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L Dwarfs Found in Sloan Digital Sky Survey Commissioning Data II. Hobby-Eberly Telescope Observations  [PDF]
Donald P. Schneider,Gillian R. Knapp,Suzanne L. Hawley,Kevin R. Covey,Xiaohui Fan,Lawrence W. Ramsey,Gordon T. Richards,Michael A. Strauss,James E. Gunn,Gary J. Hill,Phillip J. MacQueen,Mark T. Adams,Grant M. Hill,Zeljko Ivezic,Robert H. Lupton,Jeffrey R. Pier,David H. Saxe,Matthew Shetrone,Joseph R. Tufts,Marsha J. Wolf,J. Brinkmann,Istvan Csabai,G. S. Hennessy,Donald G. York
Physics , 2001, DOI: 10.1086/338095
Abstract: Low dispersion optical spectra have been obtained with the Hobby-Eberly Telescope of 22 very red objects found in early imaging data from the Sloan Digital Sky Survey. The objects are assigned spectral types on the 2MASS system (Kirkpatrick et al. 1999) and are found to range from late M to late L. The red- and near-infrared colors from SDSS and 2MASS correlate closely with each other, and most of the colors are closely related to spectral type in this range; the exception is the (i^* - z^*) color, which appears to be independent of spectral type between about M7 and L4. The spectra suggest that this independence is due to the disappearance of the TiO and VO absorption in the i-band for later spectral types; to the presence of strong Na I and K I absorption in the i-band; and to the gradual disappearance of the 8400 Angstrom absorption of TiO and FeH in the z-band.
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data II: The Spring Equatorial Stripe  [PDF]
SDSS Collaboration,Xiaohui Fan
Physics , 1999, DOI: 10.1086/301191
Abstract: This is the second paper in a series aimed at finding high-redshift quasars from five-color (u'g'r'i'z') imaging data taken along the Celestial Equator by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. In this paper, we present 22 high-redshift quasars (z>3.6) discovered from ~250 deg^2 of data in the spring Equatorial Stripe, plus photometry for two previously known high-redshift quasars in the same region of sky. Our success rate of identifying high-redshift quasars is 68%. Five of the newly discovered quasars have redshifts higher than 4.6 (z=4.62, 4.69, 4.70, 4.92 and 5.03). All the quasars have i* < 20.2 with absolute magnitude -28.8 < M_B < -26.1 (h=0.5, q_0=0.5). Several of the quasars show unusual emission and absorption features in their spectra, including an object at z=4.62 without detectable emission lines, and a Broad Absorption Line (BAL) quasar at z=4.92.
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data  [PDF]
SDSS Collaboration,X. Fan
Physics , 1999, DOI: 10.1086/300944
Abstract: We present photometric and spectroscopic observations of 15 high-redshift quasars (z > 3.6) discovered from ~140 deg^2 of five-color (u'g'r'i'z') imaging data taken by the Sloan Digital Sky Survey (SDSS) during its commissioning phase. The quasars are selected by their distinctive colors in SDSS multicolor space. Four of the quasars have redshifts higher than 4.6 (z=4.63, 4.75, 4.90 and 5.00, the latter being the highest redshift quasar yet known). In addition, two previously known z > 4 objects were recovered from the data. The quasars all have i* < 20 and have luminosities comparable to that of 3C273. The spectra of the quasars have similar features (strong, broad emission lines and substantial absorption blueward of the Ly alpha emission line) seen in previously known high-redshift quasars. Although the photometric accuracy and image quality fail to meet the final survey requirements, our success rate for identifying high-redshift quasars (17 quasars from 27 candidates) is much higher than that of previous multicolor surveys. However, the numbers of high-redshift quasars found is in close accord with the number density inferred from previous surveys.
Candidate RR Lyrae Stars Found in Sloan Digital Sky Survey Commissioning Data  [PDF]
Z. Ivezic,J. Goldston,K. Finlator
Physics , 2000, DOI: 10.1086/301455
Abstract: We present a sample of 148 candidate RR Lyrae stars selected from Sloan Digital Sky Survey (SDSS) commissioning data for about 100 deg2 of sky surveyed twice with Delta(t) = 1.9946 days. Although the faint magnitude limit of the SDSS allows us to detect RR Lyrae stars to large galactocentric distances (about 100 kpc, or r = 21), we find no candidates fainter than r = 20, i.e. further than about 65 kpc from the Galactic center. On the assumption that all 148 candidates are indeed RR Lyrae stars (contamination by other species of variable star is probably less than 10%), we find that their volume density has roughly a power-law dependence on galactocentric radius, 1/R^(2.7+-0.2), between 10 and 50 kpc, and drops abruptly at R = 50-60 kpc, possibly indicating a sharp edge to the stellar halo as traced by RR Lyrae stars. The Galactic distribution of stars in this sample is very inhomogeneous and shows a clump of over 70 stars at about 45 kpc from the Galactic center. This clump is also detected in the distribution of nonvariable objects with RR Lyrae star colors. When sources in the clump are excluded, the best power-law fit becomes consistent with the 1/R^3 distribution found from surveys of bright RR Lyrae stars. These results imply that the halo contains clumpy overdensities inhomogeneously distributed within a smooth 1/R^3 background, with a possible cutoff at about 50 kpc.
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data V. Hobby-Eberly Telescope Observations  [PDF]
Donald P. Schneider,Xiaohui Fan,Michael A. Strauss,James E. Gunn,Gordon T. Richards,Gary J. Hill,Phillip J. MacQueen,Lawrence W. Ramsey
Physics , 2000, DOI: 10.1086/319422
Abstract: We report the discovery of 27 quasars with redshifts between 3.58 and 4.49. The objects were identified as high-redshift candidates based on their colors in Sloan Digital Sky Survey commissioning data. The redshifts were confirmed with low resolution spectra obtained at the Hobby-Eberly Telescope. The quasars' $i^*$ magnitudes range from 18.55 to 20.97. Nearly 60% of the quasar candidates observed are confirmed spectroscopically as quasars. Two of the objects are Broad Absorption Line quasars, and several other quasars appear to have narrow associated absorption features.
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data VI. Sloan Digital Sky Survey Spectrograph Observations  [PDF]
Scott F. Anderson,Xiaohui Fan,Gordon T. Richards,Donald P. Schneider,Michael A. Strauss,Daniel E. Vanden Berk,James E. Gunn
Physics , 2001, DOI: 10.1086/321168
Abstract: We present results on over 100 high-redshift quasars found in the Sloan Digital Sky Survey (SDSS), using automated selection algorithms applied to SDSS imaging data and with spectroscopic confirmation obtained during routine spectroscopic operations of the Sloan 2.5-m telescope. The SDSS spectra cover the wavelength range 3900--9200 Angstroms at a spectral resolution of 1800, and have been obtained for 116 quasars with redshifts greater than 3.94; 92 of these objects were previously uncataloged, significantly increasing the current tally of published z>4 quasars. The paper also reports observations of five additional new z>4.6 quasars; all were found from the SDSS imaging survey and spectroscopically confirmed with data from the Apache Point Observatory's 3.5-m telescope. The i' magnitudes of the quasars range from 18.03 to 20.56. Of the 97 new objects in this paper, 13 are Broad Absorption Line quasars. Five quasars, including one object at a redshift of 5.11, have 20 cm peak flux densities greater than 1 mJy. Two of the quasars, both at z=4.5, have very weak emission lines; one of these objects is a radio source. Nineteen of the newly-discovered objects have redshifts above 4.6, and the maximum redshift is z=5.41; among objects reported to date, the latter is the third highest redshift AGN, and penultimate in redshift among luminous quasars.
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data IV: Luminosity Function from the Fall Equatorial Stripe Sampl  [PDF]
X. Fan,M. A. Strauss,D. P. Schneider,J. E. Gunn,R. H. Lupton,R. H. Becker,M. Davis,J. A. Newman,G. T. Richards,R. L. White
Physics , 2000, DOI: 10.1086/318033
Abstract: This is the fourth paper in a series aimed at finding high-redshift quasars from five-color imaging data taken along the Celestial Equator by the SDSS. during its commissioning phase. In this paper, we use the color-selected sample of 39 luminous high-redshift quasars presented in Paper III to derive the evolution of the quasar luminosity function over the range of 3.6
The Discovery of a Second Field Methane Brown Dwarf from Sloan Digital Sky Survey Commissioning Data  [PDF]
SDSS Collaboration,Zlatan I. Tsvetanov
Physics , 2000, DOI: 10.1086/312515
Abstract: We report the discovery of a second field methane brown dwarf from the commissioning data of the Sloan Digital Sky Survey (SDSS). The object, SDSS J134646.45-003150.4 (SDSS 1346-00), was selected because of its very red color and stellar appearance. Its spectrum between 0.8-2.5 mic is dominated by strong absorption bands of H_2O and CH_4 and closely mimics those of Gliese 229B and SDSS 162414.37+002915.6 (SDSS 1624+00), two other known methane brown dwarfs. SDSS 1346-00 is approximately 1.5 mag fainter than Gliese 229B, suggesting that it lies about 11 pc from the sun. The ratio of flux at 2.1 mic to that at 1.27 mic is larger for SDSS 1346-00 than for Gliese 229B and SDSS 1624+00, which suggests that SDSS 1346-00 has a slightly higher effective temperature than the others. Based on a search area of 130 sq. deg. and a detection limit of z* = 19.8, we estimate a space density of 0.05 pc^-3 for methane brown dwarfs with T_eff ~ 1000 K in the 40 pc^3 volume of our search. This estimate is based on small-sample statistics and should be treated with appropriate caution.
High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data III: A Color Selected Sample at i^*<20 in the Fall Equatorial Stripe  [PDF]
X. Fan,M. A. Strauss,G. T. Richards,J. A. Newman,R. H. Becker,D. P. Schneider,J. E. Gunn,M. Davis,R. L. White,R. H. Lupton
Physics , 2000, DOI: 10.1086/318032
Abstract: This is the third paper in a series aimed at finding high-redshift quasars from five-color (u'g'r'i'z') imaging data taken along the Celestial Equator by the SDSS during its commissioning phase. In this paper, we first present the observations of 14 bright high-redshift quasars (3.66
Magnetic white dwarfs in the Early Data Release of the Sloan Digital Sky Survey  [PDF]
B. T. Gaensicke,F. Euchner,S. Jordan
Physics , 2002, DOI: 10.1051/0004-6361:20021225
Abstract: We have identified 7 new magnetic DA white dwarfs in the Early Data Release of the Sloan Digital Sky Survey. Our selection strategy has also recovered all the previously known magnetic white dwarfs contained in the SDSS EDR, KUV03292+0035 and HE0330-0002. Analysing the SDSS fibre spectroscopy of the magnetic DA white dwarfs with our state-of-the-art model spectra, we find dipole field strengths 1.5<=B_d<=63MG and effective temperatures 8500<=Teff<=39000K. As a conservative estimate, we expect that the complete SDSS will increase the number of known magnetic white dwarfs by a factor 3.
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