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- ID:
- ivo://CDS.VizieR/J/ApJ/641/140
- Title:
- Optical counterparts in the NDWFS Bootes field
- Short Name:
- J/ApJ/641/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XBootes Survey is a 5ks Chandra survey of the Bootes Field of the NOAO Deep Wide-Field Survey (NDWFS). This survey is unique in that it is the largest (9.3{deg}^2^) contiguous region imaged in X-ray with complementary deep optical and near-infrared (near-IR) observations. We present a catalog of the optical counterparts to the 3213 X-ray point sources detected in the XBootes survey. Using a Bayesian identification scheme, we successfully identified optical counterparts for 98% of the X-ray point sources.
- ID:
- ivo://CDS.VizieR/J/ApJS/214/10
- Title:
- Optical counterparts of Chandra GBS sources
- Short Name:
- J/ApJS/214/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical light curves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey (GBS). Using data from the Mosaic-II instrument on the Blanco 4m Telescope at CTIO, we gathered time-resolved photometric data on timescales from ~2hr to 8 days over the 3/4 of the X-ray survey containing sources from the initial GBS catalog. Among the light curve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. Eighty-seven percent of X-ray sources have at least one potential optical counterpart. Twenty-seven percent of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and discuss the characteristics of the variable population.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A42
- Title:
- Optical counterparts of ROSAT X-ray in 2 fields
- Short Name:
- J/A+A/575/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The optical identification of large number of X-ray sources such as those from the ROSAT All-Sky Survey is challenging with conventional spectroscopic follow-up observations. We investigate two ROSAT All-Sky Survey fields of size 10{deg}x10{deg} each, one at galactic latitude b=83{deg} (26 Com), the other at b=-5{deg} (gamma Sge), in order to optically identify the majority of sources. We used optical variability, among other more standard methods, as a means of identifying a large number of ROSAT All- Sky Survey sources. All objects fainter than about 12mag and brighter than about 17mag, in or near the error circle of the ROSAT positions, were tested for optical variability on hundreds of archival plates of the Sonneberg field patrol.
- ID:
- ivo://CDS.VizieR/J/AcA/62/133
- Title:
- Optical counterparts of X-ray sources in OGLE
- Short Name:
- J/AcA/62/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 209 variable objects - very likely optical counterparts to the X-ray sources detected in the direction of the Galactic center by the Galactic Bulge Survey (GBS) carried out with the Chandra satellite. The variable sources were found in the databases of the OGLE long term survey monitoring regularly the Galactic bulge since 1992. The counterpart candidates were searched based on the X-ray source position in the radius of 3.9 arcsec.
- ID:
- ivo://CDS.VizieR/J/other/PABei/30.106
- Title:
- Optical identification of ROSAT AGN
- Short Name:
- J/other/PABei/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The completeness of sample is especially important for the research of quasar and using data in one wavelength, such as in radio, infrared, optical or X-ray selection, to make candidate selection always suffers significant selection effect to some extent. Fortunately, some large area surveys have become increasingly prevalent across all wavelengths over the past decade, such as SDSS, NVSS, FIRST, RASS, etc. These surveys make it possible to select candidates in multiple wavelengths and the resulting sample is more complete.
- ID:
- ivo://CDS.VizieR/J/A+A/449/425
- Title:
- Optical identification of ROSAT-FSC sources
- Short Name:
- J/A+A/449/425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Byurakan/Hamburg/ROSAT Catalogue (BHRC) of the optical identifications of X-ray sources is presented. The BHRC includes all 2791 sources from the ROSAT-FSC (<IX/29>) with |b|>30, DEC>0 and ROSAT count rate CR>0.04cts/s. The optical identifications were carried out by means of the Hamburg Quasar Survey (HQS) digitized spectroscopic plates, the DSS1 and DSS2 (blue, red, and IR) images, and other available data. We managed to identify 97% of sources (2696 sources) that are associated with 3202 optical objects. 2248 X-ray sources have a single optical counterpart, 144 have a double or multiple optical counterpart (binaries, galaxy groups etc.), and 304 have ambiguous identifications. The table gives all available multiwavelength data for the identified sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/401/294
- Title:
- Optical identification of XMM-LSS sources
- Short Name:
- J/MNRAS/401/294
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical spectroscopic identifications of X-ray sources in ~3deg^2^ of the XMM-Large Scale Structure survey (XMM-LSS), also covered by the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS), obtained with the AAOmega instrument at the Anglo-Australian Telescope. In a flux-limited sample of 829 point-like sources in the optical band with g'<=22mag and the 0.5-2keV flux (f_0.5-2keV_)>10^-15^erg/cm^2^/s, we observed 693 objects and obtained reliable spectroscopic identification for 487 sources, approximately 59 per cent of the overall sample.
- ID:
- ivo://CDS.VizieR/J/MNRAS/274/1194
- Title:
- Optical Identifications of ROSAT EUV Sources
- Short Name:
- J/MNRAS/274/1194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical identifications for 195 EUV sources located in the ROSAT Wide Field Camera all-Sky survey are presented. We list 69 previous unknown EUV-emitting white dwarfs, 114 active stars, 7 new magnetic cataclysmic variables and 5 active galaxies. Several of the white dwarfs have resolved M-type companions, while five are unresolved white dwarf/M-star pairs. Finding charts are given for the optical counterparts.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2579
- Title:
- Optical ident. of BATC Sky Survey X-ray sources
- Short Name:
- J/AJ/127/2579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical candidates for 75 X-ray sources in a 1deg^2^ overlapping region with the 1997 medium-deep ROSAT survey by Molthagen et al. (1996, Cat. <J/A+AS/126/509>). These candidates are selected using the multicolor CCD imaging observations made for the T329 field of the Beijing-Arizona-Taiwan-Connecticut (BATC) Sky Survey, which uses the NAOC 0.6/0.9m Schmidt telescope with 15 intermediate-band filters covering the wavelength range 3360-9745{AA}. These X-ray sources are relatively faint (CR<<0.2ct/s) and thus are mostly not included in the ROSAT Bright Source Catalogue; they also remain as X-ray sources without optical candidates in a previous identification program carried out by the Hamburg Quasar Survey (1998, <J/A+AS/128/507> and 1999, <J/A+AS/134/483>).
