- ID:
- ivo://CDS.VizieR/J/ApJS/217/2
- Title:
- Refined associations of Fermi/LAT sources
- Short Name:
- J/ApJS/217/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released in 2010 February and the Fermi-LAT 2-Year Source Catalog (2FGL) appeared in 2012 April, based on data from 24 months of operation. Since they were released, many follow up observations of unidentified {gamma}-ray sources have been performed and new procedures for associating {gamma}-ray sources with potential counterparts at other wavelengths have been developed. Here we review and characterize all of the associations as published in the 1FGL and 2FGL catalogs on the basis of multifrequency archival observations. In particular, we located 177 spectra for the low-energy counterparts that were not listed in the previous Fermi catalogs, and in addition we present new spectroscopic observations of eight {gamma}-ray blazar candidates. Based on our investigations, we introduce a new counterpart category of "candidate associations" and propose a refined classification for the candidate low-energy counterparts of the Fermi sources. We compare the 1FGL-assigned counterparts with those listed in 2FGL to determine which unassociated sources became associated in later releases of the Fermi catalogs. We also search for potential counterparts to all of the remaining unassociated Fermi sources. Finally, we prepare a refined and merged list of all of the associations of 1FGL plus 2FGL that includes 2219 unique Fermi objects. This is the most comprehensive and systematic study of all the associations collected for the {gamma}-ray sources available to date. We conclude that 80% of the Fermi sources have at least one known plausible {gamma}-ray emitter within their positional uncertainty regions.
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- ID:
- ivo://CDS.VizieR/J/A+A/652/A2
- Title:
- rho Oph region revisited with Gaia EDR3
- Short Name:
- J/A+A/652/A2
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Young and embedded stellar populations are important probes of the star formation process. Their properties and the environments they create have the potential to affect the formation of new planets. Paradoxically, we have a better census of nearby embedded young populations than of the slightly more evolved optically visible young populations. The high accuracy measurements and all-sky coverage of Gaia data are about to change this situation. This work aims to construct the most complete sample to date of YSOs in the {rho} Oph region. We compile a catalog of 1114 Ophiuchus YSOs from the literature and crossmatch it with the Gaia EDR3, Gaia-ESO, and APOGEE-2 surveys. We apply a multivariate classification algorithm to this catalog to identify new, co- moving population candidates. We find 191 high-fidelity new YSO candidates in the Gaia EDR3 catalog belonging to the {rho} Oph region. The new sources appear to be mainly Class III M-stars and substellar objects and are less extincted than the known members, while we find that 28 of previously unknown sources are YSOs with circumstellar disks (Class I or Class II). The analysis of the proper motion distribution of the entire sample reveals a well-defined bimodality, implying two distinct populations sharing a similar 3D volume. The first population comprises young stars' clusters around the {rho} Ophiuchi star and the main Ophiuchus clouds (L1688, L1689, L1709). In contrast, the second population is slightly older (~10Myr), more dispersed, has a distinct proper motion, and is possibly from the Upper-Sco group. The two populations are moving away from each other at about 4.1km/s and will no longer overlap in about 4Myr. Finally, we flag 17 sources in the literature sample as likely impostors, which are sources that exhibit large deviations from the average properties of the {rho} Oph population. Our results show the importance of accurate 3D space and motion information for improved stellar population analysis.
- ID:
- ivo://CDS.VizieR/J/A+A/378/30
- Title:
- ROSAT-BSC galaxy identifications
- Short Name:
- J/A+A/378/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In a correlation study of the ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, Cat. <XI/10>) with the Catalogue of Principal Galaxies (PGC, Cat. <VII/119>) 904 X-ray sources were found that possess possible extragalactic counterparts within a search radius of 100". File table1 contains 1124 optical galaxy entries and 904 relevant X-ray candidates/counterparts from the ROSAT All-Sky Survey. Besides a compilation of X-ray and optical parameters for each source, also the results of an identification screening are given. 547 optical/X-ray correlations have been quoted as reliable identifications. The 904 optical images with X-ray overlay contours (xID_nnn.ps.gz) used in the screening process are added for each user's own judgement.
- ID:
- ivo://CDS.VizieR/J/A+AS/132/341
- Title:
- ROSAT GPS optical identification
- Short Name:
- J/A+AS/132/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on optical searches in the error circles of 93 ROSAT survey sources located at low galactic latitudes (|b|<20{deg}). These sources were extracted from the ROSAT Galactic Plane Survey using various selection criteria on hardness ratio, X-ray and optical brightness and integrated galactic absorption in the direction of the source. We find optical identifications in 76 cases, among which are 25 new AGN, 6 new CVs and a new Be/X-ray binary. In order to illustrate the relevance of the source selections applied here, we cross-correlated the ROSAT all-sky survey bright source list with SIMBAD. Different classes of X-ray emitters populate distinct regions of a multi dimensional parameter space involving flux ratios, galactic latitude and N_H_. This relatively good segregation offers the possibility to build source samples with enhanced probability of identification with a given class. Complete optical identification of such subsamples could eventually be used to compute meaningful probabilities of identification for all sources using as basis a restricted set of multi-wavelength information.
- ID:
- ivo://CDS.VizieR/J/ApJS/149/29
- Title:
- ROSAT North Ecliptic Pole Survey
- Short Name:
- J/ApJS/149/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The X-ray data around the North Ecliptic Pole (NEP) of the ROSAT All Sky Survey have been used to construct a contiguous area survey consisting of a sample of 445 individual X-ray sources above a flux of ~2x10^-14^erg/cm^2^/s in the 0.5-2.0keV energy band. The NEP survey is centered at RA=18:00 (2000) DE=+66:33 and covers a region of 80.7deg^2^ at a moderate Galactic latitude of b=29.8{deg}. Hence, the NEP survey is as deep and covers a comparable solid angle to the ROSAT serendipitous surveys but is also contiguous. We have identified 99.6% of the sources and determined redshifts for the extragalactic objects. In this paper we present the optical identifications of the NEP catalog of X-ray sources including basic X-ray data and properties of the sources. We also describe with some detail the optical identification procedure. The classification of the optical counterparts to the NEP sources is very similar to that of previous surveys, in particular the Einstein Extended Medium Sensitivity Survey (EMSS). The main constituents of the catalog are active galactic nuclei (AGNs) (~49%), either type 1 or type 2 according to the broadness of their permitted emission lines. Stellar counterparts are the second most common identification class (~34%). Clusters and groups of galaxies comprise 14%, and BL Lacertae objects 2%. One non-AGN galaxy and one planetary nebula have also been found. The NEP catalog of X-ray sources is a homogeneous sample of astronomical objects featuring complete optical identification.
- ID:
- ivo://CDS.VizieR/J/ApJ/595/1206
- Title:
- ROSAT view of Hipparcos F stars
- Short Name:
- J/ApJ/595/1206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For a set of 11900 F stars that have uvby photometry and are in the Hipparcos (Cat. <I/239>) catalog, we have found 1980 X-ray counterparts (~17%) in the ROSAT All-Sky Surveys (RASS, Cat. <IX/10> and <IX/29>). In this paper we analyze X-ray properties of these ROSAT F stars and compare that sample with the entire set of our F stars.
- ID:
- ivo://CDS.VizieR/J/A+A/390/173
- Title:
- RR Lyrae GCVS and TYC2 identifiers
- Short Name:
- J/A+A/390/173
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Tycho-2 catalogue (<I/259>) provides astrometric and photometric data for the 2.5 million brightest stars in the sky. Therefore it can provide much larger samples than the Hipparcos samples used to date in statistical studies. The object of this paper is the cross-identification of Tycho-2 sources and known variable stars of RR Lyrae type. The Tycho-2 data of cross-identified sources are added into the ASTRID specialized database. The present selection almost doubles the size of the sample of RR Lyrae stars with available proper motions.
- ID:
- ivo://CDS.VizieR/J/A+A/402/801
- Title:
- Runaway carbon stars of Blanco & McCarthy field 37
- Short Name:
- J/A+A/402/801
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have been recently faced with the problem of cross-identifying stars recorded in historical catalogues with those extracted from recent fully digitized surveys (such as DENIS and 2MASS). Positions mentioned in the old catalogues are frequently of poor precision, but are generally accompanied by finding charts where the interesting objects are flagged. Those finding charts are sometimes our only link with the accumulated knowledge of past literature. While checking the identification of some of these objects in several catalogues, we had the surprise to discover a number of discrepancies in recent works.The main reason for these discrepancies was generally the blind application of the smallest difference in position as the criterion to identify sources from one historical catalogue to those in more recent surveys. In this paper we give examples of such mis-identifications, and show how we were able to find and correct them.We present modern procedures to discover and solve cross-identification problems, such as loading digitized images of the sky through the Aladin service at CDS, and overlaying entries from historical catalogues and modern surveys. We conclude that the use of good finding charts still remains the ultimate (though time-consuming) tool to ascertain cross-identifications in difficult cases.
299. SAGE AGB candidates
- ID:
- ivo://CDS.VizieR/J/ApJ/723/1195
- Title:
- SAGE AGB candidates
- Short Name:
- J/ApJ/723/1195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We combine variability information from the MAssive Compact Halo Objects survey of the Large Magellanic Cloud with infrared photometry from the Spitzer Space Telescope Surveying the Agents of a Galaxy's Evolution survey to create a data set of ~30000 variable red sources. We photometrically classify these sources as being on the first ascent of the red giant branch, or as being in one of three stages along the asymptotic giant branch (AGB): oxygen-rich, carbon-rich, or highly reddened with indeterminate chemistry ("extreme" AGB candidates). We present linear period-luminosity (P-L) relationships for these sources using eight separate infrared bands (J, H, Ks, 3.6, 4.5, 5.8, 8.0, and 24um) as proxies for the luminosity. We find that the wavelength dependence of the slope of the P-L relationship is different for different photometrically determined classes of AGB stars. Stars photometrically classified as O-rich show the least variation of slope with wavelength, while dust enshrouded extreme AGB stars show a pronounced trend toward steeper slopes with increasing wavelength. We find that O-rich AGB stars pulsating in the fundamental mode obey a period-magnitude relation with a slope of -3.41+/-0.04 when magnitude is measured in the 3.6um band, in contrast to C-rich AGB stars, which obey a relation of slope -3.77+/-0.05.
- ID:
- ivo://CDS.VizieR/I/222
- Title:
- San Fernando AC Zone Data Reduced to ACRS
- Short Name:
- I/222
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The U.S. Naval Observatory is in the process of making new reductions of the Astrographic Catalogue (AC) using a modern reference system, the ACRS, which represents the system of the FK5. The data from the San Fernando Zone, whose plates are centered between declinations -3 and -9 degrees (eq. 1900), have been analyzed for scale, rotation, tilt, coma, magnitude equation, radial distortion and distortions introduced by the use of reseaux in the Carte du Ciel program. The result is a positional catalog of over 225,000 stars on eq. J2000.0, epoch of observation. Additionally, all stars have been matched with the Tycho Input Catalog (revised); those numbers have been added for additional identification purposes.
