The Sloan Digital Sky Survey V (SDSS-V) is an all-sky spectroscopic survey of more than 6 million objects, designed to decode the history of the Milky Way, reveal the inner workings of stars, investigate the origin of solar systems, and track the growth of supermassive black holes across the Universe. SDSS-V presents significant innovations in both hardware and software, chiefly due to the introduction of a robotic Focal Plane System (FPS) that replaces plug-plate operations. This new mode of operations introduces new challenges with respect to target scheduling, fibre robot positioner reconfiguration optimisation, telescope guiding, observer interfaces, and observatory operations. During normal operations SDSS-V will observe a new field every 15 minutes. For each field requiring a new telescope pointing the FPS will reconfigure 500 robotic fibre positioners with feedback from an external Field Viewing Camera (FVC) in less than two minutes. Six CCD cameras mounted on the FPS will be used to automatically acquire the field and maintain the necessary guiding accuracy. These strict requirements highlight the need for streamlined operations software and procedures to minimise the time spent during FPS reconfigurations. We describe the overall design and implementation of the SDSS-V survey operations, with special emphasis on software development, conventions, and observing procedures. While specific to SDSS-V, the solutions we describe can be readily applied to other astronomical surveys and are of special interest given the rapid increase in projects employing robotic fibre positioners.

We present an overview of best practices for publishing data in astronomy and astrophysics journals. These recommendations are intended as a reference for authors to help prepare and publish data in a way that will better represent and support science results, enable better data sharing, improve reproducibility, and enhance the reusability of data. Observance of these guidelines will also help to streamline the extraction, preservation, integration and cross-linking of valuable data from astrophysics literature into major astronomical databases, and consequently facilitate new modes of science discovery that will better exploit the vast quantities of panchromatic and multidimensional data associated with the literature. We encourage authors, journal editors, referees, and publishers to implement the best practices reviewed here, as well as related recommendations from international astronomical organizations such as the International Astronomical Union for publication of nomenclature, data, and metadata. A convenient Checklist of Recommendations for Publishing Data in the Literature (Appendix A) is included for authors to consult before the submission of the final version of their journal articles and associated data files. We recommend that publishers of journals in astronomy and astrophysics incorporate a link to this document in their Instructions to Authors.

We define a large sample of galaxies for use in a study of the fundamental plane in the intermediate redshift cluster Cl 1358 + 62 at z = 0.33. We have analyzed high-resolution spectra for 55 members of the cluster. The data were acquired with the Low-Resolution Imaging Spectrograph on the Keck 1 10 m telescope. A new algorithm for measuring velocity dispersions is presented and used to measure the internal kinematics of the galaxies. This algorithm has been tested against the Fourier fitting method so that the data presented here can be compared with those measured previously in nearby galaxies. We have measured central velocity dispersions suitable for use in a fundamental plane analysis. The data have a high signal-to-noise ratio (S/N) and the resulting random errors on the dispersions are very low, typically less that 5%. Uncertainties due to mismatch of the stellar templates have been minimized through several tests, and the total systematic error is of order similar to 5%. Good seeing enabled us to measure velocity dispersion profiles and rotation curves for most of the sample, and although a large fraction of the galaxies display a high level of rotation, the gradients of the total second moment of the kinematics are all very regular and similar to those in nearby galaxies. We conclude that the data therefore can be reliably corrected for aperture size in a manner consistent with nearby galaxy samples.

Using wide-field, two-color Hubble Space Telescope (HST) imaging of the cluster Cl 1358 + 62 (z = 0.33), we derive structural parameters for a large, magnitude-limited sample of cluster members. These structural parameters are combined with accurate velocity dispersions in another paper to investigate the fundamental plane in the cluster. We fit integrated r(1/4) laws to the integrated surface brightness profiles and fit two-dimensional r(1/4)-law model galaxies to the images directly. A comparison of the results from the two methods shows that the derived half-light radii, r(e), agree very well, with an rms scatter of only 13%. The half-light radii range from approximately 1 to 20 kpc with a median of about 3 kpc (H(0) = 65 km s(-1) Mpc(-1), q(0) = 0.1).

We present a compilation of Cepheid distance moduli and data for four secondary distance indicators that employ stars in the old stellar populations: the planetary nebula luminosity function (PNLF), the globular cluster luminosity function (GCLF), the tip of the red giant branch (TRGB), and the surface brightness fluctuation (SBF) method. The database includes all data published as of 1999 July 15. The main strength of this compilation resides in the fact that all data are on a consistent and homogeneous system: all Cepheid distances are derived using the same calibration of the period-luminosity relation, the treatment of errors is consistent for all indicators, and measurements that are not considered reliable are excluded. As such, the database is ideal for comparing any of the distance indicators considered, or for deriving a Cepheid calibration to any secondary distance indicator, such as the Tully-Fisher relation, the Type Ia supernovae, or the fundamental plane for elliptical galaxies. This task has already been undertaken by Ferrarese et at, Sakai et al., Kelson et al., and Gibson et al. Specifically the database includes (1) Cepheid distances, extinctions, and metallicities; (2) reddened apparent lambda 5007 Angstrom magnitudes of the PNLF cutoff; (3) reddened apparent magnitudes and colors of the turnover of the GCLF (in both the V and B bands); (4) reddened apparent magnitudes of the TRGB (in the I band) and V-I colors at 0.5 mag fainter than the TRGB; and (5) reddened apparent surface brightness fluctuation magnitudes measured in Kron-Cousin I, K', and K-short, and using the F814W filter with the Hubble Space Telescope (HST) WFPC2. In addition, for every galaxy in the database we give reddening estimates from IRAS/DIRBE as well as H I maps, J2000 coordinates, Hubble and T-type morphological classification, apparent total magnitude in B, and systemic velocity.

The evolution of galaxies is likely to be complex, involving mergers, starbursts, and other dramatic changes in morphology and luminosity. The measurement of the evolution of the mass function of galaxies is therefore essential. This can be accomplished by measuring the evolution of the mass-to-light ratios of galaxies as a function of redshift. The Fundamental Plane relation is uniquely suited to measure the evolution of the mass-to-light ratio of early-type galaxies. We show that the evolution depends sensitively on cosmology and star-formation history. We present results on the evolution of the mass-to-light ratio from the Fundamental Plane out to z = 0.83. The early-type galaxies in clusters follow a well-defined relation out the highest redshift. The mass-to-light evolution is very slow, and implies a high mean stellar age in an open universe.

We present a study of 81 I-band selected, spectroscopically confirmed members of the X-ray cluster MS 1054-03 at z = 0.83. Redshifts and spectral types were determined from Keck spectroscopy. Morphologies and accurate colors were determined from a large mosaic of HST WFPC2 images in R-F606W and I-F814W, corresponding to U and B in the rest frame. Early-type galaxies constitute only 44% of this galaxy population. This fraction is much lower than in comparable rich clusters at low redshift. Thirty-nine percent are spiral galaxies, and 17% are mergers. The early-type galaxies follow a tight and well-defined color-magnitude relation, with the exception of a few outliers. The observed scatter is 0.029 +/- 0.005 mag in rest frame U-B. Most of the mergers lie close to the CM relation defined by the early-type galaxies. They are bluer by only 0.07 +/- 0.02 mag, and the scatter in their colors is 0.07 +/- 0.04 mag. Spiral galaxies in MS 1054-03 exhibit a large range in their colors. The bluest spiral galaxies are similar to 0.7 mag bluer than the early-type galaxies, but the majority is within +/-0.2 mag of the early-type galaxy sequence. The red colors of the mergers and the majority of the spiral galaxies are reflected in the fairly low Butcher-Oemler blue fraction of MS 1054-03: f(B) = 0.22 +/- 0.05, similar to intermediate redshift clusters and much lower than previously reported values for clusters at z similar to 0.8. The slope and scatter of the CM relation of early-type galaxies are roughly constant with redshift, confirming previous studies that were based on ground-based color measurements and very limited membership information. However, the scatter in the combined sample of early-type galaxies and mergers (i.e., the sample of future early-type galaxies) is twice as high as the scatter of the early-type galaxies alone. This is a direct demonstration of the "progenitor bias": high-redshift early-type galaxies seem to form a homogeneous, old population because the progenitors of the youngest present-day early-type galaxies are not included in the sample.

We present new results from a systematic study of absorption-line strengths of galaxies in clusters approaching redshifts of unity. In this Letter, we specifically compare the strengths of the high-order Balmer absorption features of H gamma and H delta in E/SO galaxies in the four clusters Abell 2256 (z = 0.06), Cl 1358+62 (z = 0.33), MS 2053 -04 (z = 0.58), and MS 1054-03 (z = 0.83). By comparing the correlation of the Balmer line strengths with the velocity dispersions for E/SO galaxies in the four clusters, we find moderate evolution in the zero point of the (H delta (A)+ H gamma (A))-sigma relation with redshift. The trend is consistent with the passive evolution of old stellar populations. Under the assumption that the samples can be compared directly, we use single-burst stellar population synthesis models to constrain the last major occurrences of star formation in the observed E/SO galaxies to be z(f) > 2.5 (95% confidence). We have compared the evolution of the Balmer absorption with the evolution of the B-band fundamental plane and find that simple stellar population models agree very well with the data. While the best agreement occurs with a low value for Omega (m), the data provide strong confirmation of the time evolution in recent stellar population models.

We study the fundamental plane (FP) of field early-type galaxies at intermediate redshift, using Hubble Space Telescope Wide Field Planetary Camera 2 observations and deep Keck spectroscopy. Structural parameters and internal velocity dispersions are measured for 18 galaxies at 0.15 < z < 0.55. Rest-frame M/L-B ratios are determined from the FP and compared to those of cluster early-type galaxies at the same redshifts. The systematic offset between MIL ratios of field and cluster early-type galaxies at intermediate redshift is small and not significant: [ln M/L-B](field) - [ln M/L-B](clus) = -0.18 +/- 0.11. The M/L-B ratio of field early-type galaxies evolves as Delta ln M/L-B = (-1.35 +/- 0.35)z, very similar to cluster early-type galaxies. After correcting for luminosity evolution, the FP of field early-type galaxies has a scatter sigma = 0.09 +/- 0.02 in log r(e), similar to that in local clusters. The scatter appears to be driven by low-mass S0 galaxies; for the elliptical galaxies alone we find a = 0.03(-0.03)(+0.04). There is a hint that the FP has a different slope than in clusters, but more data are needed to confirm this. The similarity of the MIL ratios of cluster and field early-type galaxies provides a constraint on the relative ages of their stars. At (z) = 0.43, held early-type galaxies are younger than cluster early-type galaxies by only 21% +/- 13%, and we infer that the stars in field early-type galaxies probably formed at z greater than or equal to 1.5. Recent semianalytical models for galaxy formation in a Lambda CDM universe predict a systematic difference between held and cluster galaxies of Delta ln M/L-B similar to -0.6, much larger than the observed difference. This result is consistent with the hypothesis that field early-type galaxies formed earlier than predicted by these models.

We present here the final results of the Hubble Space Telescope (HST) Key Project to measure the Hubble constant. We summarize our method, the results, and the uncertainties, tabulate our revised distances, and give the implications of these results for cosmology. Our results are based on a Cepheid calibration of several secondary distance methods applied over the range of about 60-400 Mpc. The analysis presented here benefits from a number of recent improvements and refinements, including (1) a larger LMC Cepheid sample to define the fiducial period-luminosity (PL) relations, (2) a more recent HST Wide Field and Planetary Camera 2 (WFPC2) photometric calibration, (3) a correction for Cepheid metallicity, and (4) a correction for incompleteness bias in the observed Cepheid PL samples. We adopt a distance modulus to the LMC (relative to which the more distant galaxies are measured) of mu (o)(LMC) = 18.50 +/- 0.10 mag, or 50 kpc. New, revised distances are given for the 18 spiral galaxies for which Cepheids have been discovered as part of the Key Project, as well as for 13 additional galaxies with published Cepheid data. The new calibration results in a Cepheid distance to NGC 4258 in better agreement with the maser distance to this galaxy. Based on these revised Cepheid distances, we find values (in km s(-1) Mpc(-1)) of H-o = 71 +/- 2 (random) +/- 6 (systematic) (Type Ia supernovae), H-o = 71 +/- 3 +/- 7 (Tully-Fisher relation), H-o = 70 +/- 5 +/- 6 (surface brightness fluctuations), H-o = 72 +/- 9 +/- 7 (Type II supernovae), and H-o = 82 +/- 6 +/- 9 (fundamental plane). We combine these results for the different methods with three different weighting schemes, and find good agreement and consistency with H-o = 72 +/- 8 km s(-1) Mpc(-1). Finally, we compare these results with other, global methods for measuring H-o.