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(Abridged) Palomar Gattini-IR is a new wide-field, near-infrared robotic time domain survey operating at Palomar Observatory. Using a 30 cm telescope mounted with a H2RG detector, Gattini-IR achieves a field of view of 25 sq. deg. with a pixel scale of 8.7" in J-band. Here, we describe the system design, survey operations, data processing system and on-sky performance of Palomar Gattini-IR. As a part of the nominal survey, Gattini-IR scans $\approx 7500$ square degrees of the sky every night to a median 5$\sigma$ depth of $15.7$ AB mag outside the Galactic plane. The survey covers $\approx 15000$ square degrees of the sky visible from Palomar with a median cadence of 2 days. A real-time data processing system produces stacked science images from dithered raw images taken on sky, together with PSF-fit source catalogs and transient candidates identified from subtractions within a median delay of $\approx 4$ hours from the time of observation. The calibrated data products achieve an astrometric accuracy (RMS) of $\approx 0.7$" with respect to Gaia DR2 for sources with S/N $> 10$, and better than $\approx 0.35$" for sources brighter than $\approx 12$ Vega mag. The photometric accuracy (RMS) achieved in the PSF-fit source catalogs is better than $\approx 3$% for sources brighter than $\approx 12$ Vega mag, as calibrated against the 2MASS catalog. With a field of view $\approx 40\times$ larger than any other existing near infrared imaging instrument, Gattini-IR is probing the reddest and dustiest transients in the local universe such as dust obscured supernovae in nearby galaxies, novae behind large columns of extinction within the galaxy, reddened micro-lensing events in the Galactic plane and variability from cool and dust obscured stars. We present results from transients and variables identified since the start of the commissioning period., Comment: 35 pages, 29 figures. Submitted to PASP

We have mapped the superwind/halo region of the nearby starburst galaxy M82 in the mid-infrared with $Spitzer-IRS$. The spectral regions covered include the H$_2 S(1)-S(3)$, [NeII], [NeIII] emission lines and PAH features. We estimate the total warm H$_2$ mass and the kinetic energy of the outflowing warm molecular gas to be between $M_{warm}\sim5-17\times10^6$ M$_{\odot}$ and $E_{K}\sim6-20\times10^{53}$ erg. Using the ratios of the 6.2, 7.7 and 11.3 micron PAH features in the IRS spectra, we are able to estimate the average size and ionization state of the small grains in the superwind. There are large variations in the PAH flux ratios throughout the outflow. The 11.3/7.7 and the 6.2/7.7 PAH ratios both vary by more than a factor of five across the wind region. The Northern part of the wind has a significant population of PAH's with smaller 6.2/7.7 ratios than either the starburst disk or the Southern wind, indicating that on average, PAH emitters are larger and more ionized. The warm molecular gas to PAH flux ratios (H$_2/PAH$) are enhanced in the outflow by factors of 10-100 as compared to the starburst disk. This enhancement in the H$_2/PAH$ ratio does not seem to follow the ionization of the atomic gas (as measured with the [NeIII]/[NeII] line flux ratio) in the outflow. This suggests that much of the warm H$_2$ in the outflow is excited by shocks. The observed H$_2$ line intensities can be reproduced with low velocity shocks ($v < 40$ km s$^{-1}$) driven into moderately dense molecular gas ($10^2

Large-scale structures (LSS) out to z $< 3.0$ are measured in the Cosmic Evolution Survey (COSMOS) using extremely accurate photometric redshifts (photoz). The Ks-band selected sample (from Ultra-Vista) is comprised of 155,954 galaxies. Two techniques -- adaptive smoothing and Voronoi tessellation -- are used to estimate the environmental densities within 127 redshift slices. Approximately 250 statistically significant overdense structures are identified out to z $= 3.0$ with shapes varying from elongated filamentary structures to more circularly symmetric concentrations. We also compare the densities derived for COSMOS with those based on semi-analytic predictions for a $\Lambda$CDM simulation and find excellent overall agreement between the mean densities as a function of redshift and the range of densities. The galaxy properties (stellar mass, spectral energy distributions (SEDs) and star formation rates (SFRs)) are strongly correlated with environmental density and redshift, particularly at z $< 1.0 - 1.2$. Classifying the spectral type of each galaxy using the rest-frame b-i color (from the photoz SED fitting), we find a strong correlation of early type galaxies (E-Sa) with high density environments, while the degree of environmental segregation varies systematically with redshift out to z $\sim 1.3$. In the highest density regions, 80% of the galaxies are early types at z=0.2 compared to only 20% at z = 1.5. The SFRs and the star formation timescales exhibit clear environmental correlations. At z $> 0.8$, the star formation rate density (SFRD) is uniformly distributed over all environmental density percentiles, while at lower redshifts the dominant contribution is shifted to galaxies in lower density environments., Comment: mp4 versions of some figures available at http://irsa.ipac.caltech.edu/data/COSMOS/ancillary/densities/

We present the Advanced Camera for Surveys General Catalog (ACS-GC), a photometric and morphological database using publicly available data obtained with the Advanced Camera for Surveys (ACS) instrument on the Hubble Space Telescope. The goal of the ACS-GC database is to provide a large statistical sample of galaxies with reliable structural and distance measurements to probe the evolution of galaxies over a wide range of look-back times. The ACS-GC includes approximately 470,000 astronomical sources (stars + galaxies) derived from the AEGIS, COSMOS, GEMS, and GOODS surveys. Galapagos was used to construct photometric (SExtractor) and morphological (Galfit) catalogs. The analysis assumes a single S\'ersic model for each object to derive quantitative structural parameters. We include publicly available redshifts from the DEEP2, COMBO-17, TKRS, PEARS, ACES, CFHTLS,and zCOSMOS surveys to supply redshifts (spectroscopic and photometric) for a considerable fraction (~74%) of the imaging sample. The ACS-GC includes color postage stamps, Galfit residual images, and photometry, structural parameters, and redshifts combined into a single catalog., Comment: 24 pages, 6 Figures, and 5 Tables

With this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the COSMOS field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by AGN-dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy sigma_(Delta z/(1+z_spec)) \sim0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 sq. deg.of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Delta z>0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry H_AB=24 mag. We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together with the number and the depth of the available bands influence the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGN, such as eROSITA at X-ray energies and ASKAP/EMU in the radio band., Comment: ApJ, accepted for publication. Data also available at http://www.ipp.mpg.de/~msalv/PHOTOZ_XCOSMOS

We present three bright z+ dropout candidates selected from deep Near-Infrared (NIR) imaging of the COSMOS 2 square degree field. All three objects match the 0.8-8um colors of other published z>7 candidates but are three magnitudes brighter, facilitating further study. Deep spectroscopy of two of the candidates covering 0.64-1.02um with Keck-DEIMOS and all three covering 0.94-1.10um and 1.52-1.80um with Keck-NIRSPEC detects weak spectral features tentatively identified as Ly-alpha at z=6.95 and z=7.69 in two of the objects. The third object is placed at z~1.6 based on a 24um and weak optical detection. A comparison with the spectral energy distributions of known z<7 galaxies, including objects with strong spectral lines, large extinction, and large systematic uncertainties in the photometry yields no objects with similar colors. However, the lambda>1um properties of all three objects can be matched to optically detected sources with photometric redshifts at z~1.8, so the non-detection in the i+ and z+ bands are the primary factors which favors a z>7 solution. If any of these objects are at z~7 the bright end of the luminosity function is significantly higher at z>7 than suggested by previous studies, but consistent within the statistical uncertainty and the dark matter halo distribution. If these objects are at low redshift, the Lyman-Break selection must be contaminated by a previously unknown population of low redshift objects with very strong breaks in their broad band spectral energy distributions and blue NIR colors. The implications of this result on luminosity function evolution at high redshift is discussed. We show that the primary limitation of z>7 galaxy searches with broad filters is the depth of the available optical data., Comment: 15 Pages, 15 figures, accepted to ApJ

The Chandra COSMOS Survey (C-COSMOS) is a large, 1.8 Ms, Chandra} program that has imaged the central 0.5 sq.deg of the COSMOS field (centered at 10h, +02deg) with an effective exposure of ~160ksec, and an outer 0.4sq.deg. area with an effective exposure of ~80ksec. The limiting source detection depths are 1.9e-16 erg cm(-2) s(-1) in the Soft (0.5-2 keV) band, 7.3e(-16) erg cm^-2 s^-1 in the Hard (2-10 keV) band, and 5.7e(-16) erg cm(-2) s(-1) in the Full (0.5-10 keV) band. Here we describe the strategy, design and execution of the C-COSMOS survey, and present the catalog of 1761 point sources detected at a probability of being spurious of <2e(-5) (1655 in the Full, 1340 in the Soft, and 1017 in the Hard bands). By using a grid of 36 heavily (~50%) overlapping pointing positions with the ACIS-I imager, a remarkably uniform (to 12%) exposure across the inner 0.5 sq.deg field was obtained, leading to a sharply defined lower flux limit. The widely different PSFs obtained in each exposure at each point in the field required a novel source detection method, because of the overlapping tiling strategy, which is described in a companion paper. (Puccetti et al. Paper II). This method produced reliable sources down to a 7-12 counts, as verified by the resulting logN-logS curve, with sub-arcsecond positions, enabling optical and infrared identifications of virtually all sources, as reported in a second companion paper (Civano et al. Paper III). The full catalog is described here in detail, and is available on-line., Comment: Revised to omit egregious bold facing and fix missing ',' in author list

We present Spitzer 70 and 160 micron observations of the COSMOS Spitzer survey (S-COSMOS). The data processing techniques are discussed for the publicly released products consisting of images and source catalogs. We present accurate 70 and 160 micron source counts of the COSMOS field and find reasonable agreement with measurements in other fields and with model predictions. The previously reported counts for GOODS-North and the extragalactic First Look Survey are updated with the latest calibration, and counts are measured based on the large area SWIRE survey to constrain the bright source counts. We measure an extragalactic confusion noise level of sigma_c = 9.4+/-3.3 mJy (q=5) for the MIPS 160-micron band based on the deep S-COSMOS data and report an updated confusion noise level of sigma_c = 0.35+/-0.15 mJy (q=5) for the MIPS 70-micron band., Comment: Accepted AJ, 15 Aug. 2009. Data available at http://spider.ipac.caltech.edu/staff/frayer/mycosmos/ until released by IRSA

The COSMOS survey is a multiwavelength survey aimed to study the evolution of galaxies, AGN and the large scale structure. The XMM-COSMOS is a deep X-ray survey over the full 2 deg2 of the COSMOS area. It consists of 55 XMM-Newton pointings for a total exposure of ~1.5 Ms with an average vignetting corrected depth of 40 ks across the field of view and a sky coverage of 2.13 deg2. We present the catalogue of point-like X-ray sources detected with the EPIC CCD cameras, the logN-logS relations and the X-ray colour-colour diagrams. The analysis was performed in the 0.5-2 keV, 2-10 keV and 5-10 keV energy bands. The completeness of the catalogue as well as logN-logS have been calibrated using Monte Carlo simulations. The catalogs contains a total of 1887 unique sources detected in at least one band. The survey, that shows unprecedented homogeneity, has a flux limit of ~1.7x10-15 erg cm-2 s-1, ~9.3x10-15 erg cm-2 s-1 and ~1.3x10-14 erg cm-2 s-1 over 90% of the area (1.92 deg2) in the 0.5-2 keV, 2-10 keV and 5-10 keV energy band, respectively. Thanks to the rather homogeneous exposure over a large area, the derived logN-logS relations are very well determined over the flux range sampled by XMM-COSMOS. These relations have been compared with XRB synthesis models, which reproduce the observations with an agreement of ~10% in the 5-10 keV and 2-10 keV band, while in the 0.5-2 keV band the agreement is of the order of ~20%. The hard X-ray colors confirmed that the majority of the extragalactic sources, in a bright subsample, are actually Type I or Type II AGN. About 20% of the sources have X-ray luminosity typical of AGN (L_X >1042 erg/s) although they do not show any clear signature of nuclear activity in the optical spectrum., Comment: Astronomy and Astrophysics, accepted, language edited. The XMM-COSMOS source catalog and science data products are available at http://irsa.ipac.caltech.edu/data/COSMOS/ by A&A 16 pages, 12 Figures, Color printing suggested

We present photometric redshifts and spectral energy distribution (SED) classifications for a sample of 1542 optically identified sources detected with XMM in the COSMOS field. Our template fitting classifies 46 sources as stars and 464 as non-active galaxies, while the remaining 1032 require templates with an AGN contribution. High accuracy in the derived photometric redshifts was accomplished as the result of 1) photometry in up to 30 bands with high significance detections, 2) a new set of SED templates including 18 hybrids covering the far-UV to mid-infrared, which have been constructed by the combination of AGN and non-active galaxies templates, and 3) multi-epoch observations that have been used to correct for variability (most important for type 1 AGN). The reliability of the photometric redshifts is evaluated using the sub-sample of 442 sources with measured spectroscopic redshifts. We achieved an accuracy of $\sigma_{\Delta z/(1+z_{spec})} = 0.014$ for i$_{AB}^*<$22.5 ($\sigma_{\Delta z/(1+z_{spec})} \sim0.015$ for i$_{AB}^*<$24.5). The high accuracies were accomplished for both type 2 (where the SED is often dominated by the host galaxy) and type 1 AGN and QSOs out to $z=4.5$. The number of outliers is a large improvement over previous photometric redshift estimates for X-ray selected sources (4.0% and 4.8% outliers for i$_{AB}^*<$22.5 and i$_{AB}^*<$24.5, respectively). We show that the intermediate band photometry is vital to achieving accurate photometric redshifts for AGN, whereas the broad SED coverage provided by mid infrared (Spitzer/IRAC) bands is important to reduce the number of outliers for normal galaxies., Comment: Accepted for publication in ApJ

To derive a new H$\alpha$ luminosity function and to understand the clustering properties of star-forming galaxies at $z \approx 0.24$, we have made a narrow-band imaging survey for H$\alpha$ emitting galaxies in the HST COSMOS 2 square degree field. We used the narrow-band filter NB816 ($\lambda_c = 8150$ \AA, $\Delta \lambda = 120$ \AA) and sampled H$\alpha$ emitters with $EW_{\rm obs}(\rm H\alpha + [N\textsc{ii}]) > 12$ \AA in a redshift range between $z=0.233$ and $z=0.251$ corresponding to a depth of 70 Mpc. We obtained 980 H$\alpha$ emitting galaxies in a sky area of 5540 arcmin$^2$, corresponding to a survey volume of $3.1 \times 10^4 {\rm Mpc^3}$. We derive a H$\alpha$ luminosity function with a best-fit Schechter function parameter set of $\alpha = -1.35^{+0.11}_{-0.13}$, $\log\phi_* = -2.65^{+0.27}_{-0.38}$, and $\log L_* ({\rm erg s^{-1}}) = 41.94^{+0.38}_{-0.23}$. The H$\alpha$ luminosity density is $2.7^{+0.7}_{-0.6} \times 10^{39}$ ergs s$^{-1}$ Mpc$^{-3}$. After subtracting the AGN contribution (15 %) to the H$\alpha$ luminosity density, the star formation rate density is evaluated as $1.8^{+0.7}_{-0.4} \times 10^{-2}$ $M_{\sun}$ yr$^{-1}$ Mpc$^{-3}$. The angular two-point correlation function of H$\alpha$ emitting galaxies of $\log L({\rm H\alpha}) > 39.8$ is well fit by a power law form of $w(\theta) = 0.013^{+0.002}_{-0.001} \theta^{-0.88 \pm 0.03}$, corresponding to the correlation function of $\xi(r) = (r/1.9{\rm Mpc})^{-1.88}$. We also find that the H$\alpha$ emitters with higher H$\alpha$ luminosity are more strongly clustered than those with lower luminosity., Comment: 13 pages, 9 fifgure, to apper in ApJS

We present imaging data and photometry for the COSMOS survey in 15 photometric bands between 0.3um and 2.4um. These include data taken on the Subaru 8.3m telescope, the KPNO and CTIO 4m telescopes, and the CFHT 3.6m telescope. Special techniques are used to ensure that the relative photometric calibration is better than 1% across the field of view. The absolute photometric accuracy from standard star measurements is found to be 6%. The absolute calibration is corrected using galaxy spectra, providing colors accurate to 2% or better. Stellar and galaxy colors and counts agree well with the expected values. Finally, as the first step in the scientific analysis of these data we construct panchromatic number counts which confirm that both the geometry of the universe and the galaxy population are evolving., Comment: 19 pages, 13 figures, 14 tables, Accepted to ApJS for COSMOS speciall issue

We describe the details of the Hubble Space Telescope (HST) Advanced Camera for Surveys / Wide Field Channel (ACS/WFC) observations of the COSMOS field, including the data calibration and processing procedures. We obtained a total of 583 orbits of HST ACS/WFC imaging in the F814W filter, covering a field that is 1.64 square degrees in area, the largest contiguous field ever imaged with HST. The median exposure depth across the field is 2028 seconds (one HST orbit), achieving a limiting point-source depth AB(F814W) = 27.2 (5 sigma). We also present details about the astrometric image registration, distortion removal and image combination using MultiDrizzle, as well as motivating the choice of our final pixel scale (30 milliarcseconds per pixel), based on the requirements for weak lensing science. The final set of images are publicly available through the archive sites at IPAC and STScI, along with further documentation on how they were produced., Comment: Accepted for ApJ COSMOS Special Issue, 17 pages, 4 figures, aastex. A version with higher resolution figures is available at: http://www.stsci.edu/~koekemoe/

We have carried out a wide-field imaging survey for [OII]3727 emitting galaxies at z~1.2 in the HST COSMOS 2 square degree field using the Suprime-Cam on the Subaru Telescope. The survey covers a sky area of 6700 arcmin^2 in the COSMOS field, and a redshift range between 1.17 and 1.20 (Delta_z = 0.03), corresponding to a survey volume of 5.56*10^5 Mpc^3. We obtain a sample of 3176 [OII] emitting galaxies with observed emission-line equivalent widths greater than 26 AA. Since our survey tends to sample brighter [OII]3727 emitting galaxies, we also analyze a sample of fainter [OII]3727 emitting galaxies found in the Subaru Deep Field (SDF). We find an extinction-corrected [OII] luminosity density of 10^{40.35^+0.08_-0.06} ergs s^-1 Mpc-3, corresponding to star formation rate density of 0.32^+0.06_-0.04 M_sun yr-1 Mpc^-3 in the COSMOS field at z~1.2. This is the largest survey for [OII]3727 emitters beyond z=1 currently available., Comment: 33 pages, 9 figures. to appear in the ApJ Supplement COSMOS Special Issue

We present a three dimensional cosmic shear analysis of the Hubble Space Telescope COSMOS survey, the largest ever optical imaging program performed in space. We have measured the shapes of galaxies for the tell-tale distortions caused by weak gravitational lensing, and traced the growth of that signal as a function of redshift. Using both 2D and 3D analyses, we measure cosmological parameters Omega_m, the density of matter in the universe, and sigma_8, the normalization of the matter power spectrum. The introduction of redshift information tightens the constraints by a factor of three, and also reduces the relative sampling (or "cosmic") variance compared to recent surveys that may be larger but are only two dimensional. From the 3D analysis, we find sigma_8*(Omega_m/0.3)^0.44=0.866+^0.085_-0.068 at 68% confidence limits, including both statistical and potential systematic sources of error in the total budget. Indeed, the absolute calibration of shear measurement methods is now the dominant source of uncertainty. Assuming instead a baseline cosmology to fix the geometry of the universe, we have measured the growth of structure on both linear and non-linear physical scales. Our results thus demonstrate a proof of concept for tomographic analysis techniques that have been proposed for future weak lensing surveys by a dedicated wide-field telescope in space., Comment: 21 pages, 15 figures. Accepted for the COSMOS ApJ Suppl. special issue

The Spitzer-COSMOS survey (S-COSMOS) is a Legacy program (Cycles 2+3) designed to carry out a uniform deep survey of the full 2 sq deg COSMOS field in all seven Spitzer bands (3.6, 4.5, 5.6, 8.0, 24.0, 70.0, 160.0 u). This paper describes the survey parameters, mapping strategy, data reduction procedures, achieved sensitivities to date, and the complete data set for future reference. We show that the observed infrared backgrounds in the S-COSMOS field are within 10% of the predicted background levels. The fluctuations in the background at 24u have been measured and do not show any significant contribution from cirrus, as expected. In addition, we report on the number of asteroid detections in the low galactic latitude COSMOS field. We use the Cycle 2 S-COSMOS data to determine preliminary number counts, and compare our results with those from previous Spitzer Legacy surveys (e.g. SWIRE, GOODS). The results from this "first analysis" confirm that the S-COSMOS survey will have sufficient sensitivity with IRAC to detect ~ L* disks and spheroids out to z ~ 3, and with MIPS to detect ultraluminous starbursts and AGN out to z ~3 at 24u and out to z ~1.5-2 at 70u and 160u., Comment: 21 pages including 4 tables and 9 figures. Accepted for Publication on ApJS COSMOS special Issue

We present the first identification of large-scale structures (LSS) at z $< 1.1$ in the Cosmic Evolution Survey (COSMOS). The structures are identified from adaptive smoothing of galaxy counts in the pseudo-3d space ($\alpha,\delta$,z) using the COSMOS photometric redshift catalog. The technique is tested on a simulation including galaxies distributed in model clusters and a field galaxy population -- recovering structures on all scales from 1 to 20\arcmin without {\it a priori} assumptions for the structure size or density profile. Our procedure makes {\bf no} {\it a priori} selection on galaxy spectral energy distribution (SED, for example the Red Sequence), enabling an unbiased investigation of environmental effects on galaxy evolution. The COSMOS photometric redshift catalog yields a sample of $1.5\times10^5$ galaxies with redshift accuracy, $\Delta z_{FWHM}/(1+z) \leq 0.1$ at z $< 1.1$ down to I$_{AB} \leq 25$ mag. Using this sample of galaxies, we identify 42 large-scale structures and clusters. abstract truncated for astroph 25 line limit -- see preprint, Comment: 72 pages with 29 pages of figures, for cosmos apj suppl special issue

We present a detailed spectral analysis of point-like X-ray sources in the XMM-COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with either no absorption (76%) or a significant intrinsic, absorbing column (20%).As expected, the distribution of intrinsic absorbing column densities is markedly different between AGN with or without broad optical emission lines. We find within our sample four Type-2 QSOs candidates (L_X > 10^44 erg/s, N_H > 10^22 cm^-2), with a spectral energy distribution well reproduced by a composite Seyfert-2 spectrum, that demonstrates the strength of the wide field XMM/COSMOS survey to detect these rare and underrepresented sources., Comment: 16 pages, ApJS COSMOS Special Issue, 2007 in press. The full-resolution version is available at http://www.mpe.mpg.de/XMMCosmos/PAPERS/mainieri_cosmos.ps.gz

We measure photometric redshifts and spectral types for galaxies in the COSMOS survey. We use template fitting technique combined with luminosity function priors and with the option to simultaneously estimate dust extinction (i.e. E(B-V)) for each galaxy.Our estimated redshifts are accurate to i<25 and z~1.2. Using simulations with sampling and noise characteristics similar to those in COSMOS, the accuracy and reliability is estimated for the photometric redshifts as a function of the magnitude limits of the sample, S/N ratios and the number of bands used. From the simulations we find that the ratio of derived 95% confidence interval in the redshift probability distribution to the estimated photometric redshift (D95) can be used to identify and exclude the catastrophic failures in the photometric redshift estimates. We compare the derived redshifts with high-reliability spectroscopic redshifts for a sample of 868 normal galaxies with z < 1.2 from zCOSMOS. Considering different scenarios, depending on using prior, no prior and/or extinction, we compare the photometric and spectroscopic redshifts for this sample. This corresponds to an rms scatter of 0.031, with a small number of outliers (<2.5%). We also find good agreement (rms=0.10) between photometric and spectroscopic redshifts for Type II AGNs. We compare results from our photometric redshift procedure with three other independent codes and find them in excellent agreement. We show preliminary results, based on photometric redshifts for the entire COSMOS sample (to i < 25 mag.)., Comment: 38 pages; 14 Figures; 7 Tables. Accepted for Publication in ApJS. COSMOS Special Issue

The Cosmic Evolution Survey (COSMOS) is designed to probe the correlated evolution of galaxies, star formation, active galactic nuclei (AGN) and dark matter (DM) with large-scale structure (LSS) over the redshift range z $> 0.5 $ to 6. The survey includes multi-wavelength imaging and spectroscopy from X-ray to radio wavelengths covering a 2 $\sq$\deg area, including HST imaging. Given the very high sensitivity and resolution of these datasets, COSMOS also provides unprecedented samples of objects at high redshift with greatly reduced cosmic variance, compared to earlier surveys. Here we provide a brief overview of the survey strategy, the characteristics of the major COSMOS datasets, and summarize the science goals., Comment: 22 pages, 3 figures

The Cosmic Evolution Survey (COSMOS) was initiated with an extensive allocation (590 orbits in Cycles 12-13) using the Hubble Space Telescope (HST) for high resolution imaging. Here we review the characteristics of the HST imaging with the Advanced Camera for Surveys (ACS) and parallel observations with NICMOS and WFPC2. A square field (1.8$\sq$\deg) has been imaged with single-orbit ACS I-F814W exposures with 50% completeness for sources 0.5\arcsec in diameter at I$_{AB} $ = 26.0 mag. The ACS imaging is a key part of the COSMOS survey, providing very high sensitivity and high resolution (0.09\arcsec FWHM, 0.05\arcsec pixels) imaging and detecting 1.2 million objects to a limiting magnitude of 26.5 (AB). These images yield resolved morphologies for several hundred thousand galaxies. The small HST PSF also provides greatly enhanced sensitivity for weak lensing investigations of the dark matter distribution., Comment: 21 pages, 6 figures -- to appear in COSMOS ApJ Suppl. special issue

We present deep optical imaging observations of 2 square degree area, covered by the Cosmic Evolution Survey (COSMOS), made by the prime-focus Camera (Supreme-Cam) on the 8.2m Subaru Telescope. Observations were done in six broad-band [B (4459.7 AA), g' (4723.1 AA), V (5483.8 AA), r' (6213.0 AA), i' (7640.8 AA), z' (8855.0 AA)], and one narrow-band (NB816) filters. A total of 10^6 galaxies were detected to i'~26.5 mag. These data, combined with observations at u* and K-band are used to construct the photometric catalogs for the COSMOS and to measure their photometric redshifts, multi-band spectral energy distributions, stellar masses and identification of high redshift candidates. This catalog provides multi-waveband data for scientific analysis of the COSMOS survey., Comment: 46 pages, 32 figures, accepted for the COSMOS special issue of ApJS

We report the results from a pilot study of 10 nearby starburst and active galaxies conducted with the Taurus Tunable Filter (TTF) on the Anglo-Australian and William Herschel Telescopes. The main purpose of this imaging survey is to search for warm emission-line gas on the outskirts (galactocentric distances R > 10 kpc) of galaxies to provide direct constraints on the size and geometry of the ``zone of influence'' of these galaxies on their environment. Gaseous complexes or filaments larger than ~ 20 kpc are discovered or confirmed in six of the galaxies in the sample (NGC 1068, NGC 1482, NGC 4388, NGC 6240, NGC 7213, and MR 2251-178). Slightly smaller structures are seen for the first time in the ionization cones and galactic winds of NGC 1365, NGC 1705, Circinus galaxy, and ESO484-G036. The TTF data are combined with new optical long-slit spectra as well as published and archived radio and X-ray maps to constrain the origin and source of ionization of these filaments. A broad range of phenomena is observed, including large-scale ionization cones and galactic winds, tidal interaction, and ram-pressure stripping by an intracluster medium. The source of ionization in this gas ranges from shock ionization to photoionization by the central AGN or in-situ hot young stars. The sample is too small to draw statistically meaningful conclusions about the extent and properties of the warm ionized medium on large scale and its relevance to galaxy formation and evolution. The next generation of tunable filters on large telescopes promises to improve the sensitivity to faint emission-line fluxes at least tenfold and allow systematic surveys of a large sample of emission-line galaxies., Comment: 17 pages + 20 gif figures (high-resolution color version of these gif figures will be available with the electronic version of the published paper). Accepted for publication in the Astronomical Journal, November 2003 issue

The past five years have seen a rapid rise in the use of tunable filters in many diverse fields of astronomy, through Taurus Tunable Filter (TTF) instruments at the Anglo-Australian and William Herschel Telescopes. Over this time we have continually refined aspects of operation and developed a collection of special techniques to handle the data produced by these novel imaging instruments. In this paper, we review calibration procedures and summarize the theoretical basis for Fabry-Perot photometry that is central to effective tunable imaging. Specific mention is made of object detection and classification from deep narrowband surveys containing several hundred objects per field. We also discuss methods for recognizing and dealing with artefacts (scattered light, atmospheric effects, etc.) which can seriously compromise the photometric integrity of the data if left untreated. Attention is paid to the different families of ghost reflections encountered, and strategies to minimise their presence. In our closing remarks, future directions for tunable imaging are outlined and contrasted with the Fabry-Perot technology employed in the current generation of tunable imagers., Comment: 19 pages, 17 figures, to appear in MNRAS. Obtain higher quality figures at http://www.sc.eso.org/~hjones/WWWpubl/FIGSdetectmeas/ or http://www.aao.gov.au/ttf/WWWpubl/FIGSdetectmeas/

We report sub arc-second resolution X-ray imaging-spectroscopy of the archetypal type 2 Seyfert galaxy NGC 1068 with the Chandra X-ray Observatory. The observations reveal the detailed structure and spectra of the 13 kpc-extent nebulosity previously imaged at lower resolution with ROSAT. The Chandra image shows a bright, compact source coincident with the brightest radio and optical emission; this source is extended by \simeq 1.5 arcsec (165 pc) in the same direction as the nuclear optical line and radio continuum emission. Bright X-ray emission extends \simeq 5 arcsec (550 pc) to the NE and coincides with the NE radio lobe and gas in the narrow line region. The large-scale emission shows trailing spiral arms and other structures. Numerous point sources associated with NGC 1068 are seen. There is a very strong correlation between the X-ray emission and the high excitation ionized gas seen in HST and ground-based [O III] \lambda 5007 images. The X-rays to the NE of the nucleus are absorbed by only the Galactic column density and thus originate from the near side of the disk of NGC 1068. In contrast the X-rays to the SW are more highly absorbed and must come from gas in the disk or on the far side of it. This geometry is similar to that inferred for the narrow line region and radio lobes. (Abstract truncated)., Comment: To be published in the Astrophysical Journal, July 20 2001 issue; 49 pages, 19 figures

We describe observations of the two nearest, powerful radio galaxies with the Chandra X-ray Observatory: Cygnus A (z = 0.0562) and Pictor A (z = 0.035). Since the early results from these observations are published elsewhere (Wilson, Young & Shopbell 2000, 2001), we here confine ourselves to a summary of the main conclusions and a few remarks about other aspects of the results on Cygnus A, which will be amplified in a future paper., Comment: To be published in the Proceedings of the Oxford Conference ``Particles and Fields in Radio Galaxies'', Eds R. A. Laing and K. M. Blundell, ASP Conference Series (2001); 7 pages, 7 figures

Recent results from a multiwavelength survey of spatially resolved outflows in nearby active galaxies are presented. Optical Fabry-Perot and long-slit spectroscopic data are combined with VLA and ROSAT images, when available, to probe the warm, relativistic and hot gas components involved in the outflow. The emphasis is put on objects which harbor wide-angle galactic-scale outflows but also show evidence at radio or optical wavelengths for collimated jet-like phenomena (e.g., Circinus, NGC 4388, and to a lesser extent NGC 2992). Our results are compared with the predictions from published jet-driven thermal wind models., Comment: Invited talk presented at the conference on "Emission Lines from Jet Flows", held on Isla Mujeres, Mexico, November 2000

We report on a detailed kinematic study of the galactic-scale outflow in the Seyfert galaxy NGC 2992. The TAURUS-2 Imaging Fabry-Perot Interferometer was used on the Anglo-Australian 3.9-m telescope to derive the two-dimensional velocity field of the Halpha-emitting gas over the central arcminute of NGC 2992. The complete two-dimensional coverage of the data combined with simple kinematic models of rotating axisymmetric disks allows us to differentiate the outflowing material from the line-emitting material associated with the galactic disk. The kinematics of the disk component out to R = 3.0 kpc are well modeled by pure circular rotation. The outflow component is distributed into two wide cones with opening angle of 125 -- 135 degrees and extending 2.8 kpc (18") on both sides of the nucleus at nearly right angles to the disk kinematic major axis. The outflow on the SE side of the nucleus is made of two distinct kinematic components interpreted as the front and back walls of a cone. The azimuthal velocity gradient in the back-wall component reflects residual rotational motion which indicates either that the outflowing material was lifted from the disk or that the underlying galactic disk is contributing slightly to this component. A single outflow component is detected in the NW cone. The most likely energy source for this outflow is a hot bipolar thermal wind powered on sub-kpc scale by the AGN and diverted along the galaxy minor axis by the pressure gradient of the ISM in the host galaxy. The data are not consistent with a starburst-driven wind or a collimated outflow powered by radio jets. (abridged), Comment: 28 pages including 8 figures (2 ps, 6 jpeg), Latex w/ aaspp4.sty

We report X-ray observations of the powerful radio galaxy Cygnus A with the Chandra X-ray Observatory. This letter focuses on the radio hot spots, all four of which are detected in X-rays with a very similar morphology to their radio structure. X-ray spectra have been obtained for the two brighter hot spots (A and D). Both are well described by a power law with photon index \Gamma = 1.8 \pm 0.2 absorbed by the Galactic column in the direction of Cygnus A. Thermal X-ray models require too high gas densities and may be ruled out. The images and spectra strongly support synchrotron self-Compton models of the X-ray emission, as proposed by Harris, Carilli & Perley on the basis of ROSAT imaging observations. Such models indicate that the magnetic field in each of the brighter hot spots is 1.5 \times 10^-4 gauss, with an uncertainty of a few tens of percent. This value is close to the equipartition field strengths assuming no protons are present. The possibility that the X-rays are synchrotron radiation is briefly discussed, but not favored. We speculate that production of the \gamma \sim 10^7 electrons necessary for X-ray synchrotron radiation from hot spots is inhibited when the external gas density is high, as is the case when the radio galaxy is within a cooling flow., Comment: 14 pages, 5 figues (3 JPEG, 2 Postscript), accepted for publication in the Astrophysical Journal (Letters)

We present the detection of He II sources in the Im galaxy NGC 1569 from HST WFPC2 imagery. Out of the fifteen detections, seven were Wolf-Rayet stars, five were stellar clusters with associated He II emission, and three were sources of unknown origin. The detected Wolf-Rayet stars' colors and magnitudes are similar to Large Magellanic Cloud late-type WN stars. The physical origin of the other He II sources are discussed. We conclude that the equivalent of 51+/-19 WNL stars have been detected in NGC 1569, and we have estimated the total Wolf-Rayet population in NGC 1569 as 78+/-51. These numbers are compared with the Wolf-Rayet stellar populations in the SMC, LMC, Milky Way, and other starburst galaxies relative to their luminosities, dynamical masses, and ionized gas masses. Previous to this study, Wolf-Rayet stars in NGC 1569 were not detected using ground-based imagery, but were only indicated through longslit spectroscopy. This is the first time the exact locations of the Wolf-Rayet stars in this nearby, well-studied, "post-starburst" galaxy have been determined., Comment: 36 pages, 9 figures, & 4 tables

We report X-ray observations of the nearby, powerful radio galaxy Pictor A with the Chandra Observatory and optical and near uv observations of its western radio hot spot with the Hubble Space Telescope. X-ray emission is detected from the nucleus, a 1.9 arcmin (110 kpc) long jet to the west of the nucleus, the western radio hot spot some 4.2 arcmin (240 kpc) from the nucleus, and the eastern radio lobe. The morphology of the western hot spot is remarkably similar to that seen at radio and optical wavelengths, where the emission is known to be synchrotron radiation. The X-ray spectrum of the hot spot is well described by an absorbed power law with photon index \Gamma = 2.07 (+/- 0.11). The X-ray jet coincides with a weak radio jet and is laterally extended by \simeq 2.0 arcsec (1.9 kpc). The observed jet is up to \simeq 15 times brighter in X-rays than any counter jet, a difference ascribed to relativistic boosting as the western radio lobe is probably the closer. The jet's spectrum is well modelled by an absorbed power law with \Gamma = 1.94 (+0.43/-0.49) and poorly fitted by a Raymond-Smith thermal plasma model. (Abstract truncated)., Comment: 42 pages, 9 figures (3 JPEG, 6 Postscript), accepted for publication in the Astrophysical Journal, Vol 546, Jan 10 2001 issue. Section 4.3.2 revised October 12

We present an HST imaging study of the nearby (4 Mpc distant) Circinus galaxy, which contains the nearest type 2 Seyfert nucleus and prominent circumnuclear star formation. Images have been obtained in the [OIII]$\lambda$5007, H$\alpha$ and H$_2$ v=1--0 S(1) emission lines, and in the green (5470 \AA), red (8140 \AA) and near infrared (2.04 and 2.15 $\mu$m) continua. An image in the [Fe II] $\lambda$1.644 $\mu$m line has been taken with a ground-based telescope. The [OIII] and H$\alpha$ images reveal the detailed structure of the complex of streamers and knots of high-excitation gas, which extends out of the galaxy disk. The morphology some 250 pc from the nucleus strongly suggests that the high-excitation gas is concentrated on the surface of a hollow cone with apex close to the nucleus. Such a structure may result through entrainment of dense gas from a circumnuclear torus in the galaxy disk by a low density, outflowing wind or jet. Within 40 pc of the nucleus, the high-excitation gas takes the form of a striking, filled V-shaped structure extending in the same direction as the larger scale high-excitation emission. This `V' can be described as an ionization cone, though a matter-bounded structure is also possible. The implied collimation of the ionizing photons or gaseous outflow must occur within 2 pc of the apex of the cone, presumed to be the location of the nucleus. The H$\alpha$ image shows a complex structure of HII regions, including the well known starburst ring of radius 150 - 270 pc. In addition, there is a more compact (40 pc radius), elliptical ring of HII regions around the `ionization cone'. We argue that this latter ring, which we call the nuclear ring, is intrinsically circular and located in the plane of the galaxy disk. Abstract truncated., Comment: With 12 figures, to be published in the Astronomical Journal, September 2000 issue

A redshift survey has been carried out in the region of the Hubble Deep Field North using the Low Resolution Imaging Spectrograph at the Keck Observatory. The resulting redshift catalog, which contains 671 entries, is a compendium of our own data together with published LRIS/Keck data. It is more than 92% complete for objects, irrespective of morphology, to $R = 24$ mag in the HDF itself and to $R = 23$ mag in the Flanking Fields within a diameter of 8 arcmin centered on the HDF, an unusually high completion for a magnitude limited survey performed with a large telescope. A median redshift $z = 1.0$ is reached at $R \sim 23.8$. Strong peaks in the redshift distribution, which arise when a group or poor cluster of galaxies intersect the area surveyed, can be identified to $z \sim 1.2$ in this dataset. More than 68% of the galaxies are members of these redshift peaks. In a few cases, closely spaced peaks in $z$ can be resolved into separate groups of galaxies that can be distinguished in both velocity and location on the sky. The radial separation of these peaks in the pencil-beam survey is consistent with a characteristic length scale for the their separation of $\approx$70 Mpc in our adopted cosmology ($h = 0.6, \Omega_M = 0.3$, $\Lambda = 0$). Strong galaxy clustering is in evidence at all epochs back to $z \le 1.1$. (abstract abridged), Comment: Accepted to the ApJ. This version contains all the figures and tables. 2 minor typos in table 2b corrected

We report the results of deep H-alpha imaging of the ionized gas surrounding the low-redshift (z=0.0638) quasar MR 2251-178 using the TAURUS Tunable Filter (TTF) on the Anglo-Australian Telescope. Our observations reach a 2-sigma detection level of ~5 x 10^-18 erg s^-1 cm^-2 arcsec^-2, more than an order of magnitude deeper than conventional narrowband images previously published on this object. Our data reveal a spiral complex that extends more or less symmetrically over ~200 kpc, making it the largest known quasar nebula. The total mass of ionized gas is 6 x 10^10 solar masses (upper limit), a large fraction of which is in a very faint, diffuse component. The large and symmetric extent of the gaseous envelope favors a model in which the filamentary and diffuse emission arises from a large cloud complex, photoionized by the bright quasar. A crude kinematic analysis reveals relatively smooth rotation, suggesting that the envelope did not originate with a cooling flow, a past merger event, or an interaction with the nearby galaxy G1., Comment: 10 pages, 1 figure, accepted by ApJ (Letters); also available at http://www.astro.umd.edu/~pls/papers/apj/mr2251-178/

The results of a spectroscopic investigation of a complete sample of objects with $K_s<20$ mag in a 2 by 7.3 arcmin field at J005325+1234 are reported. Redshifts were successfully obtained for 163 of the 195 objects in the sample; these redshifts lie in the range [0.173, 1.44] and have a median of 0.58 (excluding 24 Galactic stars). The redshift identifications are believed to be almost complete for $z < 0.8$. Approximately half of the galaxies lie in five narrow redshift features with local velocity dispersions of $ \sim 300 km/s$. These narrow redshift ``peaks'' are primarily populated both by absorption--line galaxies and the most luminous galaxies in the sample, although the incidence of emission lines in the luminous galaxies increases with redshift. The estimated dynamical masses of these redshift peaks, and the sky distribution of the galaxies within them, appear similar to groups or poor clusters of galaxies in the local universe at various stages of virialization. Some groups of galaxies therefore form at epochs $z > 1.5$, and the galaxies in such groups appear to be coeval and to show little sign of ongoing star formation. The galaxies outside the redshift peaks are also clustered, albeit more weakly, are less luminous and more frequently exhibit strong emission lines. These ``isolated'' galaxies therefore appear, on average, to form stars at later epochs than the strongly clustered galaxies. The galaxy SEDs derived from our $UBVRIK$ photometry are also very closely correlated with the galaxy spectral types and luminosities. These results have strong implications for the analysis of redshift surveys at intermediate redshift., Comment: 42 pages, Latex, 11 figures, accepted for publication in the Astrophysical Journal (abstract exceeds allocated space and was truncated)

We present the techniques used to determine redshifts and to characterize the spectra of objects in the Caltech Faint Galaxy Redshift Survey in terms of spectral classes and redshift quality classes. These are then applied to spectra from an investigation of a complete sample of objects with $K_s<20$ mag in a 2 by 7.3 arcmin^2 field at J005325+1234. Redshifts were successfully obtained for 163 of the 195 objects in the sample; these redshifts lie in the range [0.173, 1.44] and have a median of 0.58 (excluding 24 Galactic stars). The sample includes two broad lined AGNs and one QSO., Comment: 20 pages, Latex, 3 figures, accepted for publication in the ApJ Supplements

We discuss the very red objects found in the first field of the Caltech Faint Galaxy Redshift Survey, for which the observations and analysis are now complete. In this field, which is 15 arcmin$^2$ and at J005325+1234 there are 195 objects with $K_s < 20$ mag, of which 84% have redshifts. The sample includes 24 spectroscopically confirmed Galactic stars, 136 galaxies, three AGNs, and 32 objects without redshifts. About 10% of the sample has $(R-K) \ge 5$ mag. Four of these objects have redshifts, with $0.78 \le z \le 1.23$. Three of these are based on absorption features in the mid-UV, while the lowest redshift object shows the standard features near 4000\AA. Many of the objects still without redshifts have been observed spectroscopically, and no emission lines were seen in their spectra. We believe they are galaxies with $z \sim 1 - 1.5$ that are red due to their age and stellar content and not to some large amount of internal reddening from dust. Among the many other results from this survey of interest here is a determination of the median extinction in the mid-UV for objects with strong emission line spectra at $z \sim 1 - 1.3$. The result is extinction by a factor of $\sim$2 at 2400\AA., Comment: 6 pages, Latex, with 2 figures. To be published in the proceedings of the conference "Infrared Surveys: A Prelude to SIRTF"

We have obtained detailed imaging Fabry-Perot observations of the nearby galaxy M82, in order to understand the physical association between the high-velocity outflow and the starburst nucleus. The observed velocities of the emitting gas in M82 reveal a bipolar outflow of material, originating from the bright starburst regions in the galaxy's inner disk, but misaligned with respect to the galaxy spin axis. The deprojected outflow velocity increases with radius from 525 to 655 km/s. Spectral lines show double components in the centers of the outflowing lobes, with the H-alpha line split by ~300 km/s over a region almost a kiloparsec in size. The filaments are not simple surfaces of revolution, nor is the emission distributed evenly over the surfaces. We model these lobes as a composite of cylindrical and conical structures, collimated in the inner ~500 pc but expanding at a larger opening angle of ~25 degrees beyond that radius. We compare our kinematic model with simulations of starburst-driven winds in which disk material surrounding the source is entrained by the wind. The data also reveal a remarkably low [NII]/H-alpha ratio in the region of the outflow, indicating that photoionization by the nuclear starburst may play a significant role in the excitation of the optical filament gas, particularly near the nucleus., Comment: 42 pages AASTeX with 16 figures; accepted for publication in ApJ; figures reformatted for better printing

We present initial results from a redshift survey carried out with the Low Resolution Imaging Spectrograph on the 10~m W. M. Keck Telescope in the Hubble Deep Field. In the redshift distribution of the 140 extragalactic objects in this sample we find 6 strong peaks, with velocity dispersions of ${\sim}400${\kms}. The areal density of objects within a particular peak, while it may be non-uniform, does not show evidence for strong central concentration. These peaks have characteristics (velocity dispersions, density enhancements, spacing, and spatial extent) similar to those seen in a comparable redshift survey in a different high galactic latitude field (Cohen et al 1996), confirming that the structures are generic. They are probably the high redshift counterparts of huge galaxy structures (``walls'') observed locally., Comment: 14 pages, including 2 figures, to appear in ApJ Letters

This paper describes the technologies and services used in the experiments and demonstrations using the Trans-Pacific high data rate satellite communications infrastructure, and how the environment tasked protocol adaptability, scalability, efficiency, interoperability, and robustness.

In 1993, a proposal at the Japan-U.S. Cooperation in Space Program Workshop lead to a subsequent series of satellite communications experiments and demonstrations, under the title of Trans-Pacific High Data Rate Satellite Communications Experiments.

As introduced at ADASSI, a Fabry-Perot analysis package for IRAF is currently under development as a joint effort of ourselves and Frank Valdes of the IRAF group. Although additional portions of the package were also implemented, we report primarily on the development of a robust ring fitting task, useful for fitting the calibration rings obtained in Fabry-Perot observations. The general equation of an ellipse is fit to the shape of the rings, providing information on ring center, ellipticity, and position angle. Such parameters provide valuable information on the wavelength response of the etalon and the geometric stability of the system. Appropriate statistical weighting is applied to the pixels to account for increasing numbers with radius, the Lorentzian cross-section, and uneven illumination. The major problems of incomplete, non-uniform, and multiple rings are addressed with the final task capable of fitting rings regardless of center, cross-section, or completion. The task requires only minimal user intervention, allowing large numbers of rings to be fit in an extremely automated manner.

The statistical behavior of an idealized linear detector in the presence of threshold and saturation levels is examined. It is assumed that the noise is governed by the statistical fluctuations in the number of photons emitted by the source during an exposure. Since physical detectors cannot have infinite dynamic range, our model illustrates that all devices have non-linear regimes, particularly at high count rates. The primary effect is a decrease in the statistical variance about the mean signal due to a portion of the expected noise distribution being removed via clipping. Higher order statistical moments are also examined, in particular, skewness and kurtosis. In principle, the expected distortion in the detector noise characteristics can be calibrated using flatfield observations with count rates matched to the observations. For this purpose, some basic statistical methods that utilize Fourier analysis techniques are described.