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NASA’s James Webb Space Telescope (JWST) is a 6.6m diameter, segmented, deployable telescope for cryogenic IR space astronomy. The JWST Observatory architecture includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) element which contains four science instruments (SI), including a guider. The SIs and guider are mounted to a composite metering structure with outer envelope approximate measurements of 2.2x2.2x1.7m. These SI units are integrated to the ISIM structure and optically tested at NASA Goddard Space Flight Center as an instrument suite using an Optical telescope element SIMulator (OSIM). OSIM is a high-fidelity, cryogenic JWST simulator that features a ~1.5m diameter powered mirror. The SIs are aligned to the flight structure’s coordinate system under ambient, clean room conditions using opto-mechanical metrology and customized interfaces. OSIM is aligned to the ISIM mechanical coordinate system at the cryogenic operating temperature via internal mechanisms and feedback from alignment sensors and metrology in six degrees of freedom. SI performance, including focus, pupil shear, pupil roll, boresight, wavefront error, and image quality, is evaluated at the operating temperature using OSIM. This work reports on the as-run ambient assembly and ambient alignment steps for the flight ISIM, including SI interface fixtures and customization and kinematic mount adjustment. The ISIM alignment plan consists of multiple steps to meet the “absolute” alignment requirements of the SIs and OSIM to the flight coordinate system. In this paper, we focus on key aspects of absolute, optical-mechanical alignment. We discuss various metrology and alignment techniques. In addition, we summarize our approach for dealing with and the results of ground-test factors, such as gravity.

NASA’s James Webb Space Telescope (JWST) is a 6.5m diameter, segmented, deployable telescope for cryogenic IR space astronomy (~40K). The JWST Observatory architecture includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) element that contains four science instruments (SI), including a guider. OSIM is a full field, cryogenic, optical simulator of the JWST OTE. It is the “Master Tool” for verifying the cryogenic alignment and optical performance of ISIM by providing simulated point source/star images to each of the four Science Instruments in ISIM. Included in OSIM is a Pupil Imaging Module (PIM) - a large format CCD used for measuring pupil alignment. Located at a virtual stop location within OSIM, the PIM records superimposed shadow images of pupil alignment reference (PAR) targets located in the OSIM and SI pupils. The OSIM Pupil Imaging Module was described by Brent Bos, et al, at SPIE in 2011 prior to ISIM testing. We have recently completed the third and final ISIM cryogenic performance verification test before ISIM was integrated with the OTE. In this paper, we describe PIM implementation, performance, and measurement results.

OSIM is a full field, cryogenic, optical simulator of the James Webb Space Telescope (JWST) Optical Telescope Element (OTE). It is the “Master Tool” for verifying the cryogenic alignment and optical performance of the JWST Integrated Science Instrument Module (ISIM) by providing simulated point source/star images individually or simultaneously to each of the four Science Instruments in ISIM. Additionally, each star image can be scanned in focus to support the evaluation of both image quality and best focus for each Science Instrument. OSIM has recently completed supporting the ISIM performance verification test campaign which spanned three separate cryogenic test campaigns over 3 years. In this paper, we describe the alignment to the JWST coordinate system at cryogenic temperatures, OSIM optical performance, repeatability, and its role in testing the cryogenic optical performance of the individual Science Instruments in addition to providing calibration data needed for flight operations.

NASA's James Webb Space Telescope (JWST) is a 6.6m diameter, segmented, deployable telescope for cryogenic IR space astronomy (~40K). The JWST Observatory includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) that contains four science instruments (SI) and the fine guider. The SIs are mounted to a composite metering structure. The SI and guider units were integrated to the ISIM structure and optically tested at the NASA Goddard Space Flight Center as a suite using the Optical Telescope Element SIMulator (OSIM). OSIM is a full field, cryogenic JWST telescope simulator. SI performance, including alignment and wave front error, were evaluated using OSIM. We describe test and analysis methods for optical performance verification of the ISIM Element, with an emphasis on the processes used to plan and execute the test. The complexity of ISIM and OSIM drove us to develop a software tool for test planning that allows for configuration control of observations, associated scripts, and management of hardware and software limits and constraints, as well as tools for rapid data evaluation, and flexible re-planning in response to the unexpected. As examples of our test and analysis approach, we discuss how factors such as the ground test thermal environment are compensated in alignment. We describe how these innovative methods for test planning and execution and post-test analysis were instrumental in the verification program for the ISIM element, with enough information to allow the reader to consider these innovations and lessons learned in this successful effort in their future testing for other programs.

The James Webb Space Telescope includes the Integrated Science Instrument Module (ISIM) element that contains four science instruments (SI) including a Guider. We performed extensive structural, thermal, and optical performance(STOP) modeling in support of all phases of ISIM development. In this paper, we focus on modeling and results associated with test and verification. ISIMs test program is bound by ground environments, mostly notably the 1g and test chamber thermal environments. This paper describes STOP modeling used to predict ISIM system performance in 0g and at various on-orbit temperature environments. The predictions are used to project results obtained during testing to on-orbit performance.

The James Webb Space Telescopes segmented primary and deployable secondary mirrors will be actively con- trolled to achieve optical alignment through a complex series of steps that will extend across several months during the observatory's commissioning. This process will require an intricate interplay between individual wavefront sensing and control tasks, instrument-level checkout and commissioning, and observatory-level calibrations, which involves many subsystems across both the observatory and the ground system. Furthermore, commissioning will often exercise observatory capabilities under atypical circumstances, such as fine guiding with unstacked or defocused images, or planning targeted observations in the presence of substantial time-variable offsets to the telescope line of sight. Coordination for this process across the JWST partnership has been conducted through the Wavefront Sensing and Control Operations Working Group. We describe at a high level the activities of this group and the resulting detailed commissioning operations plans, supporting software tools development, and ongoing preparations activities at the Science and Operations Center. For each major step in JWST's wavefront sensing and control, we also explain the changes and additions that were needed to turn an initial operations concept into a flight-ready plan with proven tools. These efforts are leading to a robust and well-tested process and preparing the team for an efficient and successful commissioning of JWSTs active telescope.

Hubble Space Telescope Advanced Camera for Surveys images of the young binary GG Tauri and its circumbinary disk in V and I bandpasses were obtained in 2002 and are the most detailed of this system to date. They confirm features previously seen in the disk including a "gap" apparently caused by shadowing from circumstellar material, an asymmetrical distribution of light about the line of sight on the near edge of the disk, enhanced brightness along the near edge of the disk due to forward scattering, and a compact reflection nebula near the secondary star. New features are seen in the ACS images: two short filaments along the disk, localized but strong variations in the disk intensity ("gaplets"), and a "spur" or filament extending from the reflection nebulosity near the secondary. The back side of the disk is detected in the V band for the first time. The disk appears redder than the combined light from the stars, which may be explained by a varied distribution of grain sizes. The brightness asymmetries along the disk suggest that it is asymmetrically illuminated by the stars due to extinction by nonuniform circumstellar material or that the illuminated surface of the disk is warped by tidal effects (or perhaps both). Localized, time-dependent brightness variations in the disk are also seen.

We present the photometric calibration of the HST Advanced Camera for Surveys (ACS). We give here an overview of the performance and calibration of the 2 CCD cameras, the Wide Field Channel (WFC) and the High Resolution Channel (HRC), and a description of the best techniques for reducing ACS CCD data. On-orbit observations of spectrophotometric standard stars have been used to revise the pre-launch estimate of the instrument response curves to best match predicted and observed count rates. Synthetic photometry has been used to determine zeropoints for all filters in 3 magnitude systems and to derive interstellar extinction values for the ACS photometric systems. Due to the CCD internal scattering of long wavelength photons, the width of the PSF increases significantly in the near-IR and the aperture correction for photometry with near-IR filters depends on the spectral energy distribution of the source. We provide encircled energy curves and a detailed recipe to correct for the latter effect. Transformations between the ACS photometric systems and the UBVRI and WFPC2 systems are presented. In general, two sets of transformations are available: 1 based on the observation of 2 star clusters; the other on synthetic photometry. We discuss the accuracy of these transformations and their sensitivity to details of the spectra being transformed. Initial signs of detector degradation due to the HST radiative environment are already visible. We discuss the impact on the data in terms of dark rate increase, charge transfer inefficiency, and hot pixel population.

We investigate the physical nature of blue cores in early-type galaxies through the first multi-wavelength analysis of a serendipitously discovered field blue-nucleated spheroid in the background of the deep ACS/WFC griz multicolor observations of the cluster Abell 1689. The resolved g-r, r-i and i-z color maps reveal a prominent blue core identifying this galaxy as a ``typical'' case study, exhibiting variations of 0.5-1.0 mag in color between the center and the outer regions, opposite to the expectations of reddened metallicity induced gradients in passively evolved ellipticals. From a Magellan-Clay spectrum we secure the galaxy redshift at $z=0.624$. We find a strong X-ray source coincident with the spheroid galaxy. Spectral features and a high X-ray luminosity indicate the presence of an AGN in the galaxy. However, a comparison of the X-ray luminosity to a sample derived from the Chandra Deep Field South displays Lx to be comparable to Type I/QSO galaxies while the optical flux is consistent with a normal star-forming galaxy. We conclude that the galaxy's non-thermal component dominates at high-energy wavelengths while we associate the spheroid blue light with the stellar spectrum of normal star-forming galaxies. We argue about a probable association between the presence of blue cores in spheroids and AGN activity.

We present $V$ and $I$ continuum images and H$\alpha$+[N II] maps of nine early-type galaxies observed with the Wide Field Channel of the Advanced Camera for Surveys on the Hubble Space Telescope. Dust and ionized gas are detected in all galaxies. The optical nebulae are primarily concentrated on the nuclei and extend out to radii of a few hundred parsecs, in compact clumps, filaments, or disks. Two galaxies, NGC 6166 and NGC 6338, also possess diffuse, ionized filaments on kiloparsec scales. The ionized gas is entirely contained within the nuclear disks of ESO 208-G021, NGC 3078, and NGC 7720. In the radio-loud galaxy NGC 6166, emission-line filaments are detected along the radio lobes, possibly as a result of shock ionization. A wide range of ionized gas masses, $M_g\approx7\times10^2-3\times10^6$ $M_\odot$, are calculated from the observed fluxes. Even in this small sample, the orientation of the ionized material correlates well with the major or minor axis of the galaxies, consistent with an external origin for the dust and gas.

We present the analysis of the faint galaxy population in the Advanced Camera for Surveys (ACS) Early Release Observation fields VV 29 (UGC 10214) and NGC 4676. Here we attempt to thoroughly consider all aspects relevant for faint galaxy counting and photometry, developing methods which are based on public software and that are easily reproducible by other astronomers. Using simulations we determine the best SExtractor parameters for the detection of faint galaxies in deep HST observations, paying special attention to the issue of deblending, which significantly affects the normalization and shape of the number count distribution. We confirm, as claimed by Bernstein, Freedman and Madore (2002), that Kron-like magnitudes, such as the ones generated by SExtractor, can miss more than half of the light of faint galaxies, what dramatically affects the slope of the number counts. We present catalogs for the VV 29 and NGC 4676 fields with photometry in the g,V and I bands. We also show that combining the bayesian software BPZ with superb ACS data and new spectral templates enables us to estimate reliable photometric redshifts for a significant fraction of galaxies with as few as three filters. After correcting for selection effects, we measure slopes of 0.32+- 0.01 for 22 25.5 can be well approximated in all our filters by a passive luminosity evolution model based on the COMBO-17 luminosity function (\alpha=-1.5), with a strong merging rate following the prescription of Glazebrook et al. (1994), \phi^*\propto (1+Qz), with Q=4.

Using an i-z dropout criterion, we determine the space density of z~6 galaxies from two deep ACS GTO fields with deep optical-IR imaging. A total of 23 objects are found over 46 arcmin^2, or ~0.5 objects/arcmin^2 down to z~27.3 (6 sigma; all AB mag) (including one probable z~6 AGN). Combining deep ISAAC data for our RDCS1252-2927 field (J~25.7 and Ks~25.0 (5 sigma)) and NICMOS data for the HDF North (JH~27.3 (5 sigma)), we verify that these dropouts have flat spectral slopes. i-dropouts in our sample range in luminosity from ~1.5 L* (z~25.6) to ~0.3 L* (z~27.3) with the exception of one very bright candidate at z~24.2. The half-light radii vary from 0.09" to 0.29", or 0.5 kpc to 1.7 kpc. We derive the z~6 rest-frame UV luminosity density using three different procedures, each utilizing simulations based on a CDF South V dropout sample. First, we compare our findings with a no-evolution projection of this V-dropout sample. We find 23+/-25% more i-dropouts than we predict. Adopting previous results to z~5, this works out to a 20+/-29% drop in the luminosity density from z~3 to z~6. Second, we use these same V-dropout simulations to derive a selection function for our i-dropout sample and compute the UV-luminosity density (7.2+/-2.5 x 10^25 ergs/s/Hz/Mpc^3 down to z~27). We find a 39+/-21% drop over the same redshift range. This is our preferred value and suggests a star formation rate of 0.0090+/-0.0031 M_sol/yr/Mpc^3 to z~27, or ~0.036+/- 0.012 M_sol/yr/Mpc^3 extrapolating the LF to the faint limit. Third, we follow a very similar procedure, but assume no incompleteness, finding a luminosity density which is ~2-3X lower. This final estimate constitutes a lower limit. All three estimates are within the canonical range of luminosity densities necessary for reionization of the universe at this epoch. (abridged)

Multicolor coronagraphic images of the circumstellar disk around HD141569A have been obtained with the Hubble Space Telescope (HST) Advanced Camera for Surveys. B, V, and I images show that the disk's previously-described multiple-ring structure is actually a continuous distribution of dust with a tightly-wound spiral structure. Two, more open spiral arms extend from the disk, one of which appears to reach the nearby binary star HD141569BC. Diffuse dust is seen up to 1200AU from HD141569A. Although planets may exist in the inner region of the disk, tidal interaction with HD141569BC seems more likely to be the cause of these phenomena. The disk appears redder than the star (B-V = 0.21 and V-I = 0.25), and its color is spatially uniform. A scattering asymmetry factor of g = 0.25-0.35 is derived. The azimuthal density distribution is asymmetric, varying by a factor of ~3 at some radii.

The nearby and luminous QSO 3C 273 was imaged in 2002 July with the High Resolution Channel (HRC) of the Advanced Camera for Surveys (ACS) in coronagraphic mode in F475W (g), F606W (V), and F814W (I) as part of the Early Release Observations (ERO) program. After subtraction of the remaining PSF of the QSO, these images offer the most detailed view yet of the morphology and colors of the host galaxy of this QSO. We find that the central light distribution is elongated along the jet axis and its outer edge is delineated by an arc, centered on the jet at a radius of ~26 from the QSO and bluer than the surrounding galaxy. This system is embedded in an extended galactic halo. Compared with early-type galaxies of similar redshifts and luminosities, the light distribution of 3C 273 is flatter in the core, likely from suppression by dust, but similar in the outer halo. The QSO is displaced from the isophotal center of the galaxy by ~14. Previously known emission-line extensions are confirmed and new morphological features are identified, including a dramatic spiral-shaped plume, two faint filaments, a dust lane, and a knot along the jet axis. Part of the inner jet is unambiguously detected in all three bandpasses, and its morphology matches that of a MERLIN radio map. Different mechanisms that could explain the morphology of 3C 273 are considered, such as scattered QSO radiation, a face-on disk, and a merger event.

The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop workbench to study aspects of wavefront sensing and control for a segmented space telescope, including both commissioning and maintenance activities. JOST is complementary to existing optomechanical testbeds for JWST (e.g. the Ball Aerospace Testbed Telescope, TBT) given its compact scale and flexibility, ease of use, and colocation at the JWST Science & Operations Center. We have developed an optical design that reproduces the physics of JWST's three-mirror anastigmat using three aspheric lenses; it provides similar image quality as JWST (80% Strehl ratio) over a field equivalent to a NIRCam module, but at HeNe wavelength. A segmented deformable mirror stands in for the segmented primary mirror and allows control of the 18 segments in piston, tip, and tilt, while the secondary can be controlled in tip, tilt and x, y, z position. This will be sufficient to model many commissioning activities, to investigate field dependence and multiple field point sensing & control, to evaluate alternate sensing algorithms, and develop contingency plans. Testbed data will also be usable for cross-checking of the WFS&C Software Subsystem, and for staff training and development during JWST's five- to ten-year mission., Proceedings of the SPIE, 9143-150. 13 pages, 8 figures

This paper presents the results of an analysis of the Milky Way absorption lines found in the Hubble Space Telescope (HST) Quasar Absorption Line Key Project database for 83 QSOs observed with the Faint Object Spectrograph G190H and G270H gratings, of which 16 QSOs are also observed with the G130H grating. The HST Key Project observations are supplemented with high-quality 21 cm H I emission-line observations mostly obtained with the NRAO 43 m radio telescope. The Milky Way halo gas exhibits "mixed ionization" absorption with high-ionization absorption from Si IV and C IV substantially weaker than the extremely strong intermediate- and low-ionization absorption from Si III, Si II, C II, Mg II, and Fe II. For a sample of 16 QSOs observed in the far-UV, the median velocity equivalent widths of very strong lines of Si IV, Si III, and Si II are 60, 180, and 180 km s-1, respectively. Velocity equivalent widths this large for Si III and Si II imply the existence of high velocity dispersion moderate- (Si III) and low-ionization (Si II) gas along many paths through the Galactic halo. Measures of the Galactic damped Lyα line toward 14 QSOs permit the determination of N(H I)Lyα through the gaseous disk and halo of the Galaxy. The values of N(H I)Lyα range from 0.64 × 1020 to 3.37 × 1020 cm-2 with N(H I)Lyα| sin b| averaging (1.29 ± 0.49) × 1020 cm-2. A comparison of N(H I)Lyα with N(H I)21 cm reveals that N(H I)Lyα/N(H I)21 cm for the 10 sight lines where the value of N(H I)Lyα is not significantly affected by geocoronal emission ranges from 0.62 and 0.91. This difference is probably produced by a combination of systematic and random errors and contribution from the small angular scale structure in the H I distribution. Such structure can produce different column densities when sampling gas with an infinitesimal beam in the UV (the angular size of the QSO) compared to the much larger 21' beam of the NRAO 43 m radio telescope. The overall strength of the Mg II λλ2796 and 2803 absorption appears to be correlated with the presence of high-velocity gas along the line to sight. Velocity-resolved Mg II absorption associated with high-velocity gas in the Magellanic Stream is detected toward eight QSOs, including PKS 0003+15, PG 0043+039, PKS 0637-75, 3C 454.3, PKS 2251+11, PG 2302+029, PKS 2340-36, and PKS 2344+09. Velocity-resolved Mg II absorption toward 15 QSOs is not accompanied by the existence of associated H I emission. Interesting objects in this category include PKS 0232-04 (l = 1745, b = -562), which has a high-velocity cloud (HVC) at v ~ +270 km s-1 detected in Mg II, and PG 1116+215 (l = 2233,b = 682) with a HVC at +200 km s-1 detected in Mg II, C II, Si IV, and possibly C IV. The HVC toward PKS 0232-04 is interesting because all known H I HVCs in this general region of the sky have negative velocity rather than positive velocity. For 15 QSOs known to lie in the direction of H I HVCs, the Mg II lines have extremely strong principal absorption components, suggesting the detection of blended low- and high-velocity absorption. These lines of sight imply the detection of Mg II absorption by the high-velocity gas in HVC complexes C and A, in the outer Galaxy warp, and in the Magellanic Stream, as well as toward three smaller clouds. There are 11 QSO sight lines with very strong Mg II absorption for which there is no evidence for high-velocity H I emission. However, six of these sight lines lie near known H I HVCs. There are 38 QSOs with weak Mg II principal absorption and no known H I HVCs. These objects provide information about the H I absorption characteristics of disk and halo gas well away from H I HVCs. The sky covering factor of high-velocity Mg II is large, with 41 and 71 QSO lines of sight showing either resolved high-velocity Mg II absorption or principal absorption that is so strong that blended low- and high-velocity Mg II absorption is suggested.

We present an analysis of the evolution of the Ly alpha absorption lines in the redshift interval 0.0 to \sim 1.5 based upon a sample of 987 lines identified in the spectra of 63 QSOs obtained with the Faint Object Spectrograph on the Hubble Space Telescope. Fits to the number of absorbers per unit redshift dN/dz = A \times (1+z)^\gamma yield values of \gamma in the range 0.1 to 0.3, decidedly flatter than results from groundbased data pertaining to the redshift range z > 1.7. The combination of the space and groundbased data suggest a marked transition in the rate of evolution of the Ly alpha lines at a redshift of about 1.7. The distribution in redshift is well represented by a power law and the distribution of equivalent widths above a rest equivalent width of 0.1 \AA is fit well by an exponential. The sample of Ly alpha systems which has ions from heavy elements has a much larger value of \gamma than a sample of lines of comparable strength without heavy elements. We argue that this is not likely due to either line misidentification or incomplete spectral coverage and suggest that it is due to rapid evolution of the very highest column density systems, rather than differences in metallicity. We also find evidence that the rate of evolution increases with increasing equivalent width. We compare our results for the variation of line density with redshift to recent numerical simulations of Ly alpha absorbers, and find fairly good agreement. Our results for the stronger Ly alpha lines in our sample are compatible with the recent analysis of the absorber--galaxy correlation by Chen et al. 1998 but for the weaker lines our results suggest that the association between absorbers and galaxies is different from that for the stronger lines.

The Space Telescope Imaging Spectrograph (STIS) instrument was installed on the Hubble Space Telescope (HST) during the second servicing mission, in 1997 February. Four bands cover the wavelength range of 115–1000 nm, with spectral resolving powers between 26 and 200,000. Camera modes are used for target acquisition and deep imaging. Correction for HST's spherical aberration and astigmatism is included. The 115–170 nm range is covered by a CsI MAMA (Multianode Microchannel Array) detector and the 165–310 nm range by a Cs2Te MAMA, each with a format of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cy...

We present a catalogue of absorption lines obtained from the analysis of the ultra-violet spectra of 66 quasars. The data were acquired with the Faint Object Spectrograph of the HST as part of the Quasar Absorption Line Survey, a Key Project for the first four cycles of HST observations. This is the third of a series of catalogues of absorption lines produced from the survey and increases the number of quasars whose higher resolution (R=1300) spectra we have published from 17 to 83. The general properties and execution of the survey are reviewed, including descriptions of the final sample of observed objects and the algorithmic processes used to construct the catalogue. The detection of a single damped Ly-a system in a path length of Delta_z=49 yields an observed number of damped systems per unit redshift of (dN/dz)_{damp}(z=0.58)=0.020 with 95% confidence boundaries of 0.001 to 0.096 systems per unit redshift. We include notes on our analysis of each of the observed quasars and the absorption systems detected in each spectrum. Some especially interesting systems include low redshift Ly-a absorbers suitable for extensive follow-up observations (in the spectra of TON28 and PG1216+069), possibly physically associated pairs of extensive metal line absorption systems (e.g., in the spectrum of PG0117+213), and systems known to be associated with galaxies (e.g., in the spectrum of 3C232)., 27 pages, LaTeX file (no figs. and tables). Full version of article (including figures and tables) plus separate files for figures and tables available at http://www.sns.ias.edu/~jnb/Papers/Preprints/quasarablines.html To appear in ApJ Suppl, Vol. 118, 10/98. Correction of mislisted object in abstract and body of the paper

The nuclear region of M87 was observed with the Faint Object Spectrograph (FOS)on the Hubble Space Telescope (HST) at 6 epochs, spanning 18 months, after the HSTimage quality was improved with the deployment of the corrective optics (COSTAR)in December 1993. From the FOS target acquisition data, we have established that theflux from the optical nucleus of M87 varies by a factor ∼2 on time scales of ∼2.5 monthsand by as much as 25% over 3 weeks, and remains unchanged (∼< 2.5%) on time scalesof ∼ 1 day. The changes occur in an unresolved central region ∼< 5 pc in diameter,with the physical size of the emitting region limited by the observed time scales to afew hundred gravitational radii. The featureless continuum spectrum becomes blueras it brightens while emission lines remain unchanged. This variability combined withthe observations of the continuum spectral shape, strong relativistic boosting and thedetection of significant superluminal motions in the jet, strongly suggest that M87belongs to the class of BL Lac objects but is viewed at an angle too large to reveal theclassical BL Lac properties.Subject headings: galaxies: individual (M87) — galaxies: active — galaxies: nuclei —BL Lacertae objetcs: general1. INTRODUCTIONVariability is a fundamental property of Active Galactic Nuclei (AGN). In fact, it was the rapidchanges of the observed optical continuum fluxof quasars that led early researchers to the conclusion

The Space Telescope Imaging Spectrograph (STIS) was successfully installed into the Hubble Space Telescope (HST) in 1997 February, during the second HST servicing mission, STS-82. STIS is a versatile spectrograph, covering the 115-1000 nm wavelength range in a variety of spectroscopic and imaging modes that take advantage of the angular resolution, unobstructed wavelength coverage, and dark sky offered by the HST. In the months since launch, a number of performance tests and calibrations have been carried out and are continuing. These tests demonstrate that the instrument is performing very well. We present here a synopsis of the results to date.

We report early observations with Space Telescope Imaging Spectrometer (STIS) of the nuclear region of NGC 4151. Direct images in [O II] and [O III] and slitless medium-dispersion spectral images of the Hβ to [O III] region were obtained. A slitless UV spectral image was taken of the C IV 1550 A region. We present radial velocities and line ratios of ~40 clouds resolved in the narrow-line region (NLR). The kinematics suggest outflow within a biconical region about the nucleus, centered on the radio axis and viewed near the edge of the cones. A few high-velocity clouds are seen that do not fit this simple picture. Line ratios indicate that the NLR gas is photoionized by the central continuum source and that there may be a density gradient in the NLR. These observations are being followed by an extensive STIS program on NGC 4151.

We report the discovery of a high-ionization broad absorption line system at a redshift of z_abs=0.695 in the spectrum of the z_em=1.052 radio-quiet quasar PG 2302+039. Broad absorption with FWHM from 3,000 to 5,000 km/s is detected from C IV, N V, and O VI in HST Faint Object Spectrograph spectra of the quasar. A narrow line system (FWHM approximately 250 km/s) at z_abs=0.7016 is resolved from the broad blend and includes absorption by Ly-alpha and the C IV, N V, and O VI doublets. No absorption by low-ionization metal species (e.g. Si II and Mg II) is detected in the HST or ground-based spectra for either the broad or the narrow system. The centroids of the broad system lines are displaced by approximately 56,000 km/s to the blue of the quasar's broad emission lines. The reddest extent of the broad line absorption is more than 50,000 km/s from the quasar. The properties of this system are unprecedented whether it is an intervening or an ejected system.

The Cosmic Origins Spectrograph (COS) was installed into the Hubble Space Telescope (HST) during Servicing Mission 4 (SM4) in May 2009. COS is designed to obtain spectra of faint objects at moderate spectral resolution (R > 16,000) in two channels: FUV, covering wavelengths from 1150 to 1450 A; and NUV, covering 1700 - 3200 A. Two low resolution gratings (R > 1500) cover the < 900 - 2050 A (FUV) and 1650 - 3200 A (NUV) wavelength regions. An imaging capability is also available on the NUV channel. As part of the Hubble Servicing Mission Observatory Verification (SMOV) program, an extensive period of checkout, fine-tuning and preliminary characterization began after the installation of COS. The COS SMOV program was a cooperative effort between the Space Telescope Science Institute and the Instrument Definition Team based at the University of Colorado. Nearly 2800 COS exposures in 34 separate observing programs were obtained during the course of SMOV. Early activities included an initial instrument functional checkout, turn-on and initial characterization of the detectors, NUV and FUV channel focus and alignment, and target acquisition verification and assessment. Once this initial period was completed, science-related calibrations and verifications were performed in order to prepare the instrument for normal science operations. These activities included wavelength calibration, flux calibration, detector flat field characterization, spectroscopic performance verification, high S/N operation, and thermal and structural stability measurements. We discuss the design, execution and results of the SMOV program, including the interrelationships between the various tasks, and how the pre-launch plan was adjusted in real-time due to changing conditions.

The Wide-field Camera 3 (WFC3) is a fourth-generation instrument planned for installation in Hubble Space Telescope (HST). Designed as a panchromatic camera, WFC3's UVIS and IR channels will complement the other instruments onboard HST and enhance the observatory's scientific performance. UVIS images are obtained via two 4096x2051 pixel e2v CCDs while the IR images are taken with a 1024x1024 pixel HgCdTe focal plane array from Teledyne Imaging Sensors. Based upon characterization tests performed at NASA/GSFC, the final flight detectors have been chosen and installed in the instrument. This paper summarizes the performance characteristics of the WFC3 flight detectors based upon component and instrument-level testing in ambient and thermal vacuum environments.

The nuclear spectrum of M87 covering the Ly_a-H_a wavelength range was obtained with the HST Faint Object Spectrograph (FOS) trough a 0.21 arcsec aperture. Contrary to some previous claims, a single power law (F(nu)~nu^(-a)) can not reproduce the observed continuum shape and at least a broken power law is require for a good fit (a = 1.75 and 1.41 shortward and longward of the break at ~4500 A). We detect a set of broad (FWHM ~ 400 km/s) absorption lines arising in the gas associated with M87. These are only lines from neutral and very low ionization species blueshifted by ~150 km/s relative to the M87 systemic velocity, indicating a net gas outflow and turbulence. The excitation sensitive emission line ratios suggest that shocks may be the dominant energy supplier. The nuclear source in M87 is significantly variable. From the FOS target acquisition data, we have established that the flux from the optical nucleus varies by a factor ~2 on time scales of ~2.5 months and by as much as 25% over 3 weeks, and remains unchanged (

High-energy particles that induce a glow on the ZnCdTe substrate of the HgCdTe detectors of WFC3 may increase the background noise and reduce the scientific performance of the instrument. To eliminate this problem, a second generation of infrared detectors with substrate removed is under construction. Early tests indicate that the glow problem is eliminated and the quantum efficiency increases dramatically at shorter wavelengths, potentially providing a substantial improvement in the limiting sensitivity of the instrument.

Wide-Field Camera 3 (WFC3) has been built for installation on the Hubble Space Telescope (HST) during the next servicing mission. The WFC3 instrument consists of both a UVIS and an IR channel, each with its own complement of filters. On the UVIS side, a selectable optical filter assembly (SOFA) contains a set of 12 wheels that house 48 elements (42 full-frame filters, 5 quadrant filters, and 1 UV grism). The IR channel has one filter wheel which houses 17 elements (15 filters and 2 grisms). While the majority of UVIS filters exhibited excellent performance during ground testing, a subset of filters showed filter ghosting; improved replacements for these filters have been procured and installed. No filter ghosting was found in any of the IR filters; however, the new IR detector for WFC3 will have significantly more response blueward of 800 nm than the original detector, requiring that two filters originally constructed on a fused silica substrate be remade to block any visible light transmission. This paper summarizes the characterization of the final complement of the WFC3 UVIS and IR filters, highlighting improvements in the replacement filters and the projected benefit to science observations.

著者人数：43名, Accepted: 2006-02-13, 資料番号: SA1000396000

著者人数：44名, Accepted: 2005-11-22, 資料番号: SA1000634000

We present Hubble Space Telescope Advanced Camera for Surveys multicolor coronagraphic images of the recently discovered edge-on debris disk around the nearby (� 10 pc) M dwarf AU Microscopii. The disk is seen between r ¼ 0B75 and 15 00 (7.5–150 AU) from the star. It has a thin midplane with a projected FWHM thickness of 2.5–3.5 AU within r < 50 AU of the star that increases to 6.5–9 AU at r � 75 AU. The disk’s radial brightness profile is generally flat forr < 15 AU, then decreases gradually (I / r � 1:8 )o ut tor � 43 AU, beyond which it falls rapidly (I / r � 4:7 ). Within 50 AU the midplane is straight and aligned with the star, and beyond that it deviates by � 3 � , resulting in a bowed appearance that was also seen in ground-based images. Three-dimensional modeling of the disk shows that the inner region (r < 50 AU) is inclined to the line of sight by less than 1 � and the outer disk by � 3 � . The inclination of the outer disk and moderate forward scattering (g � 0:4) can explain the apparentbow. The intrinsic, deprojected FWHM thickness is 1.5–10 AU, increasing with radius. The models indicate that the disk is clear of dust within � 12 AU of the star, in general agreement with the previous prediction of 17 AU based on the infrared spectral energy distribution. The disk is blue, being 60% brighter at B than I relative to the star. One possible explanation for this is that there is a surplus of very small grains compared with other imaged debris disks that have more neutral or red colors. This may be due to the low radiation pressure exerted by the late-type star. Observations at two epochs show that an extended source seen along the midplane is a background galaxy.

We present new measurements of the galaxy luminosity function (LF) and its dependence on local galaxy density, color, morphology, and clustocentric radius for the massive z=0.83 cluster MS1054-0321. Our analyses are based on imaging performed with the ACS onboard the HST in the F606W, F775W and F850LP passbands and extensive spectroscopic data obtained with the Keck LRIS. Our main results are based on a spectroscopically selected sample of 143 cluster members with morphological classifications derived from the ACS observations. Our three primary findings are (1) the faint-end slope of the LF is steepest in the bluest filter, (2) the LF in the inner part of the cluster (or highest density regions) has a flatter faint-end slope, and (3) the fraction of early-type galaxies is higher at the bright end of the LF, and gradually decreases toward fainter magnitudes. These characteristics are consistent with those in local galaxy clusters, indicating that, at least in massive clusters, the common characteristics of cluster LFs are established at z=0.83. We also find a 2sigma deficit of intrinsically faint, red galaxies (i-z>0.5, Mi>-19) in this cluster. This trend may suggest that faint, red galaxies (which are common in z30 Mpc^-2, coinciding with the environment where the galaxy star formation rate and the morphology-density relation start to appear. (abridged), ApJ in press, references updated

The Extrasolar Planetary Imaging Coronagraph (EPIC) is a proposed NASA Discovery mission to image and characterize extrasolar giant planets in orbits with semi-major axes between 2 and 10 AU. EPIC will provide insights into the physical nature of a variety of planets in other solar systems complimenting radial velocity (RV) and astrometric planet searches. It will detect and characterize the atmospheres of planets identified by radial velocity surveys, determine orbital inclinations and masses, characterize the atmospheres around A and F type stars which cannot be found with RV techniques, and observe the inner spatial structure and colors of debris disks. EPIC has a proposed launch date of 2012 to heliocentric Earth trailing drift-away orbit, with a 3 year mission lifetime (5 year goal), and will revisit planets at least three times at intervals of 9 months. The robust mission design is simple and flexible ensuring mission success while minimizing cost and risk. The science payload consists of a heritage optical telescope assembly (OTA), and visible nulling coronagraph (VNC) instrument. The instrument achieves a contrast ratio of 109 over a 4.84 arcsecond field-of-view with an unprecedented inner working angle of 0.14 arcseconds over the spectral range of 440-880 nm, with spectral resolutions from 10 - 150. The telescope is a 1.5 meter offaxis Cassegrain with an OTA wavefront error of λ/9, which when coupled to the VNC greatly reduces the requirements on the large scale optics, compressing them to stability requirements within the relatively compact VNC optical chain. The VNC features two integrated modular nullers, a spatial filter array (SFA), and an E2V-L3 photon counting CCD. Direct null control is accomplished from the science focal mitigating against complex wavefront and amplitude sensing and control strategies.

The Wide Field Camera 3 (WFC3) instrument was designed and built to replace the Hubble Space Telescope (HST) instrument Wide Field and Planetary Camera 2 (WF/PC2) and to provide improved ultra-violet through near infrared imaging capability over the extended HST mission. We describe the optical component integration, alignment, and performance testing of the optical bench assembly.

The Advanced Camera for Surveys (ACS), installed in the Hubble Space Telescope (HST) in March 2002, comprises three cameras: the Wide Field Camera (WFC), designed for deep near-IR survey imaging programs; the High Resolution Camera (HRC), a high angular resolution imager which fully samples the HST full spread function (PSF) in the visible; and the Solar Blind Camera (SBC), a far-UV imager. The WFC and HRC employ CCD detectors. Their performances are affected by the on-going damage due to the space radiation environment where they operate. We present an overview of the performance of the ACS CCD detectors, based on the first two years of flight science operations. We analyze the evolution with time of the basic detector performance that are subjected to degradation due to the on-going radiation damage. Comparison is made with ground testing prediction and with the amount of performance degradation seen in other CCD detectors on board of HST.

The Advanced camera for Surveys (ACS), installed in the Hubble Space telescope in March 2002, has significantly extended HST’s deep, survey imaging capabilities. ACS comprises three cameras: the Wide Field Camera (WFC) is designed for deep, near-IR survey imaging programs; the High Resolution Camera (HRC) is a high angular resolution imager/coronagraph, which fully samples the HST point spread function in the visible; and the Solar Blind Camera (SBC) is a far-UV imager. ACS has met, or exceeded all of its key performance specification. In this paper we briefly review the in-flight performances of the instrument's CCD detectors. We present an overview of the performance of the ACS CCD detectors, based on the first year of flight science operations.

The most massive galaxies and the richest clusters are believed to have emerged from regions with the largest enhancements of mass density relative to the surrounding space. Distant radio galaxies may pinpoint the locations of the ancestors of rich clusters, because they are massive systems associated with overdensities of galaxies that are bright in the Lyman-alpha line of hydrogen. A powerful technique for detecting high-redshift galaxies is to search for the characteristic `Lyman break' feature in the galaxy colour, at wavelengths just shortwards of Lya, due to absorption of radiation from the galaxy by the intervening galactic medium. Here we report multicolour imaging of the most distant candidate protocluster, TN J1338-1942 at a redshift z=4.1. We find a large number of objects with the characteristic colours of galaxies at that redshift, and we show that this excess is concentrated around the targeted dominant radio galaxy. Our data therefore indicate that TN J1338-1942 is indeed the most distant cluster progenitor of a rich local cluster, and that galaxy clusters began forming when the Universe was only 10 per cent of its present age., 6 pages, 2 figures, Letter to Nature (1 Jan. 2004 v427)

The properties of Ultra Compact Dwarf (UCD) galaxy candidates in Abell 1689 (z=0.183) are investigated, based on deep high resolution ACS images. A UCD candidate has to be unresolved, have i 26.8 mag, the radial and luminosity distribution of the UCD candidates can be explained well by Abell 1689's globular cluster (GC) system. For i

We present the preliminary calibration results for the Cosmic Origins Spectrograph, a fourth generation replacement instrument for the Hubble Space Telescope due to be installed in mid-2005. The Cosmic Origins Spectrograph consists of two spectroscopic channels: a far ultraviolet channel that observes wavelengths between 1150 and 2000 aand a near ultraviolet channel that observes between 1700 and 3200 a. Each channel supports moderate (R≈20,000) and low (R≈2000) spectral resolution. We discuss the calibration methodology, test configurations, and preliminary end-to-end calibration results. This includes spectral resolution, system efficiency, flat fields, and wavelength scales for each channel. We also present the measured transmission of the Bright Object Aperture (BOA) and the measured spatial resolution.

We investigate the color-magnitude (CM) relation of galaxies in the distant X-ray selected cluster RDCS1252.9-2927 at z=1.24 using images obtained with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope in the F775W and F850LP bandpasses. We select galaxies based on morphological classifications extending about 3.5 mag down the galaxy luminosity function, augmented by spectroscopic membership information. At the core of the cluster is an extensive early-type galaxy population surrounding a central pair of galaxies that show signs of dynamical interaction. The early-type population defines a tight sequence in the CM diagram, with an intrinsic scatter in observed (i-z) of $0.029\pm0.007$ mag based on 52 galaxies, or $0.024\pm0.008$ mag for $\sim30$ ellipticals. Simulations using the latest stellar population models indicate an age scatter for the ellipticals of about 34%, with a mean age $\taul\gta2.6$ Gyr (corresponding to $z_L\gta2.7$), and the last star formation occurring at $z_{end}\gta1.5$. Transforming to rest-frame $(U-B)$, we conclude that the slope and scatter in the CM relation for morphologically selected early-type galaxies show little or no evidence for evolution out to $z\approx1.2$. Thus, elliptical galaxies were already well established in X-ray luminous clusters when the universe was a third of its present age., Comment: 6 emulateapj pages with 4 figures, including a bonus figure not seen elsewhere. Accepted for publication in ApJ Letters. A version with a higher resolution fig 1 can be found at http://acs.pha.jhu.edu/~jpb/z1clusters/

The most massive galaxies and the richest clusters are believed to have emerged from regions with the largest enhancements of mass density relative to the surrounding space. Distant radio galaxies may pinpoint the locations of the ancestors of rich clusters, because they are massive systems associated with 'overdensities' of galaxies that are bright in the Lyman-alpha line of hydrogen. A powerful technique for detecting high-redshift galaxies is to search for the characteristic 'Lyman break' feature in the galaxy colour, at wavelengths just shortwards of Lyalpha, which is due to absorption of radiation from the galaxy by the intervening intergalactic medium. Here we report multicolour imaging of the most distant candidate protocluster, TN J1338-1942 at a redshift z approximately 4.1. We find a large number of objects with the characteristic colours of galaxies at that redshift, and we show that this excess is concentrated around the targeted dominant radio galaxy. Our data therefore indicate that TN J1338-1942 is indeed the most distant cluster progenitor of a rich local cluster, and that galaxy clusters began forming when the Universe was only ten per cent of its present age.

PRIME (The Primordial Explorer) is a proposed Explorer-class mission. Aimed at the “first light” in the Universe, it will carry out a deep sky survey from space in four near-infrared bands between ~1-3.5 P ,W VXUYH\V D TXDUWHU RI WKHsky to AB magnitude of ~24, which is ~600 times deeper than 2MASS and ~ five million times deeper than COBE at long wavelengths. Deeper surveys in selected sky regions are also planned. PRIME will reach an epoch during which the first quasars, galaxies and clusters of galaxies were formed in the early universe, map the large-scale structure of the dark matter, discover Type-Ia supernovae to be used in measuring the acceleration of the expanding universe, and detect thousands of brown dwarfs and even Jupiter-size planets in the vicinity of the solar system. Most of these objects are so rare that they may be identified only in large and deep surveys. PRIME will serve as the precursor for the Next Generation Space Telescope ( NGST ), supplying rare targets for its spectroscopy and deep imaging. It is more than capable of providing targets for the largest ground-based telescopes (10-30m). Combining PRIME with other surveys (SDSS, GALEX) will yield the largest astronomical database ever built. Keywords: survey, galaxy, quasar

The ACS solar blind channel (SBC) is a photon-counting MAMA detector capable of producing two-dimensional imaging in the UV at wavelengths 1150-1700 Angstroms, with a field of view (FOV) of 31" × 35". We describe the on-orbit performance of the ACS/SBC from an analysis of data obtained from the service mission observatory verification (SMOV) programs. Our summary includes assessment of the point-source image quality and point spread function (PSF) over the SBC FOV, the dark current measurements, the characteristics of the flat fields, fold analysis, throughput, and the UV sensitivity monitor to check for contamination. Where appropriate, a comparison with pre-launch calibration data will also be made.

We present an overview of the Advanced Camera for Surveys (ACS) CCD detectors performance based on the ground testing and the calibration observations taken during the first four months of ACS operation. ACS has been installed into the Hubble Space Telescope in March 2002 and consists of three different cameras. Two of them employ CCD detectors: the Wide Field Camera a mosaic of two 4096 x 2048 CCDs and the High Resolution Camera a single 1024 x 1024 chip. A review of the on-orbit performance is presented here and also comparison is made with the instrument specifications, published performance expectation and ground test results.

The off-axis location of the Advanced Camera for Surveys causes strong geometric distortion in all detectors -- the Wide Field Camera (WFC), High Resolution Camera (HRC), and Solar Blind Camera (SBC). Dithered observations of rich star cluster fields are used to calibrate the distortion. We describe the observations obtained, the algorithms used to perform the calibrations and the accuracy achieved. We present our best current calibration of the geometric distortion of each of the detectors.

The Advanced Camera for Surveys (ACS), installed in the Hubble Space Telescope in March 2002, has significantly extended HST’s imaging capabilities. We describe the on-orbit optical alignment procedures and results, detailing the excellent image quality performance achieved. Comparison is made with the instrument specifications, ground test results and published performance expectations. The residual aberration content over the field of each channel is described and compared with the optical model, and various other performance measures, including sharpness and encircled energy are treated. The effects of the telescope focus oscillations due to thermal variations ("breathing") and image positional stability are also discussed.

We present an overview of the ACS on-orbit performance based on the calibration observations taken during the first three months of ACS operations. The ACS meets or exceeds all of its important performance specifications. The WFC and HRC FWHM and 50% encircled energy diameters at 555 nm are 0.088" and 0.14", and 0.050" and 0.10". The average rms WFC and HRC read noises are 5.0 e- and 4.7 e-. The WFC and HRC average dark currents are ~ 7.5 and ~ 9.1 e-/pixel/hour at their operating temperatures of - 76°C and - 80°C. The SBC + HST throughput is 0.0476 and 0.0292 through the F125LP and F150LP filters. The lower than expected SBC operating temperature of 15 to 27°C gives a dark current of 0.038 e-/pix/hour. The SBC just misses its image specification with an observed 50% encircled energy diameter of 0.24" at 121.6 nm. The ACS HRC coronagraph provides a 6 to 16 direct reduction of a stellar PSF, and a ~1000 to ~9000 PSF-subtracted reduction, depending on the size of the coronagraphic spot and the wavelength. The ACS grism has a position dependent dispersion with an average value of 3.95 nm/pixel. The average resolution λ/Δλ for stellar sources is 65, 87, and 78 at wavelengths of 594 nm, 802 nm, and 978 nm.