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Daily 3728
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3728 PERIOD COVERED: DOY 306 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 10272 A Snapshot Survey of the Sites of Recent, Nearby Supernovae During the past few years, robotic {or nearly robotic} searches for supernovae {SNe}, most notably our Lick Observatory Supernova Search {LOSS}, have found hundreds of SNe, many of them in quite nearby galaxies {cz 4000 km/s}. Most of the objects were discovered before maximum brightness, and have follow-up photometry and spectroscopy; they include some of the best-studied SNe to date. We propose to conduct a snapshot imaging survey of the sites of some of these nearby objects, to obtain late-time photometry that {through the shape of the light and color curves} will help reveal the origin of their lingering energy. The images will also provide high-resolution information on the local environment of SNe that are far superior to what we can procure from the ground. For example, we will obtain color-color and color-magnitude diagrams of stars in these SN sites, to determine their progenitor masses and constraints on the reddening. Recovery of the SNe in the new HST images will also allow us to actually pinpoint their progenitor stars in cases where pre-explosion images exist in the HST archive. Use of ACS rather than WFPC2 will make our snapshot survey even more valuable than our Cycle 9 survey. This Proposal is complementary to our Cycle 13 archival proposal, in which we outline a plan for using existing HST images to glean information about SN environments. ACS/HRC/WFC 10367 ACS CCDs daily monitor- cycle 13 - part 1 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 10101 The Region of the Hydrogen-Burning Limit in Omega Centauri and 47 Tucanae We propose a photometric study of the lower main sequences of Omega Cen and 47 Tuc, down to the region of the H-burning limit, which the deeper faintness limit of ACS will allow us to reach. For the faintest stars, proper-motion separation of cluster from field is essential; hence we include Cycle 13 observations. The resulting color--magnitude diagrams {CMDs} and luminosity functions {LFs} will allow study of stars in a mass regime and metallicity that have never been accessible before, and will serve as an important check on theories of the structure of low-mass stars. These are the 2nd-epoch observations. 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/WFC 10369 ACS internal CTE monitor The charge transfer efficiency {CTE} of the ACS CCD detectors will decline as damage due to on-orbit radiation exposure accumulates. This degradation will be closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. 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/WFC/NIC/NIC3/WFPC2 10246 The HST survey of the Orion Nebula Cluster We propose a Treasury Program of 104 HST orbits to perform the definitive study of the Orion Nebula Cluster, the Rosetta stone of star formation. We will cover with unprecedented sensitivity {23-25 mag}, dynamic range {~12 mag}, spatial resolution {50mas}, and simultaneous spectral coverage {5 bands} a ~450 square arcmin field centered on the Trapezium stars. This represents a tremendous gain over the shallow WFC1 study made in 1991 with the aberrated HST on an area ~15 times smaller. We maximize the HST observing efficiency using ACS/WFC and WFPC2 in parallel with two opposite roll angles, to cover the same total field. We will assemble the richest, most accurate and unbiased HR diagram for pre-main-sequence objects ever made. Combined with the optical spectroscopy already available for ~1000 sources and new deep near-IR imaging and spectroscopy {that we propose as Joint HST-NOAO observations}, we will be able to attack and possibly solve the most compelling questions on stellar evolution: the calibration of pre-main-sequence evolutionary tracks, mass segration and the variation of the initial mass function in different environments, the evolution of mass accretion rates vs. age and environment, disk dissipation in environments dominated by hard vs. soft-UV radiation, stellar multiplicity vs. disk fraction. In addition, we expect to discover and classify an unknown, but substantial, population of pre-Main Sequence binaries, low mass stars and brown dwarfs down to ~10 MJup. This is also the best possible way to discover dark silhouette disks in the outskirts of the Orion Nebula and study their evolutionary status through multicolor imaging. This program is timely and extremely well leveraged to other programs targeting Orion: the ACS H-alpha survey of the Orion Nebula, the recently completed 850ks ultradeep Chandra survey, the large GTO programs to be performed with SIRTF, plus the availability of 2MASS and various deep JHK surveys of the core recently done with 8m class telescopes. 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. 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. 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 10177 Solar Systems In Formation: A NICMOS Coronagraphic Survey of Protoplanetary and Debris Disks Until recently, despite decades of concerted effort applied to understanding the formation processes that gave birth to our solar system, the detailed morphology of circumstellar material that must eventually form planets has been virtually impossible to discern. The advent of high contrast, coronagraphic imaging as implemented with the instruments aboard HST has dramatically enhanced our understanding of natal planetary system formation. Even so, only a handful of evolved disks {~ 1 Myr and older} have been imaged and spatially resolved in light scattered from their constituent grains. To elucidate the physical processes and properties in potentially planet-forming circumstellar disks, and to understand the nature and evolution of their grains, a larger spatially resolved and photometrically reliable sample of such systems must be observed. Thus, we propose a highly sensitive circumstellar disk imaging survey of a well-defined and carefully selected sample of YSOs {1-10 Myr T Tau and HAeBe stars} and { app 10 Myr} main sequence stars, to probe the posited epoch of planetary system formation, and to provide this critically needed imagery. Our resolved images will shed light on the spatial distributions of the dust in these thermally emissive disks. In combination with their long wavelength SEDs the physical properties of the grains will be discerned, or constrained by our photometrically accurate surface brightness sensitivity limits for faint disks which elude detection. Our sample builds on the success of the exploratory GTO 7233 program, using two-roll per orbit PSF-subtracted NICMOS coronagraphy to provide the highest detection sensitivity to the smallest disks around bright stars which can be imaged with HST. Our sample will discriminate between proposed evolutionary scenarios while providing a legacy of cataloged morphologies for interpreting mid- and far-IR SEDs that the recently launched Spitzer Space Telescope will deliver. 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 in the event of complete failure of the visflat lamp 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.) None COMPLETED OPS REQs: None OPS NOTES EXECUTED: None SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 13 13 FGS Reacq 3 3 FHST Update 18 18 LOSS of LOCK SIGNIFICANT EVENTS: None |
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