THE NINTH DATA RELEASE OF THE SLOAN DIGITAL SKY SURVEY: FIRST SPECTROSCOPIC DATA FROM THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY

The Sloan Digital Sky Survey III (SDSS-III; Eisenstein et al. 2011) is an extension of the SDSS-I and II projects (York et al. 2000). It uses the dedicated 2.5 m wide-field Sloan Foundation Telescope (Gunn et al. 2006) at Apache Point Observatory (APO), and fiber-fed multi-object spectrographs to carry out four surveys to study dark energy through observations of distant galaxies and quasars (the Baryon Oscillation Sky Survey, BOSS), to understand the structure of the Milky Way Galaxy (SEGUE-2; and APOGEE), and to search for extrasolar planets (MARVELS). SDSS-III commenced in Fall 2008, and will carry out observations for six years through Summer 2014. The first data release of this phase of SDSS (and the eighth release overall, DR8; Aihara et al. 2011a) was made public in Winter 2011. In addition to all the data from SDSS-I and II (Abazajian et al. 2009), DR8 included additional five-band imaging data over 2500 deg² over the Southern Galactic Cap, as well as stellar spectra from SEGUE-2.

This paper presents the ninth data release (DR9) from SDSS, including all survey-quality data from BOSS gathered through 2011 July. BOSS (Dawson et al. 2012) uses new spectrographs (Smee et al. 2012) to obtain spectra of galaxies with 0.15 < z < 0.8 and quasars with 2.15 < z < 3.5 to measure the scale of the baryon oscillation peak in the correlation function of matter in order to probe the geometry and dynamics of the universe. DR9 includes the first year of BOSS data, and this paper describes the characteristics of these data (summarized in Section 2), with a particular emphasis on how it differs from the spectroscopy carried out in SDSS-I and SDSS-II (Section 3).

The erratum to the DR8 paper (Aihara et al. 2011b) describes a systematic error in the astrometry in the imaging catalogs in DR8. This has now been fixed, as we describe in Section 4.

The SEGUE Stellar Parameters Pipeline (SSPP) fits detailed models to the spectrum of each star, to determine surface temperatures, metallicities, and gravities. It has been continuously improved since its introduction in the sixth data release (DR6; Adelman-McCarthy et al. 2008; see also Lee et al. 2008a). In Section 5, we describe the improvements since DR8 that are incorporated into the DR9 outputs.

Section 6 describes how one can access the DR9 data, and we conclude and outline the planned future data releases in Section 7.

DR9 presents the release of the first 1.5 years of data from the SDSS-III BOSS spectroscopic survey. BOSS started commissioning in early Fall 2009, and began survey-quality observations on the night of 2009 December 5 (UTC-7; MJD 55171). All processed data from that date until the summer telescope shutdown⁹⁸ in 2011 July are included in DR9. All raw data taken by the BOSS spectrograph from the start of commissioning (2009 September) up through and including 2011 July 10 (MJD 55752) are also available as flat files as part of the DR9 release, although the commissioning data are of quite poor quality, and do not always include data from both spectrographs. DR9 also includes the spectroscopic data from SDSS-I/II and SEGUE2; it is unchanged since DR8.

The details of the data included in DR9 are summarized in Table 1, and the footprints of the imaging and spectroscopic data are shown in Figure 1. The imaging data and imaging catalogs are the same as in DR8, with the key update of an improved astrometric solution to correct an error affecting objects at high declinations (Aihara et al. 2011b).

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Figure 2 presents the distribution with look-back time of spectroscopically confirmed stars, galaxies, and quasars from BOSS in the DR9 data set. Figure 3 compares these distributions to those of all previous SDSS spectra of galaxies and quasars.

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All data released with DR9 are publicly available at http://www.sdss3.org/dr9.

When the universe was radiation-dominated, sound waves propagated through the radiation–matter fluid at a significant fraction of the speed of light. They slowed dramatically after matter–radiation equality, and were frozen in after recombination. Sound waves emanating from overdensities thus traveled a given distance, roughly 150 comoving Mpc (given standard cosmological parameters) from the initial perturbations; the resulting overdensity gives an excess in the clustering of matter at this scale. This is the origin of the oscillations seen in the power spectrum of the cosmic microwave background (e.g., Komatsu et al. 2011), and was first conclusively seen in the clustering of galaxies from the Two Degree Field Galaxy Redshift Survey (Cole et al. 2005) and the SDSS (Eisenstein et al. 2005). This feature in the galaxy or matter correlation function or power spectrum is a standard ruler; measuring it as a function of redshift gives a powerful constraint on cosmological models (e.g., Weinberg et al. 2012).

The initial SDSS detection of the baryon oscillation feature (Eisenstein et al. 2005; see also Tegmark et al. 2006; Percival et al. 2010; Padmanabhan et al. 2012) was based upon a galaxy sample with effective mean redshift z ∼ 0.35. BOSS aims to measure spectra (and thus redshifts) for a sample of 1.5 million galaxies extending to z = 0.8 over 10,000 deg², to use the baryon oscillation feature to make a 1% measurement of the angular diameter distance at z = 0.35 and a separate uncorrelated 1% measurement at z = 0.6. In addition, 150,000 quasars with z > 2.15 will be observed to measure the clustering of the Lyα forest, and thus to determine the baryon oscillation scale at z ∼ 2.5, an epoch before dark energy dominated the expansion of the universe.

The samples of galaxies and quasars needed to carry out this program are significantly fainter than those targeted in SDSS-I and SDSS-II (Eisenstein et al. 2001; Strauss et al. 2002; Richards et al. 2002), and have a higher density on the sky. The SDSS spectrographs and supporting infrastructure were extensively rebuilt to increase throughput and observing efficiency, as described in detail in Smee et al. (2012). In particular:

• 1.  
  The optical fibers, which bring light from the focal plane to the spectrographs, subtended 3'' on the sky in SDSS-I/II. Given the smaller angular size of the higher redshift BOSS galaxy targets, the fibers now subtend 2''.
• 2.  
  The number of fibers was increased from 640 to 1000.
• 3.  
  New high-throughput volume phase holographic (VPH) gratings were installed.
• 4.  
  The optics have been replaced, with improved throughput.
• 5.  
  The CCDs were replaced, with improved response at both the blue and red limits.

The resulting spectra are broadly similar to those of SDSS-I/II, but have significantly higher signal-to-noise ratio (S/N) at a given fiber magnitude. While the resolution as a function of wavelength is similar, the spectral coverage is significantly broader, from 3600 Å to 10400 Å. Finally, the target selection algorithms for galaxies (N. Padmanabhan et al. 2013, in preparation) and quasars (Ross et al. 2012) are significantly different from those used in SDSS-I/II, given the rather different scientific goals.

The design of the BOSS survey itself is described in detail in Dawson et al. (2012). First baryon oscillation results from the DR9 galaxy sample may be found in Anderson et al. (2012) and references therein, and the first analysis of the clustering of the Lyα forest from BOSS quasar spectra is found in Slosar et al. (2011).

3.1. BOSS Main Survey Targets

3.2. Differences between SDSS-I/II Spectra and SDSS-III BOSS Spectra

Readers who are familiar with the SDSS-I/II spectra will be able to use the BOSS spectra quickly, since the twin BOSS spectrographs are upgraded versions of the original SDSS-I/II spectrographs, as described above. In addition, the pipelines used to process the BOSS spectra (D. Schlegel et al. 2012, in preparation; Bolton et al. 2012) are improved versions of those used in SDSS-I/II. In this section, we briefly outline the main differences between the BOSS spectra and the SDSS-I/II spectra. For more detailed information on the BOSS spectrographs, the reader is referred to Smee et al. (2012), while the BOSS operations are described in Dawson et al. (2012).

The BOSS spectrographs include 1000 fibers in each plate, in comparison with 640 fibers per plate in SDSS-I/II. In addition, the spectral coverage has been increased from 3800–9200 Å to 3600–10400 Å. The dichroic split between the blue and red sides occurs at roughly 6000 Å, as it was in SDSS-I/II. The expanded blue coverage means that the Cd i arc line at 3610.51 Å is now included in the wavelength calibration, enabling a more accurate wavelength solution on the blue end (see the discussion in Adelman-McCarthy et al. 2008). The median resolution of the BOSS spectra remains R = λ/Δλ ≈ 2000 as in SDSS-I/II, with a similar wavelength dependence (Smee et al. 2012); the resolution ranges from R ≈ 1500 at 3700 Å, to R ≈ 2500 at 9500 Å.

In addition, the diameter of the spectroscopic fibers in BOSS has been decreased in size from 3'' to 2''. While this improves the S/N for point-like objects and the smaller galaxies targeted by BOSS due to decreased sky background relative to the source signal, the smaller fiber size affects the spectrophotometry for galaxies, and is more subject to differential chromatic aberration and seeing effects. As in SDSS-I/II, the spectrophotometry is tied to the point-spread function (PSF) photometry of stars on each plate. In SDSS-I/II, the rms scatter between the PSF photometry and synthesized photometry from the calibrated spectra was of order 4% (Adelman-McCarthy et al. 2008); with BOSS, it is closer to 6% (Dawson et al. 2012, but see the discussion below about quasar spectrophotometry). The photometric catalog released in DR8 and DR9 (Section 6) provides the 2'' photometry (termed FIBER2MAG) for each object to complement 3'' photometry (FIBERMAG).

The more sensitive CCDs, improved throughput of the VPH gratings, and improved optics have further improved the S/N in the BOSS spectra, enabling the targeting of fainter objects. For each plate, the median log S/N per pixel within wavelength regions corresponding to the SDSS imaging bands g, r, and i (Fukugita et al. 1996) is tabulated against the corresponding 2'' fiber magnitude. A line of slope 0.3 is fit to this line, and the intercept at the fiducial magnitudes of g = 21.2, r = 20.2, and i = 20.2 is noted. This quantity is compared for SDSS DR7 and BOSS plates in Figure 4. The median exposure times of BOSS DR9 plates (1.5 hr) are only 70% longer than those in SDSS-I/II (0.89 hr), but due to the instrument upgrades, the resulting (S/N)² values of the BOSS spectra are more than twice those in SDSS-I/II at the same magnitude.

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Because one of the stated goals of the BOSS survey is to study the Lyα forest absorption in quasars, efforts have been made to improve the S/N at the blue end of the BOSS objects targeted as quasars. In particular, the focal plane of the SDSS telescope was designed to be in focus for BOSS at ∼5400 Å, whereas the z ∼ 2.5 Lyα forest lies at λ ≲ 4000 Å, a wavelength that will be out of focus and offset radially due to differential chromatic aberration. To correct for this, we have offset the quasar target fibers in both the radial and axial directions to maximize the throughput at λ ∼ 4000 Å. The radial offset was implemented by drilling the quasar plug holes at slightly different positions (depending on the assumed hour angle at which the plate will be observed), while in the axial direction we have introduced thin washers to the plug holes on the fiber side of the plates, with thicknesses of 175 and 300 μm in the regions spanning 1.02–1.34 deg and 1.34–1.50 deg radially from the plate center, respectively (Dawson et al. 2012). These offsets are tabulated in the ZOFFSET and LAMBDA_EFF flags in the survey data (Section 6).

The current pipeline flux calibration (D. Schlegel et al. 2012, in preparation) does not take these fiber offsets into account, therefore the spectrophotometry of the objects in the quasar targets is biased toward bluer colors, with excess flux relative to the SDSS imaging data at λ < 4000 Å and a flux decrement at longer wavelengths (Pâris et al. 2012). We have measured the mean difference between spectrophotometric and imaging magnitudes for those objects targeted as quasars but that turned out to be stars⁹⁹—the values are (0.11 ± 0.24, 0.16 ± 0.29, 0.24 ± 0.33) mag in (g, r, i). Objects observed at higher airmass show larger offsets.

Quasars targeted solely as part of ancillary programs were not subject to these offsets, and thus their spectrophotometry should show no significant bias. Of course, these objects will have reduced S/N in the blue. However, some quasars targeted in ancillary programs were also targets in the main CORE or BONUS samples; these ancillary quasars do have the washer offsets applied (at least after MJD 55441, when the washers were first applied; see Section 3.4 below).

DR9 includes new BOSS observations of objects observed with the previous spectrograph in SDSS-I/II. This includes 4074 galaxies, 16,967 quasars (mostly specifically re-targeted to obtain better Lyα forest measurements), and 7875 stars. The repeated galaxy and star observations confirm that the redshift scales of the two data sets are consistent within a few km s⁻¹. However, due to an updated set of quasar templates in the BOSS pipeline (Bolton et al. 2012), quasar redshifts are 175 km s⁻¹ higher in the median in BOSS than in SDSS-I/II. The limitations of the quasar redshifts in previous data releases were highlighted by Hewett & Wild (2010) in a reanalysis of DR6 quasar redshifts. While the new templates are designed to more fully represent the range of quasars found, obtaining accurate redshifts remains challenging because of the uncertainty in the relative velocity offsets of different emission lines from the rest frame of the quasar host galaxy system. See Pâris et al. (2012) and Bolton et al. (2012) for a discussion of the details and caveats of quasar redshift determination in DR9.

Figure 5 shows spectra of a galaxy and a quasar, observed both with SDSS-I/II and BOSS. This figure illustrates the greater wavelength coverage and the significantly higher S/N of the BOSS spectra for observations of the same object.

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3.3. Quantities Derived from Galaxy Spectra

3.4. Changes in BOSS Spectrographs and Survey Strategy

While commissioning of the BOSS spectrographs was completed in early 2009 December, we continued to make improvements and changes to the spectrographs, the observing system, and the exposure depths. In this section, we outline those changes that affect the DR9 data. The effects on the quality of the resulting spectra due to these changes are subtle, but the reader interested in detailed comparisons of the BOSS data as a function of time should be aware of them.

BOSS observes spectra with 15 minute exposures which are repeated until the summed signal-to-noise squared per pixel, (S/N)², reaches a given threshold in each of the four spectrograph cameras (B1, B2, R1, R2 for the blue and red arms of spectrographs 1 and 2). A quick-look pipeline runs after each exposure to estimate the accumulated (S/N)² in near real time and a plate is exposed again until given (S/N)² thresholds are reached.

For the first year of the survey BOSS conservatively observed a little deeper than was thought to be necessary, with the idea of re-evaluating and updating these (S/N)² thresholds for future years. After the first year of observations, it became clear that that we were not covering the sky sufficiently quickly to reach our goal of 10,000 deg² by the end of the survey in Summer 2014. BOSS thus conducted a review of the fiducial (S/N)² thresholds needed to optimize both survey speed and spectroscopic completeness. The decision was made to lower the (S/N)² thresholds and impose a more restrictive cut on the galaxy surface brightness faint limit. On MJD 55497 the (S/N)² thresholds were reduced from >16 to >10 for the blue spectrograph cameras (for g = 22) and from >26 to >22 for the red spectrograph cameras (for i = 21).¹⁰⁰ At the same time, the CMASS target selection limiting magnitude was changed from IFIBER2MAG <21.7 to <21.5. There is a very slight change in spectroscopic survey completeness after this date. Further details are provided in Section 5 of Dawson et al. (2012).

Improvements to the guider software were made on MJD 55253, leading to better guiding and thus improved throughput. Improvements to the field acquisition software and the efficiency of calibration observations were made on MJD 55343 and resulted in reduced observing overheads and a larger fraction of open-shutter time.

Table 2 summarizes a series of hardware changes that further improved throughput and image quality and reduced scattered light. Figure 6 demonstrates the effect on S/N of the hardware and survey strategy changes. This allowed us to reach the fiducial (S/N)² in the spectra in fewer exposures. Air bubbles had developed in the oil interfaces between the B1 triplet lenses, reducing throughput and causing scattered light. These were replaced on MJD 55520. The triplet lenses for the other spectrograph arms have also been replaced, but only after the 2011 July date that marks the end of DR9. The R2 CCD was replaced on MJD 55298 due to a hardware failure. The R1 and R2 CCD clocking was changed from one- to two-phase for charge collection on MJD 55390. The use of washers to optimize (S/N)² for quasar targets began on MJD 55441 and was fully implemented for all CORE and BONUS quasar targets starting MJD 55474. Finally, we did two rounds of adjusting the focus of the CCDs in their dewars, further improving the throughput.

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Table 2. BOSS Survey Changes

Date	MJDa	Change
2009 Aug 28	55071	Earliest BOSS commissioning data available in SAS
2009 Dec 6	55171	Beginning of survey-quality data
2010 Feb 26	55253	Installed mask in the central optics to eliminate a secondary light path that was directly imaged onto the CCD
2010 Feb 26	55253	Guider improvements
2010 Feb 26	55253	CCD dewars adjusted for better focus
2010 Mar 1	55256	Installed a collimator mask to remove light being reflected off of the slithead and re-imaged onto the CCD
2010 Apr 12	55299	R2 CCD replaced
2010 May 28	55343	Field acquisition and calibration efficiency improvements
2010 Jul 7	55384	CCD positions adjusted inside dewars for better focus
2010 Jul 13	55390	R1,R2 CCD change from one- to two-phase slightly changed effective pixel size
2010 Sep 2	55441	Washers for quasar targets, some plates
2010 Oct 5	55474	Washers for quasar targets, all plates
2010 Oct 28	55497	Changed (S/N)2 thresholds and target selection
2010 Nov 20	55520	B1 triplet lenses replaced

Note. ^aAll data taken on and after the given MJD include the respective change.

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The DR8 imaging suffered from several errors in the astrometric calibration, as described in an erratum published shortly after the DR8 release (Aihara et al. 2011b).¹⁰¹ These errors have been corrected in DR9, and the resulting astrometry and proper motions are improved relative to both DR7 and DR8.¹⁰²

The issues with the DR8 astrometry were, in brief:

• 1.  
  Northward of +41° declination there was an offset of 250 mas introduced by switching from the Second US Naval Observatory CCD Astrograph Catalog (UCAC2; Zacharias et al. 2004) to the United States Naval Observatory (USNO)-B catalog (Monet et al. 2003) at this declination.
• 2.  
  Color terms were not used in calculating CCD position to sky position, introducing systematic errors of 10–20 mas.
• 3.  
  UCAC2 proper motions were not applied correctly, introducing further errors of order 5–10 mas.
• 4.  
  Stellar positions were always measured in the r-band photometry, even if the r band was saturated or had a lower S/N detection than other filters. For faint objects this increases the statistical uncertainty for the measurement, but for r-band saturated objects the difference can be as much as 100 mas between using r-band positions and those in non-saturated filters.

All of these issues have been corrected for DR9. The discovery of the mistakes in DR8 prompted the development of a new set of astrometric quality-assurance metrics that are fully described in the SDSS-III DR9 data model.¹⁰³

With these problems corrected, the DR9 astrometry fixes errors in both DR8 and DR7. In particular, DR7 contained very large errors in a handful of runs (3358, 4829, 5960, 6074, and 6162) that are corrected in DR9 (the most prominent of these is the black and white arc in the upper central region of the top panels of Figure 7).

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Proper motions in DR9 are similarly improved relative to DR8 and DR7. As Figure 7 shows, they are mostly unchanged in the mean at high Galactic latitudes. However, the corrected color terms in the astrometry have fixed a small fraction of objects with outlying proper motions in the DR9 relative to DR8 (this error did not affect DR7 or earlier). Furthermore, at low Galactic latitudes DR7 had some large offsets caused by star–galaxy separation errors. Proper motions are measured with respect to a reference frame of stationary galaxies, so stellar contamination in the galaxy sample can systematically affect the proper-motion estimates. In DR7, errors in star–galaxy separation (in particular in photometric rerun 648) caused the galaxy sample to have significant stellar contamination, leading to systematic errors in the proper motions. DR9 fixes this problem.

The proper motions can be independently tested by looking at the proper motions of photometrically identified low-redshift quasars, which are easy to select and should have zero proper motions. Figure 8 shows the proper motions of the low-redshift quasars as selected by Bovy et al. (2011). These show very little systematic offset from zero, except for a small shift in μ_δ at low declination. This offset is further described by Bond et al. (2010) in the context of the DR7 proper motions, and could be due to small differential refraction correction issues in USNO-B for these very blue objects (and is therefore likely not relevant to the proper motions of typical stars).

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The SSPP (Lee et al. 2008a, 2008b; Allende Prieto et al. 2008; Smolinski et al. 2011) utilizes multiple approaches to estimate effective temperature (T_eff), surface gravity (log g), and metallicity ([Fe/H]) from stellar spectra. Each method is optimized for a certain range of stellar color (g − r) and S/N, and is measured over a range of wavelengths determined to deliver the best estimate of each parameter. The SSPP is designed to obtain reliable results for stars targeted as part of the SDSS-II SEGUE and SDSS-III SEGUE-2 surveys (C. Rockosi et al. 2012, in preparation). With each SDSS data release the SSPP has been refined and modified to provide more accurate estimates of the stellar atmospheric parameters. Here we briefly highlight major changes and improvements made since the DR8 public release that are used for the DR9 data.

A sample of 126 high-resolution spectra of SDSS/SEGUE stars, taken with Keck, Subaru, the Hobby–Eberly Telescope, and the Very Large Telescope, have been analyzed in a homogeneous fashion, and a new set of stellar parameters were obtained from this analysis (Allende Prieto et al. 2008; Smolinski et al. 2011). The sample covers 4000 K < T_eff < 7000 K, 0.0 < log g < 5.0, and −4.0 < [Fe/H] <+0.5. However, this data set contains no metal-poor ([Fe/H] <−2.5) dwarfs or metal-rich ([Fe/H] >0.0) giants. Additional information on this high-resolution sample can be found in Allende Prieto et al. (2008) and Smolinski et al. (2011).

The individual methods in the SSPP, in particular estimates of surface gravity and metallicity, have been thoroughly re-calibrated based on these new data. The SSPP also adopts a much-improved color (g − r)-temperature relation, the InfraRed Flux Method (IRFM) as described by Casagrande et al. (2010). Each SSPP temperature estimate was re-scaled to match the IRFM temperature estimate. This technique particularly improves the temperature estimates for cool stars (T_eff < 5000 K).

Figure 9 shows the results of the comparisons of the SSPP parameters with the IRFM for temperature, and the high-resolution analysis for gravity and metallicity. Implementation of a grid of synthetic spectra with microturbulences that vary appropriately with surface gravity also yields improved estimates of metallicity for metal-rich stars ([Fe/H] >−0.5).

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A parameter comparison from a sample of about 9000 multiply observed stellar spectra in SEGUE provides the basis for an estimate of the internal uncertainties of the SSPP: ∼50 K for T_eff, ∼0.12 dex for log g, and ∼0.10 dex for [Fe/H] for a typical G-type dwarf or redder stars in the color range of 0.4 < g − r < 1.3 with S/N per pixel = 30. These errors increase to ∼80 K, 0.30 dex, and 0.25 dex for T_eff, log g, and [Fe/H], respectively, for stars with −0.3 < g − r < 0.2, [Fe/H] <−2.0, and S/N <15.

A comparison with the DR8 parameters for stars from SEGUE-1 indicates that the DR9 average T_eff is higher by ∼60 K, the DR9 log g is lower by ∼0.2 dex, and the metallicity does not change significantly, although these values vary with spectral type and spectral S/N.

These new SSPP results are made available for all stars in SDSS-I/II, including those of SEGUE-1 (Yanny et al. 2009), and the SEGUE-2 stars in SDSS-III. SSPP measurements are not currently available for the stars observed as part of BOSS, although we plan to include that in future data releases.

All Data Release 9 data are available through data access tools linked from the DR9 Web site.¹⁰⁴ The data are stored both as flat files in the Science Archive Server (SAS),¹⁰⁵ and as a searchable database in the Catalog Archive Server (CAS). A number of different interfaces are available, each designed to accomplish a specific task: (1) color images of regions of the sky in JPEG format (based on the g, r, and i images; see Lupton et al. 2004) can be viewed in a Web browser with the SkyServer Navigate tool; (2) FITS images can be downloaded through the SAS; (3) complete catalog information (astrometry, photometry, etc.) of any imaging object can be viewed through the SkyServer Explore tool; and (4) FITS files of the spectra can be downloaded through the SAS.

In addition, a number of catalog search tools are available through the SkyServer interface to the CAS, each of which returns catalog data for objects that match supplied criteria. For more advanced queries, a powerful and flexible catalog search Web site called "CasJobs" allows users to create their own personalized data sets and then to modify or graph their data.

The DR9 Web site also features data access tutorials, a glossary of SDSS terms, and detailed documentation about algorithms used to process the imaging and spectroscopic data and select spectroscopic targets.

Imaging and spectroscopic data from all prior data releases are also available through DR9 data access tools.

The SDSS-III Data Release 9 presents the first data from the BOSS survey, with ∼102,000 new quasar spectra, ∼91,000 new stellar spectra, and ∼536,000 new galaxy spectra. The astrometry has been improved since DR8, and the stellar properties for SEGUE-I/II and SDSS-I/II stars have been updated.

These data are already sufficient for cosmological analyses of large-scale structure, investigations of the structure of the Milky Way, measurements of quasar physics, clustering, and demographics, and countless other science investigations. We invite the larger scientific community to investigate and explore this new data set.

The SDSS-III project will present two more public data releases. DR10, in Summer 2013, will include the first data from the APOGEE survey and another year of BOSS data. DR11 will be an internal release only, as a public release would occur only six months before the final public data release for SDSS-III, DR12, which will be released in 2014 December and will contain all of the data taken during the six years of the project.

Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III Web site is http://www.sdss3.org/.

SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, University of Cambridge, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.