learning techniques can solve this problem by finding similar selection criteria using only optical and near-infrared (NIR) data. Aims of this work were to create a reliable AGN candidates catalog from the NEP field using a combination of optical SUBARU/HSC and NIR AKARI/IRC data and, consequently, to develop an efficient alternative for the MIR-based AKARI/IRC selection technique. A set of supervised machine learning algorithms was tested in order to perform an efficient AGN selection. Best of the models were formed into a majority voting scheme, which used the most popular classification result to produce the final AGN catalog. Additional analysis of catalog properties was performed in form of the spectral energy distribution (SED) fitting via the CIGALE software. The obtained catalog of 465 AGN candidates (out of 33119 objects) is characterized by 73% purity and 64% completeness. This new classification shows consistency with the MIR-based selection. Moreover, 76% of the obtained catalog can be found only with the new method due to the lack of MIR detection for most of the new AGN candidates. Training data, codes and final catalog are available via the github repository. Final AGN candidates catalog is also available via the CDS service.
19. AGN data and absorption-line measurements
ID:
ivo://CDS.VizieR/J/A+A/590/A68
Title:
AGN data and absorption-line measurements
Short Name:
J/A+A/590/A68
Date:
21 Oct 2021
Publisher:
CDS
Description:
Doubly ionized silicon (SiIII) is a powerful tracer of diffuse ionized gas inside and outside of galaxies.It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening SiIII-selected absorbers and study the properties of the warm circumgalactic medium (CGM) around low-redshift (z<0.1) galaxies. We analyzed the UV absorption spectra of 303 extragalactic background sources, as obtained with the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). We developed a geometrical model for the absorption-cross section of the CGM around the local galaxy population and compared the observed SiIII absorption statistics with predictions provided by the model. We also compared redshifts and positions of the absorbers with those of ~64,000 galaxies using archival galaxy-survey data to investigate the relation between intervening SiIII absorbers and the CGM. Along a total redshift path of {Delta}z~24, we identify 69 intervening SiIII systems that all show associated absorption from other low and high ions (e.g., HI, SiII, SiIV, CII, CIV). We derive a bias-corrected number density of dN/dz(SiIII)=2.5+/-0.4 for absorbers with column densities log N(SiIII)>12.2, which is ~3 times the number density of strong MgII systems at z=0. This number density matches the expected cross section of a SiIII absorbing CGM around the local galaxy population with a mean covering fraction of <f_c_>=0.69. For the majority (~60 percent) of the absorbers, we identify possible host galaxies within 300km/s of the absorbers and derive impact parameters {rho}<200kpc, demonstrating that the spatial distributions of SiIII absorbers and galaxies are highly correlated. Our study indicates that the majority of SiIII-selected absorbers in our sample trace the CGM of nearby galaxies within their virial radii at a typical covering fraction of ~70 percent. We estimate that diffuse gas in the CGM around galaxies, as traced by SiIII contains substantially more (more than twice as much) baryonic mass than their neutral interstellar medium.
20. AGN data and absorption-line measurements
ID:
ivo://CDS.VizieR/J/A+A/607/A48
Title:
AGN data and absorption-line measurements
Short Name:
J/A+A/607/A48
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Milky Way is surrounded by large amounts of diffuse gaseous matter that connects the stellar body of our Galaxy with its large-scale Local Group (LG) environment. To characterize the absorption properties of this circumgalactic medium (CGM) and its relation to the LG we present the so-far largest survey of metal absorption in Galactic high-velocity clouds (HVCs) using archival ultraviolet (UV) spectra of extragalactic background sources. The UV data are obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope (HST) and are supplemented by 21cm radio observations of neutral hydrogen. Along 270 sightlines we measure metal absorption in the lines of SiII, SiIII, CII, and CIV and associated HI 21cm emission in HVCs in the velocity range |v_LSR_|=100-500km/s. With this unprecedented large HVC sample we were able to improve the statistics on HVC covering fractions, ionization conditions, small-scale structure, CGM mass, and inflow rate. For the first time, we determine robustly the angular two point correlation function of the high-velocity absorbers, systematically analyze antipodal sightlines on the celestial sphere, and compare the HVC absorption characteristics with that of Damped Lyman alpha absorbers (DLAs) and constrained cosmological simulations of the LG (CLUES project). The overall sky-covering fraction of high-velocity absorption is 77+/-6 percent for the most sensitive ion in our survey, SiIII, and for column densities log N(SiIII)>12.1. This value is 4-5 times higher than the covering fraction of 21 cm neutral hydrogen emission at log N(HI)>18.7 along the same lines of sight, demonstrating that the Milky Way's CGM is multi-phase and predominantly ionized. The measured equivalent-width ratios of SiII, SiIII, CII, and CIV are inhomogeneously distributed on large and small angular scales, suggesting a complex spatial distribution of multi-phase gas that surrounds the neutral 21cm HVCs. We estimate that the total mass and accretion rate of the neutral and ionized CGM traced by HVCs is M_HVC_>3.0x10^9^M_{sun}_ and dM_HVC_/dt>6.1M_{sun}_/yr, where the Magellanic Stream (MS) contributes with more than 90 percent to this mass/mass-flow. If seen from an external vantage point, the Milky Way disk plus CGM would appear as a DLA that would exhibit for most viewing angles an extraordinary large velocity spread of dv=400-800km/s, a result of the complex kinematics of the Milky Way CGM that is dominated by the presence of the MS. We detect a velocity dipole of high-velocity absorption at low/high galactic latitudes that we associate with LG gas that streams to the LG barycenter. This scenario is supported by the gas kinematics predicted from the LG simulations. Our study confirms previous results, indicating that the Milky Way CGM contains sufficient gaseous material to feed the Milky Way disk over the next Gyr at a rate of a few solar masses per year, if the CGM gas can actually reach the MW disk. We demonstrate that the CGM is composed of discrete gaseous structures that exhibit a large-scale kinematics together with small-scale variations in physical conditions. The MS clearly dominates both the cross section and mass flow of high-velocity gas in the Milky Way's CGM. The possible presence of high-velocity LG gas underlines the important role of the local cosmological environment in the large-scale gas-circulation processes in and around the Milky Way.

Limit your search

more »

more »