We present in catalog form the optical identifications for objects from the first phase of the Wide Angle ROSAT Pointed Survey (WARPS). WARPS is a serendipitous survey of relatively deep, pointed ROSAT observations for clusters of galaxies. The X-ray source detection algorithm used by WARPS is Voronoi Tessellation and Percolation (VTP), a technique which is equally sensitive to point sources and extended sources of low surface brightness. WARPS-I is based on the central regions of 86 ROSAT PSPC fields, covering an area of 16.2 square degrees. We describe here the X-ray source screening and optical identification process for WARPS-I, which yielded 34 clusters at 0.06<z<0.75. Twenty-two of these clusters form a complete, statistically well-defined sample drawn from 75 of these 86 fields, covering an area of 14.1 square degrees, with a flux limit of F(0.5x2.0keV)=6.5x10^-14^erg/cm^2^/s. This sample can be used to study the properties and evolution of the gas, galaxy and dark matter content of clusters and to constrain cosmological parameters. We compare in detail the identification process and findings of WARPS to those from other recently published X-ray surveys for clusters, including RDCS, SHARC-Bright, SHARC-south, and the CfA 160deg^2^ survey.
This catalogue contains the two parts: the 9989 first stars are the standard and intermediary stars, +90 to -36 degrees of declination, observed in the years 1913 to 1926, and reduced without proper motion to the equinox 1920.0 ; the second part (stars numbered 9990 to 10571) are 582 miscellaneous stars.
The Washington Double Star Catalog (WDS), maintained by the United States Naval Observatory (USNO), is the world's principal database of astrometric double and multiple star information. The WDS Catalog contains positions, discoverer designations, epochs, position angles, separations, magnitudes, spectral types, proper motions and when available, Durchmusterung numbers and notes for the components of close to 100,000 systems based on ~600,000 means. The current version at the HEASARC is updated weekly and is derived from the version available online at <a href="https://crf.usno.navy.mil/wds/">https://crf.usno.navy.mil/wds/</a> (and mirrored at <a href="http://www.astro.gsu.edu/wds/">http://www.astro.gsu.edu/wds/</a>), the latter being potentially updated nightly. The Washington Visual Double Star Catalog (WDS) is the successor to the Index Catalogue of Visual Double Stars, 1961.0 (IDS; Jeffers & van den Bos, 1963). Three earlier double star catalogs in the 20th century, those by Burnham (BDS; 1906), Innes (SDS; 1927), and Aitken (ADS; 1932), each covered only a portion of the sky. Both the IDS and the WDS cover the entire sky, and the WDS is intended to contain all known visual double stars for which at least one differential measure has been published. The WDS is continually updated as published data become available. Prior to this, two major updates have been published (Worley & Douglass 1984, 1997). The Washington Double Star Catalog (WDS) has seen numerous changes since the last major release of the catalog. The application of many techniques and considerable industry over the past few years has yielded unprecedented gains in both the number of systems and the number of measures. This version of the WDS catalog was first created at the HEASARC in March 2002 based on the USNO online version (available at either <a href="https://crf.usno.navy.mil/wds/">https://crf.usno.navy.mil/wds/</a> or <a href="http://www.astro.gsu.edu/wds/">http://www.astro.gsu.edu/wds/</a>), and is updated by the HEASARC on at least a weekly basis. The table schema was last revised in February 2005. This is a service provided by NASA HEASARC .
To investigate the global properties of the globular cluster system (GCS) around NGC 5128, the central giant elliptical galaxy in the nearby Centaurus group, we have obtained deep CCD imaging for an area of almost 2{deg}^2^ centered on the galaxy. Our data, in the CMT_1_ Washington photometric system, reach an approximate limiting magnitude of T_1_~R~22 and contain magnitudes, colors, and coordinates for more than 100,000 objects. Of these, the vast majority (about 99%) are either foreground stars or faint background galaxies; the old-halo globular clusters make up the remaining tiny fraction of the sample. Our database, however, provides the material for understanding the large-scale features of the GCS, including its metallicity distribution (MDF), luminosity distribution, and spatial structure.
Building on the CMT_1_ photometric database presented in Paper I (Cat. <J/AJ/128/712>), in this paper we derive the large-scale properties of the globular cluster system (GCS) in NGC 5128, the nearest giant elliptical and the dominant galaxy in the Centaurus group. Using the metallicity-sensitive C-T_1_ color index, we discuss the metallicity distribution function (MDF) for a subsample of 211 previously identified clusters, all on a homogeneous photometric system. We find the MDF to be strongly bimodal, with metallicity peaks at [Fe/H]=-1.55 and -0.55 and with nearly equal numbers of clusters in each of the metal-poor and metal-rich modes. Finally, we present a list of 327 new cluster candidates not identified in any previous surveys; most of these are in the less well studied bulge region of the galaxy and along the minor axis.
We present Washington CT_1_T_2_ photometry of a field central to the Bootes I dwarf spheroidal galaxy, which was discovered as a stellar overdensity in the Sloan Digital Sky Survey (DR5). We show that the Washington filters are much more effective than the Sloan filters in separating the metal-poor turn-off stars in the dwarf galaxy from the foreground stars. We detect 165 objects in the field, and statistically determine that just over 40% of the objects are nonmembers. Our statistical analysis mostly agrees with radial velocity measurements of the brighter stars. We find that there is a distinct main-sequence turn-off and subgiant branch, where there is some evidence of a spread in chemical abundance.
Theoretical calculations and some indirect observations show that massive exoplanets on tight orbits must decay due to tidal dissipation within their host stars. This orbital evolution could be observationally accessible through precise transit timing over a course of decades. The rate of planetary in-spiraling may not only help us to understand some aspects of evolution of planetary systems, but also can be used as a probe of the stellar internal structure. In this paper we present results of transit timing campaigns organized for a carefully selected sample of the Northern hemisphere hot Jupiter-like planets which were found to be the best candidates for detecting planet-star tidal interactions. Among them, there is the WASP-12 system which is the best candidate for possessing an in-falling giant exoplanet. Our new observations support the scenario of orbital decay of WASP-12 b and allow us to refine its rate. The derived tidal quality parameter of the host star Q'*=(1.82+/-0.32)x10^5^ is in agreement with theoretical predictions for subgiant stars. For the remaining systems - HAT-P-23, KELT-1, KELT-16, WASP-33, and WASP-103 - our transit timing data reveal no deviations from the constant-period models, hence constraints on the individual rates of orbital decay were placed. The tidal quality parameters of host stars in at least four systems - HAT-P-23, KELT-1, WASP-33, and WASP-103 - were found to be greater than the value reported for WASP-12. This is in line with the finding that those hosts are main sequence stars, for which efficiency of tidal dissipation is predicted to be relatively weak.
We present 22 new transit observations of the exoplanets WASP-18Ab, WASP-19b, and WASP-77Ab, from the Transit Monitoring in the South (TraMoS) project. We simultaneously model our newly collected transit light curves with archival photometry and radial velocity data to obtain refined physical and orbital parameters. We include TESS light curves of the three exoplanets to perform an extended analysis of the variations in their transit mid-time (TTV) and to refine their planetary orbital ephemeris. We did not find significant TTVRMS variations larger than 47, 65, and 86 seconds for WASP-18Ab, WASP-19b, and WASP-77Ab, respectively. Dynamical simulations were carried out to constrain the masses of a possible perturber. The observed mean square (RMS) could be produced by a perturber body with an upper limit mass of 9, 2.5, 11 and 4M_{Earth}_ in 1:2, 1:3, 2:1, and 3:1 resonances in the WASP-18Ab system. In the case of WASP-19b, companions with masses up to 0.26, 0.65, 1, and 2.8M_{Earth}_, in 1:2, 2:1, 3:1, and 5:3 resonances respectively, produce the RMS. For the WASP-77Ab system, this RMS could be produced by a planet with mass in the range of 1.5-9M_{Earth}_ in 1:2, 1:3, 2:1, 2:3, 3:1, 3:5, or 5:3 resonances. Comparing our results with RV variations, we discard massive companions with 350M_{Earth}_ in 17:5 resonance for WASP-18Ab, 95M_{Earth}_ in 4:1 resonance for WASP-19b, and 105M_{Earth}_ in 5:2 resonance for WASP-77Ab. Finally, using a Lomb-Scargle period search we find no evidence of a periodic trend on our TTV data for the three exoplanets.
The TESS and PLATO missions are expected to find vast numbers of new transiting planet candidates. However, only a fraction of these candidates will be legitimate planets, and the candidate validation will require a significant amount of follow-up resources. Radial velocity (RV) follow-up study can be carried out only for the most promising candidates around bright, slowly rotating, stars. Thus, before devoting RV resources to candidates, they need to be vetted using cheaper methods, and, in the cases for which an RV confirmation is not feasible, the candidate's true nature needs to be determined based on these alternative methods alone. We study the applicability of multicolour transit photometry in the validation of transiting planet candidates when the candidate signal arises from a real astrophysical source (transiting planet, eclipsing binary, etc.), and not from an instrumental artefact. Particularly, we aim to answer how securely we can estimate the true uncontaminated star-planet radius ratio when the light curve may contain contamination from unresolved light sources inside the photometry aperture when combining multicolour transit observations with a physics-based contamination model in a Bayesian parameter estimation setting. More generally, we study how the contamination level, colour differences between the planet host and contaminant stars, transit signal-to-noise ratio, and available prior information affect the contamination and true radius ratio estimates. The study is based on simulations and ground-based multicolour transit observations. The contamination analyses were carried out with a contamination model integrated into the PYTRANSIT V2 transit modelling package, and the observations were carried out with the MuSCAT2 multicolour imager installed in the 1.5m Telescopio Carlos Sanchez in the Teide Observatory, in Tenerife. We show that multicolour transit photometry can be used to estimate the amount of flux contamination and the true radius ratio. Combining the true radius ratio with an estimate for the stellar radius yields the true absolute radius of the transiting object, which is a valuable quantity in statistical candidate validation, and enough in itself to validate a candidate whose radius falls below the theoretical lower limit for a brown dwarf.
We present the discovery by the WASP-South transit survey of three new transiting hot Jupiters, WASP-161 b, WASP-163 b and WASP-170 b. Follow-up radial velocities obtained with the Euler/CORALIE spectrograph and high-precision transit light curves obtained with the TRAPPIST-North, TRAPPIST-South, SPECULOOS-South, NITES, and Euler telescopes have enabled us to determine the masses and radii for these transiting exoplanets. WASP-161 b completes an orbit around its V=11.1 F6V-type host star in 5.406 days, and has a mass and radius of 2.5+/-0.2M_Jup_ and 1.14+/-0.06R_Jup_ respectively. WASP-163 b has an orbital period of 1.609-days, a mass of 1.9+/-0.2M_Jup_, and a radius of 1.2+/-0.1R_Jup_. Its host star is a V=12.5 G8-type dwarf. WASP-170 b is on a 2.344-days orbit around a G1V-type star of magnitude V=12.8. It has a mass of 1.7+/-0.2M_Jup_ and a radius of 1.14+/-0.09R_Jup_. Given their irradiations (~10^9^erg/s/cm^2^) and masses, the three new planets' sizes are in good agreement with classical structure models of irradiated giant planets.
![To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to the catalogue of astrometric microlensing events. For details, see the `Creative Commons CC0 1.0 Public Domain dedication <http://creativecommons.org/publicdomain/zero/1.0/>`_. Of course, you should still give proper credit when using this data as required by good scientific practice. .. image:: /static/img/cc0.png :alt: [CC0]](/registry-search/?f%5BcapabilityType_facet%5D%5B%5D=Simple+Cone+Search&f%5Brights_facet%5D%5B%5D=To+the+extent+possible+under+law%2C+the+publisher+has+waived+all+copyright+and+related+or+neighboring+rights+to+the+catalogue+of+astrometric+++microlensing+events.++For+details%2C+see+the+%60Creative+Commons+CC0+1.0+Public+Domain+dedication+%3Chttp%3A%2F%2Fcreativecommons.org%2Fpublicdomain%2Fzero%2F1.0%2F%3E%60_.++Of+course%2C+you+should+still+give+proper+credit+when+using+this+data+as+required+by+good+scientific+practice.%0A%0A..+image%3A%3A+%2Fstatic%2Fimg%2Fcc0.png%0A+++%3Aalt%3A+%5BCC0%5D%0A%0A){kind=link}