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We report on improvements made to the standard NICMOS processing pipeline. The calculation of the uncertainties on the signal accumulation rate has been modified to include the statistical correlations between the consecutive readouts. In order to correct a problem with the existing cosmic ray rejection algorithm, we have developed and implemented a joint fit procedure, where the accumulating signal is fit as linear functions of time with the same rate both before and after the cosmic ray (CR) impact. We also accounted for inter-pixel correlations in the CR-affected region. The new processing is most relevant for deep observations of faint targets, and for PSF fitting, for which unbiased measurements of accurate error estimates are important. We show examples of these improvements for deep NIC2 images of high-redshift supernova from the Supernova Cosmology Project.

This paper describes the design and performance of the OREAD focal-reducing camera, constructed for use at the Cassegrain focus of the Michigan-Dartmouth-MIT Observatory McGraw-Hill 1.3-meter telescope. OREAD is an all-refractive optical system providing a 50-mm collimated beam suitable for commercially available narrow-band filters or grisms. Its collimator and field lens are custom-made to decrease the severe coma which would otherwise be present at the extremities of its 30-arc-min field. When used with a CCD such as the TI 800 X 800, OREAD provides a field of view of 0.1 square degree at 1.̋5 pixel⁻¹. The focal ratio of OREAD of f/1.63 allows sky-limited narrow-band images to be obtained with exposures of only moderate duration. In an Appendix we examine some limitations inherent in coarsely sampled data obtained with CCDs.

This series of review papers is based on the invited talks given at the 184th meeting of the American Astronomical Society for the special topics session, \"Digitizing the Sky.\"

In a series of four papers we investigate the utility of surveys of emission-line galaxies (ELG's) as an efficient means of studying the space distribution of galaxies on scales between 50h$\\sp{-1}$Mpc and 500h$\\sp{-1}$Mpc. We describe the motivation for, and execution of, a narrow-band filter survey for ELG's. The initial survey results are encouraging, with 32 candidate ELG's being detected within a region of 0.25 square degrees. A fast focal-reducing camera, capable of imaging a 20$\\sp\\prime$ x 20$\\sp\\prime$ field onto a TI 800 x 800 CCD on the McGraw-Hill 1.3 meter telescope, was built to improve the efficiency of this survey. The design, construction, and testing of this instrument is discussed. Using newly discovered ELG's from the IRAS Faint Source Survey, we examine their integral and diferential counts in an attempt to detect the galaxy underdensity caused by the Bootes Void. Finding the results ambiguous, we began a redshift survey of IRAS Faint Source Survey galaxies in the Bootes Void. From this survey, we have determined the density contrast of the Bootes Void to be $\\rho\\sb{void\\/}/$ $< \\rho\\ >$ = 0.36 $\\pm$ 0.08. The fact that the Bootes Void continues to have such a large deficit of galaxies when examined with a filled survey, presents problems for the currently popular Cold Dark Matter cosmogonical model, both in its unbiased and biased forms. In addition, the presence of a sizable population of galaxies in the Bootes Void adds additional weight to the argument that galaxies are biased tracers of the mass distribution, and that some types of galaxies (e.g. optically selected galaxies) are more biased than others (e.g. IRAS galaxies).

We describe the target selection and characteristics of the DESI Peculiar Velocity Survey, the largest survey of peculiar velocities (PVs) using both the fundamental plane (FP) and the Tully-Fisher (TF) relationship planned to date. We detail how we identify suitable early-type galaxies (ETGs) for the FP and suitable late-type galaxies (LTGs) for the TF relation using the photometric data provided by the DESI Legacy Imaging Survey DR9. Subsequently, we provide targets for 373 533 ETGs and 118 637 LTGs within the DESI 5-year footprint. We validate these photometric selections using existing morphological classifications. Furthermore, we demonstrate using survey validation data that DESI is able to measure the spectroscopic properties to sufficient precision to obtain PVs for our targets. Based on realistic DESI fiber assignment simulations and spectroscopic success rates, we predict the final DESI PV Survey will obtain \\(\\sim\\)133 000 FP-based and \\(\\sim\\)53 000 TF-based PV measurements over an area of 14 000 \\(\\mathrm{deg^{2}}\\). We forecast the ability of using these data to measure the clustering of galaxy positions and PVs from the combined DESI PV and Bright Galaxy Surveys (BGS), which allows for cancellation of cosmic variance at low redshifts. With these forecasts, we anticipate a \\(4\\%\\) statistical measurement on the growth rate of structure at \\(z<0.15\\). This is over two times better than achievable with redshifts from the BGS alone. The combined DESI PV and BGS will enable the most precise tests to date of the time and scale dependence of large-scale structure growth at \\(z<0.15\\).

The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity Survey aims to measure the peculiar velocities of early and late type galaxies within the DESI footprint using both the Fundamental Plane and optical Tully-Fisher relations. Direct measurements of peculiar velocities can significantly improve constraints on the growth rate of structure, reducing uncertainty by a factor of approximately 2.5 at redshift 0.1 compared to the DESI Bright Galaxy Survey's redshift space distortion measurements alone. We assess the quality of stellar velocity dispersion measurements from DESI spectroscopic data. These measurements, along with photometric data from the Legacy Survey, establish the Fundamental Plane relation and determine distances and peculiar velocities of early-type galaxies. During Survey Validation, we obtain spectra for 6698 unique early-type galaxies, up to a photometric redshift of 0.15. 64\\% of observed galaxies (4267) have relative velocity dispersion errors below 10\\%. This percentage increases to 75\\% if we restrict our sample to galaxies with spectroscopic redshifts below 0.1. We use the measured central velocity dispersion, along with photometry from the DESI Legacy Imaging Surveys, to fit the Fundamental Plane parameters using a 3D Gaussian maximum likelihood algorithm that accounts for measurement uncertainties and selection cuts. In addition, we conduct zero-point calibration using the absolute distance measurements to the Coma cluster, leading to a value of the Hubble constant, \\(H_0 = 76.05 \\pm 0.35\\)(statistical) \\(\\pm 0.49\\)(systematic FP) \\(\\pm 4.86\\)(statistical due to calibration) \\(\\mathrm{km \\ s^{-1} Mpc^{-1}}\\). This \\(H_0\\) value is within \\(2\\sigma\\) of Planck Cosmic Microwave Background results and within \\(1\\sigma\\), of other low redshift distance indicator-based measurements.

The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity Survey aims to measure the peculiar velocities of early and late type galaxies within the DESI footprint using both the Fundamental Plane and Tully-Fisher relations. Direct measurements of peculiar velocities can significantly improve constraints on the growth rate of structure, reducing uncertainty by a factor of approximately 2.5 at redshift 0.1 compared to the DESI Bright Galaxy Survey's redshift space distortion measurements alone. We assess the quality of stellar velocity dispersion measurements from DESI spectroscopic data. These measurements, along with photometric data from the Legacy Survey, establish the Fundamental Plane relation and determine distances and peculiar velocities of early-type galaxies. During Survey Validation, we obtain spectra for 6698 unique early-type galaxies, up to a photometric redshift of 0.15. 64\\% of observed galaxies (4267) have relative velocity dispersion errors below 10\\%. This percentage increases to 75\\% if we restrict our sample to galaxies with spectroscopic redshifts below 0.1. We use the measured central velocity dispersion, along with photometry from the DESI Legacy Imaging Surveys, to fit the Fundamental Plane parameters using a 3D Gaussian maximum likelihood algorithm that accounts for measurement uncertainties and selection cuts. In addition, we conduct zero-point calibration using the absolute distance measurements to the Coma cluster, leading to a value of the Hubble constant, \\(H_0 = 76.05 \\pm 0.35\\)(statistical) \\(\\pm 0.49\\)(systematic FP) \\(\\pm 4.86\\)(statistical due to calibration) \\(\\mathrm{km \\ s^{-1} Mpc^{-1}}\\). This \\(H_0\\) value is within \\(2\\sigma\\) of Planck Cosmic Microwave Background results and within \\(1\\sigma\\), of other low redshift distance indicator-based measurements.

We present the MOST Hosts survey (Multi-Object Spectroscopy of Transient Hosts). The survey is planned to run throughout the five years of operation of the Dark Energy Spectroscopic Instrument (DESI) and will generate a spectroscopic catalog of the hosts of most transients observed to date, in particular all the supernovae observed by most public, untargeted, wide-field, optical surveys (PTF/iPTF, SDSS II, ZTF, DECAT, DESIRT). Scientific questions for which the MOST Hosts survey will be useful include Type Ia supernova cosmology, fundamental plane and peculiar velocity measurements, and the understanding of the correlations between transients and their host galaxy properties. Here, we present the first release of the MOST Hosts survey: 21,931 hosts of 20,235 transients. These numbers represent 36% of the final MOST Hosts sample, consisting of 60,212 potential host galaxies of 38,603 transients (a transient can be assigned multiple potential hosts). Of these galaxies, 40% do not appear in the DESI primary target list and therefore require a specific program like MOST Hosts. Of all the transients in the MOST Hosts list, only 26.7% have existing classifications, and so the survey will provide redshifts (and luminosities) for nearly 30,000 transients. A preliminary Hubble diagram and a transient luminosity-duration diagram are shown as examples of future potential uses of the MOST Hosts survey. The survey will also provide a training sample of spectroscopically observed transients for photometry-only classifiers, as we enter an era when most newly observed transients will lack spectroscopic classification. The MOST Hosts DESI survey data will be released through the Wiserep platform on a rolling cadence and updated to match the DESI releases. Dates of future releases and updates are available through the https://mosthosts.desi.lbl.gov website.

We present confirmation of the cluster MOO J1142+1527, a massive galaxy cluster discovered as part of the Massive and Distant Clusters of WISE Survey. The cluster is confirmed to lie at \\(z=1.19\\), and using the Combined Array for Research in Millimeter-wave Astronomy we robustly detect the Sunyaev-Zel'dovich (SZ) decrement at 13.2\\(\\sigma\\). The SZ data imply a mass of \\(\\mathrm{M}_{200m}=(1.1\\pm0.2)\\times10^{15}\\) \\(\\mathrm{M}_\\odot\\), making MOO J1142+1527 the most massive galaxy cluster known at \\(z>1.15\\) and the second most massive cluster known at \\(z>1\\). For a standard \\(\\Lambda\\)CDM cosmology it is further expected to be one of the \\(\\sim 5\\) most massive clusters expected to exist at \\(z\\ge1.19\\) over the entire sky. Our ongoing Spitzer program targeting \\(\\sim1750\\) additional candidate clusters will identify comparably rich galaxy clusters over the full extragalactic sky.