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Daily 3693
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3693 PERIOD COVERED: DOYs 254-256 OBSERVATIONS SCHEDULED ACS 9475 ACS coronagraphic survey for debris disks around nearby stars We propose a comprehensive imaging survey of nearby stars that will realize the full potential of the ACS coronagraph to map debris disks, the extrasolar analogs of our Kuiper Belt. Most debris disks are detected only by excess thermal emission at far-infrared wavelengths. Because they have a factor of 100 less dust cross section than the young debris disks around HR 4796A and beta Pic, they are undetectable by present techniques. In simulations of disk detectability, Kalas and Jewitt {1996} determined that detecting the scattered light from the disk requires at least two orders of magnitude of supression of the central PSF than is attainable from the ground. The ACS coronagraph finally provides this increase in sensitivity, surpassing the WFPC2 sensitivity to faint nebulosity near bright stars by at least three orders of magnitude. Mapping the debris around stars is particularly important for the indirect detection of planet-mass objects. Dynamical models have shown that unseen perturbers dynamically modify the radial, azimuthal and vertical structure of debris disks. These data will provide the critical high-resolution mapping of debris disks. 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. NIC/NIC3 10266 Origins of the Highly Ionized Gas toward the X-ray Bright BL Lac Object Mrk 421 The X-ray bright BL Lac object Mrk 421 is one of the small number of extragalactic objects for which it is possible to study the highly ionized gas in the ISM and Local Group using the full diagnostic power of UV, far-UV and X-ray observatories. High quality far-UV observations of OVI and other ions have been obtained by FUSE, whereas Chandra and XMM-Newton have provided X-ray measurements of extremely strong OVII and OVIII absorption at redshift zero. It has been proposed that the OVI, OVII, and OVIII originate together in the warm-hot intergalactic medium, of the kind predicted by numerical simulations to contain a substantial fraction of the baryons at z=0. However, the properties of the high-ion absorption are also consistent with an origin in an extended Galactic Corona. Data for other species such as SiIII, SiIV, and CIV will be essential to determine whether or not a Local Group WHIM filament has been detected. These species are not expected to be seen in a hot {T 10^6 K} medium and their detection at the same velocity as OVI would suggest that the OVI samples a different phase of the gas than the OVII and OVIII. We propose to obtain a high quality 7 km/s resolution STIS UV spectrum of Mrk 421 from 1150 to 1700 A. The STIS measurements of CII, CIV, SiIII, SiIV, and other species will allow us to evaluate the ionization conditions in the absorbing gas in the Galactic thick disk and in an anomalous high positive velocity absorption wing currently only traced by OVI and CIII. The ionic ratios among these species will provide critical tests of the ionization mechanisms affecting the OVI absorption. ACS/WFC/WFPC2 10265 The Formation History of Andromeda We propose deep observations of Andromeda's outer disk and giant tidal stream, to reconstruct their star formation histories. As the nearest giant galaxy, Andromeda offers the best testing ground for understanding galaxy formation and evolution. Given the dramatic increase in sensitivity offered by the ACS, we can now resolve stars on the old main sequence in the other giant spiral of the Local Group, and employ the same direct age diagnostics that have been used for decades in the study of Galactic globular clusters. In Cycle 11, we successfully observed a field in the Andromeda halo and constructed a deep color-magnitude diagram reaching well below the oldest main sequence turnoff. In Cycle 13, we propose to extend these observations to the outer disk and tidal stream of Andromeda, to constrain their star formation histories and compare them to that of the halo. The combined observations from these two programs will offer a dramatic advance in our understanding of the overall evolution of spiral galaxies. 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/WFC 10248 Current star formation in young, compact clusters in the Small Magellanic Cloud The Small Magellanic Cloud {SMC} offers a deep, resolved stellar population that leverages fundamental parameters {metallicity, dust content} with respect to the Milky Way and to its most studied counterpart, the LMC. Its subsolar metallicity makes it the best analog to the large majority of dwarf irregulars, and gives us the possibility to study star formation and evolution in an environment with the closest {available} resemblance to the early universe. Young, compact clusters are ideal laboratories to investigate how these fundamental differences affect star and cluster formation and evolution. We are therefore, proposing, to use ACS and NICMOS to perform a in depth study of the "resolved" stellar population in the four youngest compact clusters in the SMC. The observations, spanning the UV to the near-IR, will reach the subsolar domain, and will address the following fundamental questions: Does the IMF follow the universal Salpeter's law? Is mass segregation prevalent in the SMC clusters as in LMC clusters? Is on-going star formation present, where and how? What is the role of massive star feedback? The four proposed clusters span an age range from 3-20 Myr, and sample spatially different regions of the SMC. The synergy with NICMOS will permit full characterization of existing pre main sequence stars, if detected. This proposal is part of a coordinated HST and ground-based study of the stellar history and star formation processes in the SMC. NIC/NIC3 10226 The NICMOS Grism Parallel Survey We propose to continue managing the NICMOS pure parallel program. Based on our experience, we are well prepared to make optimal use of the parallel opportunities. The improved sensitivity and efficiency of our observations will substantially increase the number of line-emitting galaxies detected. As our previous work has demonstrated, the most frequently detected line is Halpha at 0.7z1.9, which provides an excellent measure of current star formation rate. We will also detect star-forming and active galaxies in other redshift ranges using other emission lines. The grism observations will produce by far the best available Halpha luminosity functions over the crucial--but poorly observed--redshift range where galaxies appear to have assembled most of their stellar mass. This key process of galaxy evolution needs to be studied with IR data; we found that observations at shorter wavelengths appear to have missed a large fraction of the star-formation in galaxies, due to dust reddening. We will also obtain deep F110W and F160W images, to examine the space densities and morphologies of faint red galaxies. In addition to carrying out the public parallels, we will make the fully reduced and calibrated images and spectra available on-line, with some ground-based data for the deepest parallel fields included. ACS/WFC 10217 The ACS Fornax Cluster Survey The two rich clusters nearest to the Milky Way, and the only large collections of early-type galaxies within ~ 25 Mpc, are the Virgo and Fornax Clusters. We propose to exploit the exceptional imaging capabilities of the ACS/WFC to carry out the most comprehensive imaging survey to date of early-type galaxies in Fornax: the ACS Fornax Cluster Survey. Deep ACS/WFC images -- in the F475W {g'} and F850LP {z'} bands -- will be acquired for 44 E, S0, dE, dE, N and dS0 cluster members. In Cycle 11, we initiated a similar program targeting early-type galaxies in the Virgo Cluster {the ACS Virgo Cluster Survey; GO-9401}. Our proposed survey of Fornax would yield an extraordinary dataset which would complement that already in hand for Virgo, and allow a definitive study of the role played by environment in the structure, formation and evolution of early-type galaxies and their globular cluster systems, nuclei, stellar populations, dust content, nuclear morphologies and merger histories. It would also be a community resource for years to come and, together with the ACS Virgo Cluster Survey, constitute one of the lasting legacies of HST. ACS/HRC/NIC1/WFC 10190 The Star Formation History and Metallicity Evolution of M33: A Comprehensive Study of Disk Evolution We will obtain deep, panchromatic imaging photometry of stellar populations in four fields ranging from 0.5 to 4 scale lengths across the disk of the Local Group spiral M33. The observations are designed to detect the oldest main-sequence turnoffs in three outer disk fields, and to reach the crowding limit in the innermost field. We will combine the photometry data with information we already have in-hand on abundances from stars and H II regions in M33 to derive the star formation history and metallicity evolution of the M33 disk. The information from our four fields will allow us to obtain {1} the ages of the oldest disk stars and the radial variation of their ages; {2} the radial variation of the star formation history and its nature {e.g., constant, declining, or bursting}; and {3} the metallicity distribution in each field and the time evolution of the metallicity gradient. Our team, an experienced mix of photometrists, spectroscopists, and galaxy evolution theorists, will use the results from this program to construct a comprehensive chemo-dynamical model for the M33 disk. This detailed study of M33 will be a key in developing an understanding of the formation and evolution of disks that can be applied to studies of disks at both low and high redshift, and will also yield a wealth of information on stellar populations, chemical evolution, and star clusters that will be of great value to future investigators. ACS/HRC 10185 When does Bipolarity Impose itself on the Extreme Mass Outflows from AGB Stars? An ACS SNAPshot Survey Essentially all well-characterized preplanetary nebulae {PPNe} -- objects in transition between the AGB and planetary nebula evolutionary phases - are bipolar, whereas the mass-loss envelopes of AGB stars are strikingly spherical. In order to understand the processes leading to bipolar mass-ejection, we need to know at what stage of stellar evolution does bipolarity in the mass-loss first manifest itself? Our previous SNAPshot surveys of a PPNe sample {with ACS & NICMOS} show that roughly half our targets observed are resolved, with well-defined bipolar or multipolar morphologies. Spectroscopic surveys 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 preplanetary nebulae. From this new and surprising result, we hypothesize that the transformation to bipolarity begins during the very late AGB phase, and happens very quickly, just before, or as the stars are evolving off the AGB. We propose to test this hypothesis quantitatively, through a SNAPshot imaging survey of very evolved AGB stars which we believe are nascent preplanetary nebulae; with our target list being drawn from published lists of AGB stars with detected heavy mass-loss {from millimeter-wave observations}. This survey is crucial for determining how and when the bipolar geometry asserts itself. 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 onset of bipolar mass-ejection during 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/SBC 10183 A Deep Far-UV Search for the Interacting Binary Population in M80 We propose to carry out a deep, far-ultraviolet {FUV}, time-resolved survey for cataclysmic variables {CVs} and other dynamically-formed objects in the globular cluster {GC} M80. This will include a search for FUV counterparts to the 17 Chandra sources in our field of view, which include 2 LMXBs and 5 X-ray selected CV candidates. Our goal is to confirm these sources as interacting binaries and find any additional CVs below the Chandra detection limit. We will achieve this with 6 orbits of FUV imaging with the ACS/SB, plus one additional orbit of NUV imaging with ACS/HRC. Since crowding is not a problem in the FUV, this will yield time-resolved FUV photometry of all blue objects in the cluster core. Our CV census will be both deep enough to be essentially complete and ``broad'' enough to involve all of the following CV characteristics: {1} UV brightness; {2} blue FUV spectral shape; {3} strong CIV and HeII emission; {4} short time-scale {$sim$ minutes} variability {flickering, WD spin}; {6} intermediate time-scale {$sim$ hours} variability {orbital variations}; {7} long time-scale {$sim$ weeks} variability {dwarf nova eruptions}. We will thus uncover the interacting binary population in M80. In addition, our survey will detect numerous blue stragglers and hot white dwarfs, as well as any other blue objects in the central regions of this cluster. ACS/HRC 10182 Towards a Comprehensive Understanding of Type Ia Supernovae: The Necessity of UV Observations Type Ia supernovae {SNe Ia} are very important to many diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology which led to the discovery of dark energy and the accelerating Universe. However, the utility of SNe Ia as cosmological probes depends on the degree of our understanding of SN Ia physics, and various systematic effects such as cosmic chemical evolution. At present, the progenitors of SNe Ia and the exact explosion mechanisms are still poorly understood, as are evolutionary effects on SN Ia peak luminosities. Since early-time UV spectra and light curves of nearby SNe Ia can directly address these questions, we propose an approach consisting of two observational components: {1} Detailed studies of two very bright, young, nearby SNe Ia with HST UV spectroscopy at 13 epochs within the first 1.5 months after discovery; and {2} studies of correlations with luminosity for five somewhat more distant Hubble-flow SNe Ia, for which relative luminosities can be determined with precision, using 8 epochs of HST UV spectroscopy and/or broad-band imaging. The HST data, along with extensive ground-based optical to near-IR observations, will be analyzed with state-of-the-art models to probe SN Ia explosion physics and constrain the nature of the progenitors. The results will form the basis for the next phase of precision cosmology measurements using SNe Ia, allowing us to more fully capitalize on the substantial past {and future} investments of time made with HST in observations of high-redshift SNe Ia. NIC2 10176 Coronagraphic Survey for Giant Planets Around Nearby Young Stars A systematic imaging search for extra-solar Jovian planets is now possible thanks to recent progress in identifying "young stars near Earth". For most of the proposed young {~ 30 Myrs} and nearby {~ 60 pc} targets, we can detect a few Jupiter-mass planets as close as a few tens of AUs from the primary stars. This represents the first time that potential analogs of our solar system - that is planetary systems with giant planets having semi-major axes comparable to those of the four giant planets of the Solar System - come within the grasp of existing instrumentation. Our proposed targets have not been observed for planets with the Hubble Space Telescope previously. Considering the very successful earlier NICMOS observations of low mass brown dwarfs and planetary disks among members of the TW Hydrae Association, a fair fraction of our targets should also turn out to posses low mass brown dwarfs, giant planets, or dusty planetary disks because our targets are similar to {or even better than} the TW Hydrae stars in terms of youth and proximity to Earth. Should HST time be awarded and planetary mass candidates be found, proper motion follow-up of candidate planets will be done with ground-based AOs. NIC2 10169 Star Formation in Luminous Infrared Galaxies: giant HII Regions and Super Star Clusters Luminous Infrared Galaxies {LIRGs, LIR = 10^11-10^12Lsol} and Ultraluminous Infrared Galaxies {LIR10^12Lsol} account for approximately 75% of all the galaxies detected in the mid-infrared in the redshift range z=0-1.5. In the local universe it is found that LIRGs are predominantly powered by intense star formation {SF}. However, the physical conditions and processes governing such dramatic activity over scales of tens to a few hundred parsecs are poorly known. In the last decade HST has been playing a significant role, mainly with the discovery of super star clusters {SSCs}, and more recently, giant HII regions. Based on observations of a few LIRGs, we found that these giant HII regions and associated SSCs appear to be more common in LIRGs than in normal galaxies, and may dominate the star formation activity in LIRGs. A larger sample is required to address fundamental questions. We propose an HST/NICMOS targeted campaign of a volume limited sample {v5200km/s} of 24 LIRGs. This proposal will probe the role of giant HII regions in the overall energetics of the current star formation, their relation to SSCs, and the dependence of star formation properties on other parameters of LIRGs. Such detailed knowledge of the SF properties of LIRGs in the local universe is essential for understanding galaxies at high redshift. ACS/WFC 10152 A Snapshot Survey of a Complete Sample of X-ray Luminous Galaxy Clusters from Redshift 0.3 to 0.7 We propose a public, uniform imaging survey of a well-studied, complete, and homogeneous sample of X-ray clusters. The sample of 73 clusters spans the redshift range between 0.3-0.7. The samples spans almost 2 orders of magnitude of X-ray luminosity, where half of the sample has X-ray luminosities greater than 10^44 erg/s {0.5-2.0 keV}. These snapshots will be used to obtain a fair census of the morphology of cluster galaxies in the cores of clusters, to detect radial and tangential arc candidates, to detect optical jet candidates, and to provide an approximate estimate of the shear signal of the clusters themselves, and potentially an assessment of the contribution of large scale structure to lensing shear. ACS/HRC 10130 Systemic Proper Motions of the Magellanic Clouds from Astrometry with ACS: II. Second Epoch Images We request second epoch observations with ACS of Magellanic Cloud fields centered on the 40 quasars in the LMC and SMC for which we have first epoch Cycle 11 data. The new data will determine the systemic proper motion of the Clouds. An extensive astrometric analysis of the first epoch data shows that follow-up observations with a two year baseline will allow us to measure the proper motion of the clouds to within 0.022 mas/year in each of the two orthogonal directions {assuming that we can image 25 quasars, i.e., with a realistic Snapshot Program completion rate}. The best weighted combination of all previous measurements has a seven times larger error than what we expect. We will determine the proper motion of the clouds with 2% accuracy. When combined with HI data for the Magellanic Stream this will constrain both the mass distribution in the Galactic Halo and theoretical models for the origin of the Magellanic Stream. Previous measurements are too crude for such constraints. Our data will provide by far the most accurate proper motion measurement for any Milky Way satellite. FGS 10106 An Astrometric Calibration of the Cepheid Period-Luminosity Relation We propose to measure the parallaxes of 10 Galactic Cepheid variables. When these parallaxes {with 1-sigma precisions of 10% or better} are added to our recent HST FGS parallax determination of delta Cep {Benedict et al 2002}, we anticipate determining the Period-Luminosity relation zero point with a 0.03 mag precision. In addition to permitting the test of assumptions that enter into other Cepheid distance determination techniques, this calibration will reintroduce Galactic Cepheids as a fundamental step in the extragalactic distance scale ladder. A Period-Luminosity relation derived from solar metallicity Cepheids can be applied directly to extragalactic solar metallicity Cepheids, removing the need to bridge with the Large Magellanic Cloud and its associated metallicity complications. WFPC2 10071 WFPC2 CYCLE 12 Supplemental Darks Part 3/3 This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. ACS/HRC/WFC 10061 CCD Daily Monitor This program consists of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. This programme will be executed once a day for the entire lifetime of ACS. ACS/WFC 10043 External CTE Monitor Monitor CTE changes during cycle 11. Determine CTE. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) None COMPLETED OPS REQs: None OPS NOTES EXECUTED: None SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 32 32 FGS Reacq 19 19 FHST Update 54 54 LOSS of LOCK SIGNIFICANT EVENTS: None |
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