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Daily Report 3861
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT #3861 PERIOD COVERED: DOY 136 OBSERVATIONS SCHEDULED ACS/HRC 10165 Determination of orbits and colors for two new binaries in the Koronis asteroid family We propose to measure color and orbital properties of two asteroid binaries in the Koronis family discovered in our SNAP-9747 survey. The best previously studied asteroid binary system, Ida/Dactyl, is also in the Koronis family. Differential space weathering measured on the Ida and Dactyl surfaces has been a powerful constraint on models of satellite formation mechanisms and satellite survivability. HST offers the unique opportunity for similar measurements of these much smaller, main-belt binaries. The new satellites are believed to have formed through different collisional mechanisms than Ida/Dactyl. Further, with a set of 4 relative position measurements for each of the two systems, added to the discovery snapshots, we will determine and compare the densities of the primaries with Ida {a large, 31.5 km, asteroid with density 2.6+-0.5 g/cm^3, measured by the Galileo flyby}. In contrast, {17246} and {22899} are 4.5 km bodies that are likely to have been restructured since the family-forming event by subsequent collisions. As all are members of the same family, differences in density would constrain bulk composition and internal structure {e.g. shard vs. rubble-pile}. Hence, these measurements are likely to further elucidate the mechanisms for formation of satellites. ACS/HRC 10255 A Never Before Explored Phase Space: Resolving Close White Dwarf / Red Dwarf Binaries We propose an ACS Snapshot imaging survey to resolve a well-defined sample of highly probable white dwarf plus red dwarf close binaries. These candidates were selected from a search for white dwarfs with infrared excess from the 2MASS database. They represent unresolved systems {separations less than approximately 2" in the 2MASS images} and are distributed over the whole sky. Our HST+ACS observations will be sensitive to a separation range {1-20 AU} never before probed by any means. The proposed study will be the first empirical test of binary star parameters in the post-AGB phase, and cannot be accomplished from the ground. By resolving as few as 20 of our ~100 targets with HST, we will be able to characterize the distribution of orbital semi-major axes and secondary star masses. ACS/HRC 10377 ACS Earth Flats High signal sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently used by the pipeline and will provide a comparison with flats derived via other techniques: L-flats from stellar observations, sky flats from stacked GO observations, and internal flats using the calibration lamps. Weekly coronagraphic monitoring is required to assess the changing position of the spots. 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 programme will be for the entire lifetime of ACS. ACS/WFC 10187 Direct imaging of the progenitors of massive, core-collapse supernovae Modern supernovae searches in the nearby Universe are discovering large numbers of SNe which have massive star progenitors {Types II, Ib and Ic}. The extensive HST image archives of galaxies within ~20Mpc enables their individual bright stellar content to be resolved. As massive, evolved stars are the most luminous single objects in a galaxy, the progenitors of core-collapse SNe should be directly detectable on pre-explosion images. In our ongoing HST programme we have detected the first red supergiant progenitor of a normal type II supernova, shown that SN 1993J came from a binary system, and set direct mass-limits on three other type II supernovae progenitors. These discoveries are providing strong constraints on theoretical models of pre-supernova stellar evolution that predict which stars produce which type of supernovae. We request time to continue this successful project, and require ACS observations of future SNe which are discovered in galaxies closer than 20Mpc which have pre-explosion HST archive images available. These observations will allow the SNe to be precisely positioned on the pre-explosion frames with the required astrometric accuracy of around 0.05", and provide 3-colour photometry of the surrounding stellar populations for reddening estimations. The goal of this project is to directly identify the progenitor stars of core-collapse supernovae. We will compare the results to our own stellar evolutionary tracks in order to determine masses or restrictive mass-limits for the progenitors. ACS/WFC 10237 Low-Ionization BALs: Evolution or Orientation? We propose to test the hypothesis that Low-Ionization Broad Absorption Line Quasars {LoBALs} represent a special stage of quasar evolution: young quasars in systems with strong interaction and star-formation. We will carry out high resolution imaging using ACS/WFC and NICMOS to measure the properties of the host galaxies of four LoBAL quasars at z = 0.9 - 2.0 that show strong overlapping FeII absorption troughs. The ACS imaging will be carried out in the passband with the strongest BAL absorption, acting as a natural coronagraph. This results in a reduction of quasar light by a factor of 15 - 26 in these passbands, providing arguably the best view of the host galaxies of luminous, high-redshift quasars. This method allows efficient detection and detailed modeling of the host galaxy morphology in the rest-frame ultraviolet, which is most sensitive to star formation and galaxy interaction. We will also use NICMOS imaging to measure the rest- frame light from the host galaxy to probe the old stellar populations where the host galaxy is likely to be brighter. It has been suggested that LoBALs might not be explained simply as an orientation effect but rather as an early phase of quasar evolution. Such a phase is typically associated with large amounts of dust and gas, and young galaxies with strong star formation. With HST observations, we will study the color and morphology of the FeLoBAL quasar host galaxies, and measure the age of their dominant stellar populations. We will also measure the density of close companions, and, in particular, look for signs of ongoing or recent mergers. These measurements will be compared to those of control samples of normal quasars at similar redshift. If LoBALs are indeed young systems, then their host galaxies are expected to show stronger interactions and merger activity, younger stellar ages, and regions with strong star formation. If the LoBAL host galaxies show no significant difference from those of normal quasars, it will support the view that LoBAL quasars are not a distinct population and that all quasars have BAL outflows along some lines of sight. ACS/WFC 10417 Host Galaxies and Environments of the Most Massive Black Holes in the Early Universe The existence of luminous quasars with billion solar mass black holes at high redshift poses important questions about the relation between the formation and evolution of the earliest galaxies and quasars in the universe: how could these high- redshift black holes accrete matter so quickly and so efficiently? Is the quasar phase connected to the formation of galactic bulge in the earliest epoch? Was the black hole-bulge mass relation observed locally already established at high-redshift? We will use ACS/WFC to obtain rest-frame UV imaging of five quasars at z~4 with the highest estimated black hole mass, of the order 10 billion solar masses. The goal of the HST observation is to directly detect their host galaxies and to probe their galactic environment. These quasars are likely among the most massive and luminous host galaxies at high-redshift, providing ideal targets for direct detection. The rest-frame UV properties measured with HST will be combined with rest-frame optical, mid to far-IR oberservations of these quasars to measure the star-formation rate, to estimate the stellar age and mass of the host galaxy, and to probe the quasar/starburst connection, quasar triggering mechanism and relation between black hole and bulge formation at the highest possible redshift. One of the targets, PSS 2322+1944 {z=4.17}, is a gravitational lensed quasar with a nearly complete Einstein ring in CO emission, providing a unique opportunity to study the small scale structure of a high-redshift quasar host galaxy. ACS/WFC/NIC2 10189 PANS-Probing Acceleration Now with Supernovae Type Ia supernovae {SNe Ia} provide the most direct evidence for an accelerating Universe, a result widely attributed to dark energy. Using HST in Cycle 11 we extended the Hubble diagram with 6 of the 7 highest-redshift SNe Ia known, all at z1.25, providing conclusive evidence of an earlier epoch of cosmic deceleration. The full sample of 16 new SNe Ia match the cosmic concordance model and are inconsistent with a simple model of evolution or dust as alternatives to dark energy. Understanding dark energy may be the biggest current challenge to cosmology and particle physics. To understand the nature of dark energy, we seek to measure its two most fundamental properties: its evolution {i.e., dw/dz}, and its recent equation of state {i.e., w{z=0}}. SNe Ia at z1, beyond the reach of the ground but squarely within the reach of HST with ACS, are crucial to break the degeneracy in the measurements of these two basic aspects of dark energy. The SNe Ia we have discovered and measured with HST in Cycle 11, now double the precision of our knowledge of both properties. Here we propose to quadruple the sample of SNe Ia at z1 in the next two cycles, complementing on-going surveys from the ground at z1, and again doubling the precision of dark energy constraints. Should the current best fit model prove to be the correct one, the precision expected from the current proposal will suffice to rule out a cosmological constant at the 99% confidence level. Whatever the result, these objects will provide the basis with which to extend our empirical knowledge of this newly discovered and dominant component of the Universe, and will remain one of the most significant legacies of HST. In addition, our survey and follow-up data will greatly enhance the value of the archival data within the target Treasury fields for galaxy studies. NIC1 10143 Ultracool companions to the nearest L dwarfs We propose to conduct the most sensitive survey to date for low mass companions to nearby L dwarfs. We will use NICMOS to image targets drawn from a volume- complete sample of 70 L dwarfs within 20 parsecs. The combination of infrared imaging and proximity will allow us to search for T dwarf companions at separations as small as 1.6 AU. This is crucial, since no ultracool binaries are currently known with separations exceeding 15 AU. Only 10 dwarfs in this sample have previous HST observations primarily at optical wavelengths. With the increased sensitivity of our survey, we will provide the most stringent test to date of brown dwarf models which envisage formation as ejected stellar embryos. In addition, our observations will be capable of detecting binaries with mass ratios as low as 0.3, and will therefore also test the apparent preference for equal-mass ultracool binaries. Finally, our observations offer the best prospect to date of detecting companions significantly cooler than the coolest t dwarf currently known. NIC2 10418 Morphologies and Color Gradients of Galaxies with the Oldest Stellar Populations at High Redshifts We have isolated a sample of 9 luminous {~2L*} galaxies with the very oldest stellar populations at their respective redshifts. The galaxies have been found in radio- source fields chosen to be at the key redshifts z~1.5 and z~2.5, which allow the cleanest separation of old stellar populations from highly reddened starbursts with colors derived from standard filter combinations. Ground-based observations in excellent seeing and with adaptive optics of 3 of these galaxies indicate that all 3 are dominated by well relaxed disks of old stars, suggesting that the first large stellar systems to form in the universe were disks in which star formation proceeded extremely rapidly and efficiently. In order to test this conjecture, we are requesting NICMOS2 exposures of our sample to obtain high S/N imaging in the F160W filter to determine detailed morphologies of the old stellar population, coupled with either NICMOS2 F110W or ACS F814W exposures {depending on redshift} to determine color gradients and/or other systematic color variations that might provide clues to formation processes. NICMOS 8790 NICMOS Post-SAA calibration - CR Persistence Part 1. 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. WFPC2 10359 WFPC2 CYCLE 13 Standard Darks This dark calibration program obtains dark frames every week in order to provide data for the ongoing calibration of the CCD dark current rate, and to monitor and characterize the evolution of hot pixels. Over an extended period these data will also provide a monitor of radiation damage to the CCDs. WFPC2 10363 WFPC2 CYCLE 13 Intflat and Visflat Sweeps and Filter Rotation Anomaly Monitor Using intflat observations, this WFPC2 proposal is designed to monitor the pixel-to- pixel flatfield response and provide a linearity check. The intflat sequences, to be done once during the year, are similar to those from the Cycle 12 program 10075. The images will provide a backup database as well as allow monitoring of the gain ratios. The sweep is a complete set of internal flats, cycling through both shutter blades and both gains. The linearity test consists of a series of intflats in F555W, in each gain and each shutter. As in Cycle 12, we plan to continue to take extra visflat, intflat, and earthflat exposures to test the repeatability of filter wheel motions. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTARS: (None) COMPLETED OPS REQUEST: (None) COMPLETED OPS NOTES: (None) SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 6 6 FGS Reacq 10 10 FHST Update 12 12 LOSS of LOCK SIGNIFICANT EVENTS: (None) |
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