SpaceRef

SpaceRef


NASA Hubble Space Telescope Daily Report #3933

Status Report From: Space Telescope Science Institute
Posted: Monday, August 29, 2005

image

HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT # 3933

PERIOD COVERED: UT August 26-28, 2005 (DOY 238-240)

OBSERVATIONS SCHEDULED

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.

WFPC2/ACS/WFC 10697

The Host Galaxy and Environment of the Binary Quasar J1643+3156

We will observe the binary quasar J1643+3156 of type O2R located at a redshift of 0.586 and with a separation of 15 kpc {2.3 arcsec} to simultaneously compare the environment and host galaxies of a radio-loud and -quiet quasar.

ACS/HRC 10627

A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae

We propose an ACS/HRC snapshot survey of 50 post-AGB sources, objects which have evolved from the AGB but may or may not become planetary nebulae {PNe}. This survey will complement existing HST images of proto-planetary nebulae {PPNe} and PNe in addressing circumstellar envelope morphology as a function of: 1} the progenitor star mass; 2} the chemical composition; and 3} evolutionary stage. We will connect the observed diversity of nebualar shapes with the main physical and chemical conditions characterizing post-AGB objects, to identify the mechanism that breaks the symmetry of AGB mass loss. To our knowledge, no previous HST projects have been specifically designed to address this issue. From our database of 360 post-AGB candidates, we have selected approximately 50 targets, none of which have been or are being observed with HST, to sample different central star masses, chemical compositions, and evolutionary stages, uniformly across the sky. These new data will also provide important constraints to a quantitative analysis of Spitzer Space Telescope {SST} observations planned for a similar sample of objects. We will model the HST images and SST spectra using our axisymmetric dust code 2-Dust, to derive dust density distributions, pole to equator density ratios, dust shell masses, inclination angles as well as dust composition.

ACS/HRC 10623

HST Optical Snapshot Survey of Intermediate Redshift Ultraluminous Infrared Galaxies

Ultraluminous infrared galaxies {ULIGs} are commonly believed to be a transitory phase in the evolution of disk galaxy mergers into QSOs. However, a recently reported discrepancy between the morphological and structural properties of z < 0.13 ULIGs and z = 0.12-0.25 QSOs with M{V} < -23.5 has cast doubt on their evolutionary connection. We propose an ACS snapshot survey of a sample of 39 ULIGs with z = 0.35-1.0. These galaxies are the best suited for comparison with luminous z=0.12-0.25 QSOs because {1} they are at larger lookback times than local ULIGs, and thus are likely representative of the systems that evolve into lower redshift luminous QSOs, {2} they have luminosities comparable to luminous QSOs and, {3} they are selected in a manner that biases the sample towards harboring imbedded AGN, and thus are the most likely precursors to optical QSOs. High resolution HST ACS images will allow a determination of galaxy morphology and reveal the presence of bright AGN. The 2-D profile of each galaxy will be modeled using GALFIT, with the AGN comprising one component of the fit where applicable to better characterize the underlying galaxy. Fundamental parameters {effective radius and surface brightness, and F814W-band magnitude} of the underlying galaxy will thus be measured and compared with the host galaxies of the luminous QSO sample. This imaging campaign will consume a modest amount of HST time, but will provide for the first time a statistically significant view of ULIGs at look-back times of 30-65% the age of the universe, and sufficient resolution and sensitivity to conduct a meaningful comparison with z=0.12-0.25 QSOs, as well as with local {z < 0.3} IRAS-detected and distant {z > 2} SCUBA-detected ULIGs.

FGS 10614

Internal Structure and Figures of Binary Asteroids

The goal of this proposal is to obtain very important information on the internal structure of a number of asteroids, and insight on the gravitational reaccumulation-process after a catastrophic disruptive collision. High resolutions observations with the HST/FGS interferometer are proposed to obtain high precision data for the topographic shape and size of a number of selected asteroids. Here we focus on objects with satellites, hence with known masses, so that the bulk density and porosity will be derived in the most accurate manner. This will yield plausible estimates on the internal properties of the objects, test wether they are close or not to figures of equilibrium {in terms of shape and adimensional rotational frequency}, and provide estimates of their relative density. The HST/FGS in interferometric mode is an ideal facility to carry out this program.

FGS 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric elements {perturbation orbit semi-major axis and inclination} of extra-solar planets orbiting six stars. These companions were originally detected by radial velocity techniques. We have demonstrated that FGS astrometry of even a short segment of reflex motion, when combined with extensive radial velocity information, can yield useful inclination information {McArthur et al. 2004}, allowing us to determine companion masses. Extrasolar planet masses assist in two ongoing research frontiers. First, they provide useful boundary conditions for models of planetary formation and evolution of planetary systems. Second, knowing that a star in fact has a plantary mass companion, increases the value of that system to future extrasolar planet observation missions such as SIM PlanetQuest, TPF, and GAIA.

ACS/HRC 10607

Probing Circumstellar and Interstellar Dust with Scattered-Light Echoes

Scattered-light echoes are one of the most powerful and efficient probes of the structure and composition of dust in circumstellar and interstellar {ISM} environments. Observations of light echoes provide exact three-dimensional positions of dust while constraining its density, grain- size and chemical make-up. Furthermore, echoes can be used as distance indicators via polarization measurements. We propose to take deep, high-resolution ACS/HRC images of five supernovae {SNe}. Two of these, SNe 1991T and 1998bu, have known circumstellar echoes that have only recently become fully resolvable with HST, and therefore require new observations. Only four echo-producing SNe are currently known, and in an attempt to increase this sample, we will also observe SNe 1999bw, 2002hh, and 2004dj. All three SNe are strong candidates for producing echoes from circumstellar and ISM dust, but only at angular sizes that HST can resolve. With these observations, we will use light echoes to their full advantage, to study {1} the mass-loss histories of Type II and Ia SN progenitors, {2} the contributions of these SNe and their progenitors to the dust content of their galaxies, {3} the structure of gas and stars in the ISM of external galaxies, and {4} we will independently measure the distance to the host galaxies, including a member of the Virgo cluster, and M96, a Type Ia cosmological distance- scale calibrator.

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/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.

ACS/HRC 10545

Icy planetoids of the outer solar system

Early HST studies of satellites of Kuiper belt object focussed on the 50-200 km objects that were the largest known at the time. In the past 3 years we have discovered a population of much more rare and much larger {500-2000+ km} icy planetoids in the Kuiper belt. These objects are the largest and brightest known in the Kuiper belt and, in the era when we now know of more than 1000 Kuiper belt objects, these few planetoids are likely to be the focus of much of the research on physical properties of the outer solar system for years to come. We are currently engaged in an intensive program involving Spitzer, Keck, and other telescopes to study the physical and dynamical properties of this new population. HST is uniquely capable of addressing one parameter fundamental to completing the physical picture of these planetoids: the existence and size of any satellites. The detection and characterization of satellites to these large planetoids would allow us to address unique issues critical to the formation and evolution of the outer solar system, including the measurement of densities, internal properties, sizes and shapes of these objects, the study of binary formation as a function of primary size, and the context of the Pluto-Charon binary. For these bright objects, a satellite search takes less than a full orbit, allowing the opportunity for a new project on UV spectroscopy of the planetoids to piggyback at no added time cost. This poorly explored spectral range has the potential to show unique signatures of trapped gasses, cosmochemically important ices, and complex organic materials.

WFPC2 10534

Active Atmospheres on Uranus and Neptune

We propose Snapshot observations of Uranus and Neptune to monitor changes in their atmospheres on time scales of weeks, months, and years. Uranus is rapidly approaching equinox in 2007, with another 4 degrees of latitude becoming visible every year. Recent HST observations during this epoch {including 6818: Hammel, Lockwood, and Rages; 8680: Hammel, Rages, Lockwood, and Marley; 8634: Rages, Hammel, Lockwood, Marley, and McKay; and 10170: Rages, Hammel, Lockwood, and Marley} have revealed strongly wavelength-dependent latitudinal structure and the presence of numerous visible-wavelength cloud features in the northern hemisphere. Long-term ground-based observations {Lockwood and Thompson 1999} show seasonal brightness changes whose origins are not well understood. Recent near-IR images of Neptune obtained using adaptive optics on the Keck Telesccope together with images from our Cycle 9 Snapshot program {8634} show a general increase in activity at south temperate latitudes as well as the possible development of another Great Dark Spot. Further Snapshot observations of these two dynamic planets will elucidate the nature of long-term changes in their zonal atmospheric bands and clarify the processes of formation, evolution, and dissipation of discrete albedo features.

ACS/WFC/NIC3/WFPC2 10530

Probing Evolution And Reionization Spectroscopically {PEARS}

While imaging with HST has gone deep enough to probe the highest redshifts, e.g. the GOODS survey and the Ultra Deep Field, spectroscopic identifications have not kept up. We propose an ACS grism survey to get slitless spectra of all sources in a wide survey region {8 ACS fields} up to z =27.0 magnitude, and an ultradeep field in the HUDF reaching sources up to z =28 magnitude. The PEARS survey will: {1} Find and spectrocopically confirm all galaxies between z=4-7. {2} Probe the reionization epoch by robustly determining the luminosity function of galaxies and low luminosity AGNs at z = 4 - 6. With known redshifts, we can get a local measure of star formation and ionization rate in case reionization is inhomogeneous. {3} Study galaxy formation and evolution by finding galaxies in a contiguous redshift range between 4 < z < 7, and black hole evolution through a census of low-luminosity AGNs. {4} Get a robust census of galaxies with old stellar populations at 1 < z < 2.5, invaluable for checking consistency with heirarchical models of galaxy formation. Fitting these galaxies' spectra will yield age and metallicity estimates. {5} Study star-formation and galaxy assembly at its peak at 1< z < 2 by identifying emission lines in star-forming galaxies, old populations showing the 4000A break, and any combination of the two. {6} Constrain faint white dwarfs in the Galactic halo and thus measure their contribution to the dark matter halo. {7} Derive spectro-photometric redshifts by using the grism spectra along with broadband data. This will be the deepest unbiased spectroscopy yet, and will enhance the value of the multiwavelength data in UDF and the GOODS fields to the astronomical community. To this end we will deliver reduced spectra to the HST archives.

ACS/WFC 10497

Cepheid Calibrations of the Luminosity of Two Reliable Type Ia Supernovae and a Re- determination of the Hubble Constant

We propose to determine the luminosity of two type Ia supernovae {SNe Ia}, 1995al in NGC 3021 and SN 2002fk in NGC 1309, by observing Cepheids in their spiral hosts. Modern CCD photometry yields an extremely tight Hubble diagram for SNe Ia with a precisely determined intercept {i.e., Delta H_0/H_0}. Yet, the measurement of the true Hubble constant via SNe Ia is limited by the calibration derived from problematic and unreliable SN data. Most of the SNe Ia calibrated by HST to date are significantly compromised by the systematics of photographic photometry, high reddening and SN peculiarity, and by the photometric anomolies associated with WFPC2. The extended reach of ACS now provides opportunities to more reliably calibrate SNe Ia and H_0. Our Cepheid calibration of a reliable SN Ia dataset, SN 1994ae, using ACS in Cycle 11 resulted in a 15% increase in H_0 from the value derived by the HST SN Ia Calibration Program. Yet, there remains a terribly small sample of reliable SN Ia data sets on which to base such a crucial cosmological result. SN 1995al and SN 2002fk are two of the best observed SNe Ia both with little reddening. They provide two opportunities to use ACS for placing the calibration of H_0 via SN Ia on firmer footing and potentially improve its precision.

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/HRC/WFC 10487

A Search for Debris Disks in the Coeval Beta Pictoris Moving Group

Resolved observations of debris disks present us with the opportunity of studying planetary evolution in other solar systems. We propose to search for debris disks in the Beta Pictoris moving group {8-20 Myrs, 10-50 pc away} , which provides a coeval sample of multiple spectral types, and it has already produced two magnificent resolved debris disks: AU Mic and Beta Pic. Such coeval sample will provide us with a snapshop of the crucial time in disk evolution in which the disk makes the transition from optically thick to optically thin, and it will be useful to study the stellar mass dependence of the disk evolution.

ACS/HRC 10473

Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons

We propose to image the rings and small inner satellites of Uranus using the High Resolution Channel of the ACS. The revolutionary capabilities of the ACS will allow us to address a variety of important questions relating to ring properties and ring-moon interactions. Observations at a range of wavelengths and phase angles will reveal the opposition surges of these rings and moons, providing information on color and surface structure. Measurements of the ring in front of the planet will provide complementary information on optical depth; any variations of optical depth with wavelength will reveal the rings' poorly-constrained population of embedded dust. The rings of Uranus are closing rapidly as the planet approaches equinox in 2007, an event that takes place only every 42 years. Using this opportunity, our observations will be repeated at different solar and terrestrial tilt angles; this sequence of images will be particularly valuable for constraining the physical thickness and packing density of the rings. We will place particular emphasis on the rotational variations of the Epsilon Ring, whose radial width {and therefore its packing density} varies by a factor of five. In addition, deep exposures through the CLEAR filter will enable us to detect and recover 4-5 km moons in or near the ring system. Dynamicists invoke numerous such moons to "shepherd" the many sharp ring boundaries, so this will serve as a definitive test of the theory.

NIC1/NIC2 10410

Anisotropy and obscuration in the near-nuclear regions of powerful radio galaxies

Despite the success of the orientation-based unified schemes for powerful radio sources, we are still far from understanding the distribution of obscuring material in the near-nuclear regions of such sources, and how this distribution evolves with radio power. Following on from our highly successful Cycle 7 pilot observations of Cygnus A, we propose a near-IR polarimetric survey of a complete sample of powerful radio galaxies in order map the near-nuclear illumination cones, and investigate the distribution of obscuring material on a 0.1 to 1kpc scale. In particular, the observations will allow us to test the "receding torus model'' which predicts that the opening angles of the illumination cones are smaller in low redshift/low power radio galaxies than in their high redshift/high power counterparts.We will also investigate whether AGN- and jet-driven outflows have a substantial effect on distribution of obscuring material by "hollowing out'' the quasar illumination cones in the more powerful sources. Finally, by using our polarization maps to search for signs of intrinsic anisotropy in the near-IR continuum within the cones, we will investigate the geometry of the near-IR continuum emitting regions close to the quasar nuclei. These observations are not only crucial for our understanding of radio source unification, but also provide key information about the effects of AGN-induced outflows on the ISM of the host galaxies.

ACS/HRC/WFC 10389

ACS CCDs daily monitor - Cycle 13 - Part 2

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 program will be for the entire lifetime of ACS.

ACS/HRC/WFC/WFPC2 10384

Focus Monitor

The focus of HST is measured from WFPC2/PC and ACS/HRC images of stars. Multiple exposures are taken in parallel over an orbit to determine the influence of breathing on the derived mean focus. Observations are taken of clusters with suitable orientations to ensure stars appear in all fields.

ACS/WFC 10352

A Study of the Physics of Extended Relativistic X-ray Jets, Discovered in our Chandra Survey

We will measure the changing flow speeds, magnetic fields, and energy fluxes in well-resolved quasar jets found in our short-exposure Chandra survey by combining new, deep Chandra data with radio and optical imaging. We will image each jet with sufficient sensitivity to estimate beaming factors and magnetic fields in several distinct regions, and so map the variations in these parameters down the jets. HST observations will help diagnose the role of synchrotron emission in the overall SED, and may reveal condensations on scales less than 0.1 arcsec.

ACS/HRC 10238

The nature of quasar host galaxies: combining ACS imaging and VLT Integral Field Spectroscopy.

We propose to perform ACS/F606W imaging of a complete sample of 29 quasar host galaxies {0.08< z <0.34}. The spatial resolving power of the ACS HRC, in combination with the acquisition of empirical PSFs and advanced deconvolution techniques, will allow to study in detail structures on scales of a few tens of parsecs, and to access the inner regions of the host galaxies, even in the presence of bright nuclei. We demonstrate that combining deep spectroscopy with high resolution imaging in stable PSF conditions definitely constitutes the solution to characterize the complex physical properties of quasar host galaxies, from their outer regions to the inner 0.1 kpc, where most of the information on the interplay between quasars and their hosts is hidden. We propose to combine new ACS images with existing Integral Field VLT Spectra. We will map the stellar and gas velocity fields in 2D, constrain the mass models, derive the radial host M/L ratios, map and characterize the stellar populations and the ionization state of the gas.

ACS/WFC 10235

Dark vs. luminous matter in the CenA/M83 galaxy complex

The distribution of dark vs. luminous matter on scales of 0.1-1.0 Mpc remains poorly understood. For a nearby group, the total mass can be determined from the radius of "the zero-velocity surface", which separates the group from the general Hubble flow. This new method requires the measurement of accurate distances and radial velocities of galaxies around the group, but gives total mass estimates independent of assumptions about the state of relaxation or orbital characteristics. The mass pertains to the group at the full scale to which it is bound. Upon application in several nearest groups, the method yields mass estimates in agreement with the sum of the virial masses of subcomponents. However, the typical total M/L ratio for the nearby groups of ~30 Mo/Lo implies a local mean density of matter which is only 1/7 the canonical global density . The nearby complex of galaxies around Cen A and M83 resembles our Local Group by the dumb-bell concentration of objects around a pair of dominant galaxies. Accurate distances have been acquired recently for ~20 group members by the TRGB method using HST. We will measure TRGB distances to the 17 remaining galaxies in the region. These observations will constrain the dynamical state of the halo surrounding the nearest giant E-galaxy Cen A, providing a comparison with the halos of the nearest spirals.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS: 9928 - Guide Star Acquisition Failed, Search Radius Limit Exceeded on FGS 3 @ 239/07:39:16z

GSacq3,1,3 at 239/07:39:16 failed due to Search Radius Limit Exceeded on FGS 3. Full Maneuver Updates prior to the acquisition had nominal errors of -23.685, 12.042, -0.184 for the first update, and 0.688, 0.461, -0.609 for the second update. FHST map at 08:23 showed nominal attitude errors of -10.165, -8.616, -7.968.

COMPLETED OPS REQUEST:

  • 17527-0 - Null GENSLEWS for proposal 10460 - slots 1, 2, and 3 @ 238/1542z
  • 17528-0 - Modify Control Law Gains for T2G Mode @ 241/00:09:18z
  • 17522-5 - Transition to TGS Operations @ 241/02:22:54z
  • 17434-0 - Contingency: Bring +D SPA Trim Relay Back On-Line (CANCELLED)
  • 17530-2 - Load Safemode Support Files for TGS Operations @ 241/05:50:46z

COMPLETED OPS NOTES: (None)

                                 SCHEDULED     SUCCESSFUL    FAILURE TIMES
FGS 
Gsacq                     28                     27               239/07:39:16z
FGS Reacq                     18                     18
FHST Update                   42                     42
OBAD with Manuver          02                     02
LOSS of LOCK

SIGNIFICANT EVENTS:

Transition to TGS operations @ 241/02:16:34z

// end //

More status reports and news releases or top stories.

Please follow SpaceRef on Twitter and Like us on Facebook.