The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed investigations of the distribution of luminous and non- luminous matter in the Universe: a photometrically and astrometrically calibrated digital imaging survey of pi steradians above about Galactic latitude 30 degrees in five broad optical bands to a depth of g' about 23 magnitudes, and a spectroscopic survey of the approximately one million brightest galaxies and 10^5 brightest quasars found in the photometric object catalog produced by the imaging survey. This paper summarizes the observational parameters and data products of the SDSS, and serves as an introduction to extensive technical on-line documentation.Comment: 9 pages, 7 figures, AAS Latex. To appear in AJ, Sept 200

The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere and collect spectra of %10 6 galaxies, 100,000 quasars, 30,000 stars, and 30,000 serendipity targets. In 2001 June, the SDSS released to the general astronomical community its early data release, roughly 462 deg 2 of imaging data including almost 14 million detected objects and 54,008 follow-up spectra. The imaging data were collected in drift-scan mode in five bandpasses (u, g, r, i, and z); our 95% completeness limits for stars are 22.0, 22.2, 22.2, 21.3, and 20.5, respectively. The photometric calibration is reproducible to 5%, 3%, 3%, 3%, and 5%, respectively. The spectra are flux-and wavelength-calibrated, with 4096 pixels from 3800 to 9200 Å at R % 1800. We present the means by which these data are distributed to the astronomical community, descriptions of the hardware used to obtain the data, the software used for processing the data, the measured quantities for each observed object, and an overview of the properties of this data set.

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We investigate the photometric properties of 456 bright galaxies using imaging data recorded during the commissioning phase of the Sloan Digital Sky Survey (SDSS). Morphological classification is carried out by correlating results of several human classifiers. Our purpose is to examine the statistical properties of color indices, scale lengths, and concentration indices as functions of morphology for the SDSS photometric system. We find that u ′ −g ′ , g ′ −r ′ , and r ′ −i ′ colors of SDSS galaxies match well with those expected from the synthetic calculation of spectroscopic energy distribution of template galaxies and with those transformed from UBV R C I C color data of nearby galaxies. The agreement is somewhat poor, however, for i ′ − z ′ color band with a discrepancy of 0.1 − 0.2 mag. With the aid of the relation between surface brightness and radius obtained by Kent (1985), we estimate the averages of the effective radius of early type galaxies and the scale length of exponential disks both to be 2.6 kpc for L * galaxies. We find that the half light radius of galaxies depends slightly on the color bands, consistent with the expected distribution of star-forming regions for late type galaxies and with the known color gradient for early type galaxies. We also show that the (inverse) concentration index, defined by the ratio of the half light Petrosian radius to the 90% light Petrosian radius, correlates tightly with the morphological type; this index allows us to classify 1 Based on observations obtained with the Sloan Digital Sky Survey galaxies into early (E/S0) and late (spiral and irregular) types, allowing for a 15-20% contamination from the opposite class compared with eye-classified morphology.

SummaryThe epidermis of higher plants generates the cuticle layer that covers the outer surface of each plant. The cuticle plays a crucial role in plant development, and some mutants with defective cuticle exhibit morphological abnormalities, such as the fusion of organs. The way in which the cuticle forms and its contribution to morphogenesis are poorly understood. Conventional detection of the cuticle by transmission electron microscopy (TEM) requires laborious procedures, which include ®xation, staining with osmium, and preparation of ultra-thin sections. It is also dif®cult to survey entire surfaces of expanded leaves because of the limited size of specimens that can be examined. Thus, TEM is unsuitable for large-scale screening for mutants with defective cuticle. We describe here a rapid and inexpensive method, designated the toluidine-blue (TB) test, for detection of cuticular defects in whole leaves. We demonstrated the validity of the TB test using mutants of Arabidopsis thaliana, including abnormal leaf shape1 (ale1), ®ddlehead (fdh), and ®ve eceriferum (cer) mutants, in which the structure and/or function of the cuticle is abnormal. Genetic screening for mutants using the TB test allowed us to identify seven loci. The cuticle-defective regions of leaves of the mutants revealed ®ve intrinsic patterns of surface defects (classes I through V), suggesting that formation of functional cuticle on leaves involves various spatially regulated factors.