Browsing by Subject "catalogs"

Now showing 1 - 8 of 8
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    A catalogue of galaxies behind the southern Milky Way: II. The Crux and Great Attractor regions ($lapprox$ 289° to 338°)
    (2001) Woudt, P A; Kraan-Korteweg, R C
    In this second paper of the catalogue series of galaxies behind the southern Milky Way, we report on the deep optical galaxy search in the Crux region (
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    Extragalactic large-scale structures behind the southern Milky Way: IV. Redshifts obtained with MEFOS
    (2004) Woudt, P A; Kraan-Korteweg, R C; Cayatte, V; Balkowski, C; Felenbok, P
    Abbreviated: As part of our efforts to unveil extragalactic large-scale structures behind the southern Milky Way, we here present redshifts for 764 galaxies in the Hydra/Antlia, Crux and Great Attractor region (266deg < l < 338deg, < 10deg), obtained with the Meudon-ESO Fibre Object Spectrograph (MEFOS) at the 3.6-m telescope of ESO. The observations are part of a redshift survey of partially obscured galaxies recorded in the course of a deep optical galaxy search behind the southern Milky Way. A total of 947 galaxies have been observed, a small percentage of the spectra (N=109, 11.5%) were contaminated by foreground stars, and 74 galaxies (7.8%) were too faint to allow a reliable redshift determination. With MEFOS we obtained spectra down to the faintest galaxies of our optical galaxy survey, and hence probe large-scale structures out to larger distances (v <~ 30000 km/s) than our other redshift follow-ups. The most distinct large-scale structures revealed in the southern Zone of Avoidance are discussed in context to known structures adjacent to the Milky Way.
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    Parkes H I observations of galaxies behind the southern Milky Way II. The Crux and Great Attractor regions (l ≈ 289◦ to 338◦)***
    (2009) Schröder, A C; Kraan-Korteweg, R C; Henning, P A
    As part of our programme to map the large-scale distribution of galaxies behind the southern Milky Way, we observed 314 optically-selected, partially-obscured galaxies in the Zone of Avoidance (ZOA) in the Crux and Great Attractor (GA) regions. An additional 29 galaxies were observed in the Vela ZOA survey region (because of the small numbers they are not discussed any further). The observations were conducted with the Parkes 64 m (210 ft) radio telescope, in a single-pixel pointed mode, reaching an rms noise level of typically $2{-}6$ mJy over the velocity search range of 400 < v < 10 500 km s-1. A total of 162 galaxies were detected (plus 14 galaxies in the Vela region). The detection rate is slightly higher than for the Hydra/Antlia region (52% versus 45%) observed in the same way. This can be explained by the prominence of the GA overdensity in the survey regions, which leads to a relatively higher fraction of nearby galaxies. It is also evident from the quite narrow velocity distribution (largely confined to $3000{-}6000$ km s-1) and deviates significantly from the expectation of a uniform galaxy distribution for the given sensitivity and velocity range. No systematic differences were found between detections and non-detections, in terms of latitude, foreground extinction, or environment, except for the very central part of the rich Norma cluster, where hardly any galaxies were detected. A detailed investigation of the H i content of the galaxies reveals strong H i deficiency at the core of the Norma cluster (within about a 0.4 Abell radius), similar to what has been found in the Coma cluster. The redshifts obtained by this observing technique result in a substantial reduction of the so-called redshift ZOA. This is obvious when analysing the large-scale structure of the new H i data in combination with data from other (optical) ZOA redshift surveys. The lower latitude detections provide further evidence of the extension of the Norma Wall, across the ZOA, in particular its bending towards the Cen-Crux clusters above the Galactic plane at slightly higher redshift, rather than a straight continuation towards the Centaurus clusters.
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    The GMRT 150 MHz all-sky radio survey: First alternative data release TGSS ADR1
    (2017) Intema, H T; Jagannathan, P; Mooley, K P; Frail, D A
    We present the first full release of a survey of the 150 MHz radio sky, observed with the Giant Metrewave Radio Telescope (GMRT) between April 2010 and March 2012 as part of the TIFR GMRT Sky Survey (TGSS) project. Aimed at producing a reliable compact source survey, our automated data reduction pipeline efficiently processed more than 2000 h of observations with minimal human interaction. Through application of innovative techniques such as image-based flagging, direction-dependent calibration of ionospheric phase errors, correcting for systematic offsets in antenna pointing, and improving the primary beam model, we created good quality images for over 95 percent of the 5336 pointings. Our data release covers 36 900 deg2 (or 3.6 π steradians) of the sky between −53° and +90° declination (Dec), which is 90 percent of the total sky. The majority of pointing images have a noise level below 5 mJy beam-1 with an approximate resolution of 25′′×25′′ (or 25′′×25′′/ cos(Dec−19°) for pointings south of 19° declination). We have produced a catalog of 0.62 Million radio sources derived from an initial, high reliability source extraction at the seven sigma level. For the bulk of the survey, the measured overall astrometric accuracy is better than two arcseconds in right ascension and declination, while the flux density accuracy is estimated at approximately ten percent. Within the scope of the TGSS alternative data release (TGSS ADR) project, the source catalog, as well as 5336 mosaic images (5°×5°) and an image cutout service, are made publicly available at the CDS as a service to the astronomical community. Next to enabling a wide range of different scientific investigations, we anticipate that these survey products will provide a solid reference for various new low-frequency radio aperture array telescopes (LOFAR, LWA, MWA, SKA-low), and can play an important role in characterizing the epoch-of-reionisation (EoR) foreground. The TGSS ADR project aims at continuously improving the quality of the survey data products. Near-future improvements include replacement of bright source snapshot images with archival targeted observations, using new observations to fill the holes in sky coverage and replace very poor quality observational data, and an improved flux calibration strategy for less severely affected observational data.
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    The LOFAR Two-metre Sky Survey: I. Survey description and preliminary data release⋆
    (2017) Shimwell, T W; Röttgering, H J A; Best, P N; Williams, W L; Dijkema, T J; de Gasperin, F; Hardcastle, M J; Heald, G H; Hoang, D N; Horneffer, A; Intema, H; Mahony, E K; Mandal, S; Mechev, A P; Morabito, L; Oonk, J B R; Rafferty, D; Retana-Montenegro, E; Sabater, J; Tasse, C; van Weeren, R J; BrYggen, M; Brunetti, G; Chyży, K T; Conway, J E; Haverkorn, M; Jackson, N; Jarvis, M J; McKean, J P; Miley, G K; Morganti, R; White, G J
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    The seventh data release of the sloan digital sky survey
    (2009) Abazajian, Kevork N; Adelman‐McCarthy, Jennifer K; AgYeros, Marcel A; Allam, Sahar S; Prieto, Carlos Allende; An, Deokkeun; Anderson, Kurt S J; Anderson, Scott F; Annis, James; Bahcall, Neta A; Bailer‐Jones, C A L; Barentine, J C; Bassett, Bruce A; Becker, Andrew C; Beers, Timothy C; Bell, Eric F; Belokurov, Vasily; Berlind, Andreas A; Berman, Eileen F; Bernardi, Mariangela; Bickerton, Steven J; Bizyaev, Dmitry; Blakeslee, John P; Blanton, Michael R; Bochanski, John J; Boroski, William N; Brewington, Howard J; Brinchmann, Jarle; Brinkmann, J; Brunner, Robert J; Budavári, Tamás; Carey, Larry N
    This paper describes the Seventh Data Release of the Sloan Digital Sky Survey (SDSS), marking the completion of the original goals of the SDSS and the end of the phase known as SDSS-II. It includes 11, 663 deg2 of imaging data, with most of the ~2000 deg2 increment over the previous data release lying in regions of low Galactic latitude. The catalog contains five-band photometry for 357 million distinct objects. The survey also includes repeat photometry on a 120° long, 2fdg5 wide stripe along the celestial equator in the Southern Galactic Cap, with some regions covered by as many as 90 individual imaging runs. We include a co-addition of the best of these data, going roughly 2 mag fainter than the main survey over 250 deg2. The survey has completed spectroscopy over 9380 deg2 the spectroscopy is now complete over a large contiguous area of the Northern Galactic Cap, closing the gap that was present in previous data releases. There are over 1.6 million spectra in total, including 930, 000 galaxies, 120, 000 quasars, and 460, 000 stars. The data release includes improved stellar photometry at low Galactic latitude. The astrometry has all been recalibrated with the second version of the USNO CCD Astrograph Catalog, reducing the rms statistical errors at the bright end to 45 milliarcseconds per coordinate. We further quantify a systematic error in bright galaxy photometry due to poor sky determination ; this problem is less severe than previously reported for the majority of galaxies. Finally, we describe a series of improvements to the spectroscopic reductions, including better flat fielding and improved wavelength calibration at the blue end, better processing of objects with extremely strong narrow emission lines, and an improved determination of stellar metallicities.
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    The sixth data release of the Sloan digital sky survey
    (2008) Adelman‐McCarthy, Jennifer K; AgYeros, Marcel A; Allam, Sahar S; Allende Prieto, Carlos; Anderson, Kurt S J; Anderson, Scott F; Annis, James; Bahcall, Neta A; Bailer‐Jones, C A L; Baldry, Ivan K; Barentine, J C; Bassett, Bruce A; Becker, Andrew C; Beers, Timothy C; Bell, Eric F; Berlind, Andreas A; Bernardi, Mariangela; Blanton, Michael R; Bochanski, John J; Boroski, William N; Brinchmann, Jarle; Brinkmann, J; Brunner, Robert J; Budavári, Tamás; Carliles, Samuel; Carr, Michael A; Castander, Francisco J; Cinabro, David; Cool, R J; Covey, Kevin R; Csabai, István; Cunha, Carlos E
    This paper describes the Sixth Data Release of the Sloan Digital Sky Survey. With this data release, the imaging of the northern Galactic cap is now complete. The survey contains images and parameters of roughly 287 million objects over 9583 deg2 , including scans over a large range of Galactic latitudes and longitudes. The survey also includes 1.27 million spectra of stars, galaxies, quasars, and blank sky (for sky subtraction) selected over 7425 deg2 . This release includes much more stellar spectroscopy than was available in previous data releases and also includes detailed estimates of stellar temperatures, gravities, and metallicities. The results of improved photometric calibration are now available, with uncertainties of roughly 1% in g, r, i, and z, and 2% in u, substantially better than the uncertainties in previous data releases. The spectra in this data release have improved wavelength and flux calibration, especially in the extreme blue and extreme red, leading to the qualitatively better determination of stellar types and radial velocities. The spectrophotometric fluxes are now tied to point-spread function magnitudes of stars rather than fiber magnitudes. This gives more robust results in the presence of seeing variations, but also implies a change in the spectrophotometric scale, which is now brighter by roughly 0.35 mag. Systematic errors in the velocity dispersions of galaxies have been fixed, and the results of two independent codes for determining spectral classifications and redshifts are made available. Additional spectral outputs are made available, including calibrated spectra from individual 15 minute exposures and the sky spectrum subtracted from each exposure. We also quantify a recently recognized underestimation of the brightnesses of galaxies of large angular extent due to poor sky subtraction; the bias can exceed 0.2 mag for galaxies brighter than r ¼ 14 mag.
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    Towards automatic classification of all WISE sources
    (2016) Kurcz, A; Bilicki, M; Solarz, A; Krupa, M; Pollo, A; Małek, K
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