Status Report

NASA Hubble Space Telescope Daily Report #3982

By SpaceRef Editor
November 7, 2005
Filed under , ,
NASA Hubble Space Telescope Daily Report #3982

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT November 04,05,06, 2005 (DOY 308,309,310)


ACS/HRC 9973

Intensive Coverage of the Eta Carinae Event in 2003

For a variety of reasons, HST can provide a very special and unique data set when Eta Car experiences its next spectroscopic event in mid-2003. Explaining the phenomenon is only part of the motivation. This star and its ejecta have unique characteristics that make them important for several branches of astrophysics; and when a spectroscopic event occurs, it’s like varying the parameters in an experiment {or rather, set of experiments}. The 2003 event may be the only chance in the forseeable future to obtain such a data set, especially with HST. Eta Carinae has extreme parameters; it is mysterious in surprisingly basic ways; and HST/ACS/HRC can gather useful data on it at a terrific rate. As we explain below, the proposed data set will be valuable in several independent ways: It will help solve a specific set of current problems, it will constitute a large and unique archival data base for both stellar and nebular astrophysics, and it will be well- suited for educational uses.

FGS 9335

Masses of Pre-Main Sequence Binaries

We propose to continue to map the orbits of young star binaries in the Taurus and Ophiuchus star forming regions. Our goal is to measure their masses dynamically. This is important because there are still no low mass young stars with reliably known masses so calculations of their evolution to the main sequence are uncalibrated.

NIC1/NIC2/NIC3 8793

NICMOS Post-SAA calibration – CR Persistence Part 4

A new procedure proposed to alleviate the CR-persistence problem of NICMOS. Dark frames will be obtained immediately upon exiting the SAA contour 23, and every time a NICMOS exposure is scheduled within 50 minutes of coming out of the SAA. The darks will be obtained in parallel in all three NICMOS Cameras. The POST-SAA darks will be non-standard reference files available to users with a USEAFTER date/time mark. The keyword ‘USEAFTER=date/time’ will also be added to the header of each POST-SAA DARK frame. The keyword must be populated with the time, in addition to the date, because HST crosses the SAA ~8 times per day so each POST-SAA DARK will need to have the appropriate time specified, for users to identify the ones they need. Both the raw and processed images will be archived as POST-SAA DARKSs. Generally we expect that all NICMOS science/calibration observations started within 50 minutes of leaving an SAA will need such maps to remove the CR persistence from the science images. Each observation will need its own CRMAP, as different SAA passages leave different imprints on the NICMOS detectors.

FGS 10756

Monitoring FGS1r Stability in Position Mode

This proposal gathers the data needed to monitor the FGS1r distortions and scale across its FOV. An astrometric field in M35 is observed 3 times per year, from Aug to December. Earlier versions of this proposal contained additional observartions from Jan to May. However, the ORIENT associated with those observations is not available under two-gyro operations. The particular field being observed in this proposal is from “orbit 1” of the FGS1r OFAD {proposal 8469}.

ACS/HRC 10752

Cycle 14 Focus Monitor

The focus of HST is measured primarily with ACS/HRC over full CVZ orbits to obtain accurate mean focus values via a well sampled breathing curve. Coma and astigmatism are also determined from the same data in order to further understand orbital effects on image quality and optical alignments. To monitor the stability of ACS to WFPC2 relative focii, we’ve carried over from previous focus monitor programs parallel observations taken with the two cameras at suitable orientations of previously observed targets, and interspersed them with the HRC CVZ visits.

ACS/SBC 10739

Internal Flat Field Stability

The stability of the CCD flat fields will be monitored using the calibration lamps and a sub-sample of the filter set. For the SBC imaging filters, differences in the low-frequency flat field structure with wavelength will be assessed. New high signal P-flats will be obtained for the SBC prisms.


CCD Hot Pixel Annealing

Hot pixel annealing will continue to be performed once every 4 weeks. The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C. This state will be held for approximately 6 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition. To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC. The HRC darks are taken in parallel with the WFC darks. The charge transfer efficiency {CTE} of the ACS CCD detectors declines as damage due to on-orbit radiation exposure accumulates. This degradation has been closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. We combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection. To this end, the CTE monitoring exposures have been moved into this proposal . All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages}. This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}.


ACS CCDs daily monitor

This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e-/DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period Oct, 2 2005- May, 29-2006. The second half of the program has a different proposal number: 10758.

ACS/WFC 10635

Galaxy Transformation as probed by Morphology and Velocity Fields of Distant Cluster Galaxies

We seek to obtain ACS imaging of four distant {0.3

ACS/WFC 10626

A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9

We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy clusters at 0.3 < z < 0.9 from the Red Sequence Cluster Survey {RCS}. An examination of the galaxian light in the brightest cluster galaxies, coupled with a statistical analysis of the strong-lensing properties of the sample, will allow us to contrain the evolution of both the baryonic and dark mass in cluster cores, over an unprecedented redshift range and sample size. In detail, we will use the high- resolution ACS images to measure the metric {10 kpc/h} luminosity and morphological disturbances around the brightest clusters galaxies, in order to calibrate their accretion history in comparison to recent detailed simulations of structure formation in cluster cores. These images will also yield a well-defined sample of arcs formed by strong lensing by these clusters; the frequency and detailed distribution {size, multiplicity, redshifts} of these strong lens systems sets strong constraints on the total mass content {and its structure} in the centers of the clusters. These data will also be invaluable in the study of the morphological evolution and properties of cluster galaxies over a significant redshift range. These analyses will be supported by extensive ongoing optical and near-infrared imaging, and optical spectroscopy at Magellan, VLT and Gemini telescopes, as well as host of smaller facilities.

ACS/HRC 10609

Sizes, Shapes, and SEDs: Searching for Mass Segregation in the Super Star Clusters of Nearby Starburst

We propose to investigate mass segregation and star cluster evolution and dissolution processes in Super Star Cluster {SSC} populations in a small sample of nearby starburst galaxies. ACS/HRC and NICMOS images of these nearby {d < 10 Mpc} starbursts can reveal evidence for mass segregation in the form of variations in size, shape, and color of the SSCs as a function of wavelength. The compactness of the cluster light profiles, and hence the stellar mass distributions, is a critical indicator of the likely fate of an SSC: long life and eventual evolution into a globular-like cluster, or dissolution. These observations will allow us to generate spectral energy distributions {SEDs} for a large sample of the SSCs at all ages and extinctions in each system. We will combine the SEDs with population synthesis models and existing ground- based spectra and Spitzer images to estimate ages, reddenings, and masses thus derive a more complete picture of the star-formation histories of the galaxies. For the brightest and most likely virialized among the SSCs we will also constrain their initial mass functions {IMFs} using high- resolution spectroscopy. Conclusions about IMFs from this technique require detailed information about the SSC concentration, light profiles, and virial status, which are only possible via ACS data. The proposed observations will provide an extensive and comprehensive data set for a large number of SSCs. By addressing the issues of mass segregation, evaporation, and destruction of SSC populations, the proposed observations will provide strong constraints on theories regarding the processes involved in the formation and evolution of SSCs and globular clusters. Given the dire predictions for the lifetime of HST, and its tremendous impact on the study of SSCs, we feel that the proposed observations not only are necessary and timely {even urgent} but will also be a fitting { and possibly final} addition to HST's legacy in the study of starburst SSCs.

ACS/HRC 10602

A Complete Multiplicity Survey of Galactic O2/O3/O3.5 Stars with ACS

Massive stars are preferentially formed in compact multiple systems and clusters and many of them remain spatially unresolved to date, even in our Galaxy. This has hindered the determination of the stellar upper mass limit. The lack of an accurate knowledge of the multiplicity of massive stars can also introduce biases in the calculation of the IMF at its high-mass end. We have recently used ACS/HRC to resolve HD 93129 A, the earliest O-type star known in the Galaxy, into a 55 mas binary. We propose here to extend that work into a complete multi-filter ACS imaging survey of all {20} known O2/O3/O3.5 Galactic stars to characterize the multiplicity of the most massive stars. The data will be combined with existing FGS observations to explore as large a parameter range as possible and to check for consistency. We will also derive the IMF of each system using a crowded-field photometry package and processing the data with CHORIZOS, a code that can derive stellar temperatures, extinctions, and extinction laws from multicolor photometry.

ACS/WFC 10596

AGNs with Intermediate-mass Black Holes: A Test of the Black Hole-Bulge Paradigm

The recent progress in the study of central black holes in galactic nuclei has led to a general consensus that supermassive {10^6-10^9 solar mass} black holes are closely connected with the formation and evolutionary history of large galaxies, especially their bulge component. Two outstanding issues, however, remain unresolved. Can central black holes form in the absence of a bulge? And does the mass function of central black holes extend below 10^6 solar masses? Intermediate-mass black holes {10^4-10^6 solar masses}, if they exist, may offer important clues to the nature of the seeds of supermassive black holes. In a first systematic search using the Sloan Digital Sky Survey, we have recently discovered 19 Type 1 AGNs with candidate intermediate-mass black holes that reside in low-luminosity, presumably late-type host galaxies. Follow-up observations with Keck indicate that these objects obey the low-mass extension of the well-known correlation between black hole mass and bulge stellar velocity dispersion. However, very little is known about the host galaxies themselves, including the crucial question of whether they have bulges or not. We propose to obtain ACS/WFC images of this unique sample of AGNs in order to investigate the detailed structural properties of the host galaxies. We are particularly keen to determine whether the hosts contain bulges, and if so, where they lie on the fundamental plane of spheroids compared to the bulges of supermassive black holes. We will also be able to measure an accurate optical luminosity for the AGN, which is an essential ingredient to improve the current mass estimates.

ACS/WFC 10592

An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These `luminous infrared galaxies’ {LIRGs} are primarily interacting or merging disk galaxies undergoing enhanced star formation and Active Galactic Nuclei {AGN} activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}. This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.

ACS/WFC 10586

The Rosetta Stone without a Distance: Hunting for Cepheids in the Primordial Galaxy I Zw 18

The Blue Compact Dwarf galaxy I Zw 18 is one of the most intriguing objects in the Local Universe. It has the lowest nebular metallicity of all known galaxies {Z=1/32 solar}. It has long been regarded as a possible example of a galaxy undergoing its first burst of star formation. However, its real evolutionary state continues to be controversial. The WFPC2 and NICMOS detection of AGB stars by our group and others suggested the presence of an underlying older population. However, deeper ACS observations by Izotov & Thuan {2004} recently failed to detect the signature of RGB stars. This was interpreted as confirmation that I Zw 18 is in fact a galaxy “in formation”, a local analog of primordial galaxies in the distant Universe. This result was widely reported in the international news media. However, an alternative possibility is that I Zw 18 is somewhat further away than previously believed, so that Red Giant Branch stars were too faint to detect. Quoted distances in the literature have ranged from 10 to 20 Mpc. We intend to resolve this controversy by direct determination of the distance to 1 Mpc accuracy using Cepheids. For this we request 12 visits of two orbits each, to execute at carefully planned intervals. We will obtain V and I band ACS/WFC photometry in each visit. The new data will be combined with archival data, but we show that the archival data by themselves are insufficient to achieve our science goals. The distance will allow us to place I Zw 18 into its proper place in the evolutionary sequence of galaxy formation.

ACS/HRC 10556

Neutral Gas at Redshift z=0.5

Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z>1.65. However, HST has now permitted us to discover 41 DLAs at z<1.65 in our previous surveys. Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe. But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe. Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime. Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7] which we estimate will permit us to discover another 41 DLAs. This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies. Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey.

ACS/HRC 10555

A Search for Satellites Around Kuiper Belt Objects Which Exhibit High Angular Momentum

We propose to use the HST to search for satellites around Kuiper Belt Objects which have large amplitude, fast rotational light curves. Large main belt asteroids with similar light curve characteristics have been found to have near an 80 percent companion rate. This is over an order of magnitude more than the companion rate of main belt asteroids in general. The satellites were probably formed during the process which imparted the high angular momentum on the primary object. To date five Kuiper Belt objects exhibit high angular momentum through their rotational light curves. Two of them have been observed with STIS on the HST and one was found to be a binary. We request three orbits with HST/ACS in order to obtain deep high resolution images of the other three Kuiper Belt objects that have large amplitudes and fast rotations. In addition, we request one orbit to reobserve the other KBO which didn’t have a satellite detection in order to obtain deeper and better resolution images than the first observations. Finding binaries is important not only to understand the processes which created the high angular momentum of the primary but also in determining the bulk densities and collisional histories of the objects.

ACS/HRC 10547

A SNAP Program to Obtain Complete Wavelength Coverage of Interstellar Extinction

We propose a SNAP program to obtain ACS/HRC spectra in the near-UV {PR200L} and near-IR {G800L} for a set of main sequence B stars with available IUE UV spectrophotometry, optical photometry, and 2MASS IR photometry. Together with these existing data, the new observations will provide complete photometric and spectrophotometric coverage from 1150 to 11000 A and enable us to produce complete extinction curves from the far-UV to the near-IR, with well- determined values of R{V}. The proposed set of 50 program sight lines includes the full range of interstellar extinction curve types and a wide range of color excesses. The new data will allow us to examine variability in the near-UV through near-IR spectral regions, including the UV-optical “knee” and the “Very Broad Structure.” We will examine the response of these features to different interstellar environments and their relationship to other curve features. These are largely unexplored aspects of extinction curves which will provide additional constraints on the properties of interstellar grains. The curves will be derived using stellar atmosphere models to represent the intrinsic spectral energy distributions of the program stars, eliminating the need to observe unreddened “standard stars.” This approach virtually eliminates “mismatch error”, allowing us to derive extinction curves with much higher precision than previously possible. In addition, the new spectra will provide higher S/N data for the peak of the 2175 A bump than previously available.

WFPC2 10537

Caught in the Act with HST — Active Jet Sculpting in the Young Preplanetary Nebulae IRAS 22036+5306

We have discovered an extended, highly-structured and bipolar nebula surrounding the post- AGB object IRAS22036+5306 {I22036}, in a Cycle 10 WFPC2 imaging survey of very young pre- planetary nebulae {PPNs}. Young PPNs like I22036, objects in rapid transition between the AGB and Planetary Nebulae {PN} phases, retain direct signatures, in the spatial character of their outflows, of the physical mechanisms which transform slowly expanding, round circumstellar AGB envelopes into highly aspherical PNs with fast-expanding elongated lobes along one or more axes. I22036 shows intriguing evidence for the presence of jets in the HST images, and VLA A-array maps show OH maser emission in a linear structure along the nebular axis. Our ground-based echelle H-alpha spectra show high-velocity blue-shifted absorption in a very broad {~2000 km/s} line profile, and mm-wave CO J=1-0 interferometric data show a bipolar molecular outflow. There are very few young PPNs like I22036 which show clear morphological & kinematical evidence of the presence of jets and their working surfaces, making it unquestionably a key object for understanding how jets can sculpt out bipolar lobes in a progenitor AGB star wind. Using ground-based long-slit spectroscopy with the Keck/ESI, we have partially spatially resolved the H-alpha emission in this object. We now propose to image I22036 in F658N, F631N, F606W and F814W in order to identify accurately the location and structure of the shocked gas, and its relation to the jets and their working surfaces. An important goal is to determine whether we can characterise the forward and reverse shocks near the heads of the knotty jets. The proposed HST imaging will help us to understand the spatio- kinematic structure of the outflowing gas in the bipolar lobes, and allow us to study the relationships between the important dynamical components of this nebula. Supporting ground- based observations such as Zeeman measurements of polarised OH masers with the VLBA to search for magnetic fields in I22036 are being pursued for testing magnetic-collimation models for jets in PPNs.


What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey

Essentially all planetary nebulae {PNs} are aspherical, whereas the mass-loss envelopes of AGB stars are strikingly spherical. Our previous SNAPshot surveys of a morphologically unbiased sample of pre-planetary nebulae {PPNs} — objects in transition between the AGB and PN evolutionary phases — show that roughly half our observed targets are resolved, with bipolar or multipolar morphologies. Spectroscopic observations of our sample confirm that these objects have not yet evolved into planetary nebulae. Thus, the transformation from spherical to aspherical geometries has already fully developed by the time these dying stars have become PPNs. Although our current studies have yielded exciting results, they are limited in two important ways — {1} the number of well-resolved objects is still small {18}, and the variety of morphologies observed relatively multitudinous, hence no clear trends can yet be established between morphology and other source properties {e.g., near-IR, far-IR colors, stellar spectral type, envelope mass}, and {2} the current samples are strongly biased towards small PPNs, as inferred from their low 60-to-25 micron flux ratios [R{60/25}<1]. However, the prototype of objects with R{60/25}>1, the Frosty Leo Nebula, has a puzzlingly large post-AGB age {almost 10^4 yr} and a fairly cool central star, very different from the expectations of single-star stellar evolutionary models. A proposed, but still speculative, hypothesis for such objects is that the slow evolution of the central star is due to backflow of material onto the mass-losing star, retarding its evolution towards the PN phase. This hypothesis has significant consequences for both stellar and nebular evolution. We therefore propose a survey of PPNs with R{60/25}>1 which is heavily weighted towards the discovery of such “stalled PPNs”. Supporting kinematic observations using long-slit optical spectroscopy {with the Keck}, millimeter and radio interferometric observations {with OVRO, VLA & VLBA} are being undertaken. The results from this survey {together with our previous work} will allow us to draw general conclusions about the complex mass-outflow processes affecting late stellar evolution, and will provide crucial input for theories of post-AGB stellar evolution. Our survey will produce an archival legacy of long-standing value for future studies of dying stars.

ACS/WFC 10523

The Halo Shape and Metallicity of Massive Spiral Galaxies

We propose to resolve the stellar populations of the halos of seven nearby, massive disk galaxies using a SNAP survey with WFC/ACS. These observations will provide star counts and color-magnitude diagrams 2-3 magnitudes below the tip of the Red Giant Branch along the two principal axes and one intermediate axis of each galaxy. We will measure the metallicity distribution functions and stellar density profiles from star counts down to very low average surface brightnesses, equivalent to ~31 V-mag per square arcsec. This proposal will create a unique sampling of galaxy halo properties, as our targets cover a range in galaxy mass, luminosity, inclination, and morphology. As function of these galaxy properties this survey will provide:- the first systematic measurement of radial light profiles and axial ratios of the diffuse stellar halos and outer disks of spiral galaxies- a comprehensive analysis of halo metallicity distributions as function of galaxy type and position within the galaxy- an unprecedented study of the stellar metallicity and age distribution in the outer disk regions where the disk truncations occur- the first comparative study of globular clusters and their field stellar populations We will use these fossil records of the galaxy assembly process to test halo formation models within the hierarchical galaxy formation scheme.

NIC1 10517

Imaging Astrometrically-Discovered Brown Dwarfs

We propose to image the astrometrically discovered companions of three M-dwarfs with NICMOS to more tightly constrain their masses and determine their stellar or sub-stellar natures. Each of these systems has been observed with a sensitive ground-based adaptive optics system and no companions have been detected. NICMOS results will eliminate an ambiguity in the astrometric mass measurements that arises because a companion that contributes significantly to the visible light reduces the motion of the center of light and mimics a small motion of the center of mass. In addition the astrometric measurements made with NICMOS will fix the scale of the system, distinguishing among possible orbits. Finally the color photometry will constrain the spectral types to within a couple of subtypes. When we measure the masses of astrophysical objects, we test and assist the development of the theoretical mass models. Models are based upon parameters such as age and metallicity. Determining the correct mass thus deepens our understanding of the fundamental physics of stars and substellar objects


Kuiper Belt Binaries: Probes of Early Solar System Evolution

Binaries in the Kuiper Belt are a scientific windfall: in them we have relatively fragile test particles which can be used as tracers of the early dynamical evolution of the outer Solar System. We propose a Snapshot program using the ACS/HRC that has a potential discovery efficiency an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. By more than doubling the number of observed objects in dynamically hot and cold subpopulations we will be able to answer, with statistical significance, the question of whether these groups differ in the abundance of binaries as a result of their particular dynamical paths into the Kuiper Belt. Today’s Kuiper Belt bears the imprints of the final stages of giant-planet building and migration; binaries may offer some of the best preserved evidence of that long-ago era.

ACS/WFC 10496

Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters

We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.

ACS/WFC 10494

Imaging the mass structure of distant lens galaxies

The surface brightness distribution of extended gravitationally lensed arcs and Einstein rings contains super-resolved information about the lensed object, and, more excitingly, about the smooth and clumpy mass distribution of the lens galaxies. The source and lens information can non-parametrically be separated, resulting in a direct “gravitational-mass image” of the inner mass-distribution of cosmologically-distant galaxies {Koopmans 2005}. With this goal in mind, we propose deep HST ACS-F555W/F814W and NICMOS-F160W imaging of 15 gravitational-lens systems with spatially resolved lensed sources, selected from the 17 new lens systems discovered by the Sloan Lens ACS Survey {Bolton et al. 2004}. Each system has been selected from the SDSS and confirmed in a time-efficient HST-ACS snapshot program {cycle-13}; they show highly-magnified arcs or Einstein rings, lensed by a massive early-type lens galaxy. High- fidelity multi-color HST images are required {not delivered by the 420-sec snapshot images} to isolate these lensed images {properly cleaned, dithered and extinction-corrected} from the lens galaxy surface brightness distribution, and apply our “gravitational-mass imaging” technique. The sample of galaxy mass distributions – determined through this method from the arcs and Einstein ring HST images – will be studied to: {i} measure the smooth mass distribution of the lens galaxies {Dark and luminous mass are separated using the HST images and the stellar M/L values derived from a joint stellar-dynamical analysis of each system}; {ii} quantify statistically and individually the incidence of mass-substructure {with or without obvious luminous counter- parts such as dwarf galaxies}. Since dark-matter substructure should be considerably more prevalent at higher redshift, both results provide a direct test of this prediction of the CDM hierarchical structure-formation model.

ACS/WFC 10491

A Snapshot Survey of the most massive clusters of galaxies

We propose a snapshot survey of a sample of 124 high X-ray luminosity clusters in the redshift range 0.3-0.7. Similarly luminous clusters at these redshifts frequently exhibit strong gravitational lensing. The proposed observations will provide important constraints on the nature of the cluster mass distributions and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. We acknowledge the broad community interest in this sample and waive our data rights for these observations.

NIC2 10173

Infrared Snapshots of 3CR Radio Galaxies

Radio galaxies are an important class of extragalactic objects: they are one of the most energetic astrophysical phenomena and they provide an exceptional probe of the evolving Universe, lying typically in high density regions but well-represented across a wide redshift range. In earlier Cycles we carried out extensive HST observations of the 3CR sources in order to acquire a complete and quantitative inventory of the structure, contents and evolution of these important objects. Amongst the results, we discovered new optical jets, dust lanes, face-on disks with optical jets, and revealed point-like nuclei whose properties support FR-I/BL Lac unified schemes. Here, we propose to obtain NICMOS infrared images of 3CR sources with z<0.3 as a major enhancement to an already superb dataset. We aim to deshroud dusty galaxies, study the underlying host galaxy free from the distorting effects of dust, locate hidden regions of star formation and establish the physical characteristics of the dust itself. We will measure frequency and spectral energy distributions of point-like nuclei, expected to be stronger and more prevalent in the IR, seek spectral turnovers in known synchrotron jets and find new jets. We will strongly test unified AGN schemes and merge these data with existing X-ray to radio observations. The resulting database will be an incredibly valuable resource to the astronomical community for years to come.


Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)


10005 – GSACQ(2,1,2) fails, search radius limit exceeded @308/2048z
GSACQ(2,1,2) at 308/20:44:21 failed due to Search Radius Limit Exceeded on FGS 1 at 20:48:07. One 486 status buffer message A07 (CT timed out waiting for data valid) was received. OBAD prior to GSACQ had total RSS attitude error correction of 7.17 arcseconds, within the search radius.

10006 – GSACQ(1,2,1) fine lock backup, scan step exceeded on FGS2 @309/0006z
GSACQ(1,2,1) at 309/00:02:44 ended in fine lock backup on FGS 1 due to scan step limit exceeded on FGS 2 at 00:06:05.

10007 – REacq(2,1,1) faileddue to search radius limit exceeded on FGS2@309/0928z
REacq(2,1,1) scheduled at 309/09:20:29 failed due to search radius limit exceeded on FGS 2 at 09:27:40. A ESB A05 (FGS Coarse Track failed – Search Radius Limit exceeded)was received.
OBAD1 showed errors of: V1=-17.55, V2=-2931.24, V3= -22.72, RSS=2931.38 OBAD2 showed errors of V1=-4.32, V2=-14.82, V3=-5.94, RSS=16.54 The Map at 09:27:55 showed errors of: V1=-1.13, V2=154.53, V3=-0.34, RSS=154.53

10008 – GSAcq(2,1,1) failed, search radius limit exceeded on FGS 2 @309/1237z
GSAcq (2,1,1) scheduled @ 309/12:32:27 failed due to search radius limit exceeded.
OBAD #1 – V1 -801.53, V2 -5795.11, V3 474.84, RSS 5869.51
OBAD #2 – V1 5.46, V2 0.25, V3 -0.73, RSS 5.52

10009 – REAcq(1,2,2) was not attempted @310/0124z
The OBAD at 310/01:06:02 failed. ESB 1902 (OBAD Failed Identification)
was received at 01:08:51. The OBAD showed errors of V1=-31166.14, V2=-5346.01, V3=-47158.95, RSS=56779.18.

10010 – OBAD Failed Identification @310/0108z
The OBAD at 310/01:06:02 failed. ESB 1902 (OBAD Failed Identification) was received at 01:08:51. The OBAD showed errors of V1=-31166.14, V2=-5346.01, V3=-47158.95, RSS=56779.18.



                           SCHEDULED      SUCCESSFUL      FAILURE TIMES
GSacq                 36                      34 
308/2048z(HSTAR 10005)
REacq                 08                       06 
309/0928z(HSTAR 10007)
OBAD with 
Maneuver    84                       83               310/0108z(HSTAR 


SpaceRef staff editor.