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Daily 3709
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3709 PERIOD COVERED: DOY 278 OBSERVATIONS SCHEDULED ACS/HRC 10180 Ultracompact Blue Dwarfs: Galaxy Formation in the Local Universe? Recent observations suggest that very low-mass galaxies in the local universe are still in the process of formation. To investigate this issue we propose to obtain deep ACS HRC images in the U, V and I bands of a sample of 11 "ultracompact" blue dwarf galaxies {UCBDs} identified in the Sloan Digital Sky Survey. These objects are nearby {z 0.009}, actively star-forming, and have extremely small angular and physical sizes {d 6" and D 1 kpc}. They also tend to reside in voids. Our WFPC2 images of the prototype object of this class, POX 186, reveal this tiny object to have a highly disturbed morphlogy indicative of a recent {within 10^8 yr} collision between two small {~ 100 pc} clumps of stars that could represent the long-sought building blocks predicted by the Press-Schechter model of hierarchical galaxy formation. This collision has also triggered the formation of a "super" star cluster {SSC} at the object's core that may be the progenitor of a globular cluster. POX 186 thus appears to be a very small dwarf galaxy in the process of formation. This exciting discovery strongly motivates HST imaging of a full sample of UCBDs in order to determine if they have morphologies similar to POX 186. HST images are essential for resolving the structure of these objects, including establishing the presence of SSCs. HST also offers the only way to determine their morphologies in the near UV. The spectra of the objects available from the SDSS will also allow us to measure their star formation rates, dust content and metallicities. In addition to potentially providing the first direct evidence of Press-Schechter building blocks, these data could yield insight into the relationship between galaxy and globular cluster formation, and will serve as a test of the recent "downsizing" model of galaxy formation in which the least massive objects are the last to form. ACS/HRC 10199 The Most Massive Galaxies in the Universe: Double Trouble? We are proposing an HST snapshot survey of 70 objects with velocity dispersion larger than 350 km/s, selected from the Sloan Digital Sky Survey. Potentially this sample contains the most massive galaxies in the Universe. Some of these objects may be superpositions; HST imaging is the key to determining if they are single and massive or if they are two objects in projection. The objects which HST imaging shows to be single objects are interesting because they potentially harbor the most massive black holes, and because their existence places strong constraints on galaxy formation models. When combined with ground based data already in hand, the objects which HST imaging shows are superpositions provide valuable information about interaction rates of early-type galaxies as well as their dust content. They also constrain the allowed parameter space for models of binary gravitational lenses {such models are currently invoked to explain discrepancies in the distribution of lensed image flux ratios and separations}. 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 10135 Unveiling the Progenitors and Physics of Cosmic Explosions GRBs and XRFs are clearly highly asymmetric explosions and require a long-lived power source {central engine}. In contrast, nearby core-collapse events are essentially spherical explosions. However, the failure of spherical neutrino driven collapses has led to the idea that asymmetric energy release is essential for the explosion. The recent finding of a Type Ic SN in GRB 030329, the association of the low energy event GRB 980425 with SN 1998bw, the theoretical development discussed above and the rise of collapsar models make it timely to consider whether all these explosions contain engines. Given the uncertainties in theoretical modeling it is clear that observations are needed to guide models. A priori there is little reason to expect connection between the ultra-relativistic jet that powers the GRB and the explosive nucleosynthesis of the ~0.5 solar masses of Nickel-56 that powers the accompanying supernova. We propose a comprehensive program of ACS photometric searches {and measurements} for SNe associated with GRBs and XRFs. In concert, we will undertake ground-based spectroscopy to determine velocity widths, and measure engine parameters from pan-chromatic afterglow observations. Our goal is to produce a comprehensive database of engine and SN physical parameters against which theoretical modeling will be guided. ACS/WFC 10174 Dark-matter halos and evolution of high-z early-type galaxies Gravitational lensing and stellar dynamics provide two complementary methods to determine the mass distribution and evolution of luminous and dark-matter in early-type {E/S0} galaxies. The combined study of stellar dynamics and gravitational lensing allows one to break degeneracies inherent to each method separately, providing a clean probe of the internal structure of massive galaxies. Since most lens galaxies are at redshifts z=0.1-1.0, they also provide the required look-back time to study their structural and stellar-population evolution. We recently analyzed 5 E/S0 lens galaxies between z=0.5 and 1.0, combining exquisite Hubble Space Telescope imaging data with kinematic data from ground-based Keck spectroscopy, placing the first precise constraints on the dark-matter mass fraction and its inner slope beyond the local Universe. To expand the sample to ~30 systems -- required to study potential trends and evolution in the E/S0 mass profiles -- we propose to target the 49 E/S0 lens-galaxy candidates discovered by Bolton et al. {2004} from the Sloan Digital Sky Survey {SDSS}. With the average lens rate being 40% and some systems having a lensing probability close to unity, we expect to discover ~20 strong gravitational lenses from the sample. This will triple the current sample of 9 E/S0 systems, with data in hand. With the sample of 30 systems, we will be able to determine the average slope of the dark-matter and total mass profile of E/S0 galaxies to 10% and 4% accuracy, respectively. If present, we can simultaneously detect 10% evolution in the total mass slope with 95% confidence. This will provide unprecedented constraints on E/S0 galaxies beyond the local Universe and allow a stringent test of their formation scenarios and the standard cosmological model. ACS/WFC 10216 Co-evolution of spheroids and black holes The masses of the giant black holes in galaxies are correlated with the luminosities, masses, and velocity dispersions of their host spheroids. This empirical connection of phenomena on widely different scales {from sub-parsec to kiloparsec} suggests that the evolution of a galaxy and its central black hole are closely linked. We propose to test various unified formation models, by measuring the cosmic evolution of the black hole/spheroid relations, back to z=0.37 {a lookback time of 4 Gyrs}. We will obtain 1-orbit ACS images of a sample of 20 Seyfert 1 galaxies, for which we already have extensive new ground-based measures of the black hole masses and the stellar velocity dispersions. HST resolution is required for accurate measurement of the nonstellar AGN continuum, and the luminosity and effective radius of the bulge of each host galaxy. This will complete the set of observables needed to map the co-evolution of spheroids and black-holes. The proposed sample is the minimum required to make the first measure of the black hole mass/bulge correlation and of the fundamental plane for active galaxies outside the local Universe. 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. NIC1/Spacecraft 10382 NICMOS Focus Stability The purpose of this activity is to determine if the best focus. This program will execute in one month intervals starting about 1 month after the last execution of proposal 9994 {the previous focus monitoring program}. The program starts with a focus sweep using only the NIC1 camera {visit 11}. The following observation is with the NIC2 camera {visit 12} after about 45 days. This pattern is repeated throughout the period except for Feb 15 where also the NIC3 camera is used. In total this will result in 9 orbits. Notice that VISIT #1 #2 refers to visits for #1 sequential visit number for a given camera #2 camera in question visit 32 is therefore the third visit for camera 2. 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. WFPC2 10068 WFPC2 CYCLE 12 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 10170 Atmospheric Variability 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; 7885: Hammel, Karkoschka, and Marley; 8680: Hammel, Rages, Lockwood, and Marley; and 8634: Rages, Hammel, Lockwood, Marley, and McKay} 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 Telescope 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. 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 10 10 FGS Reacq 5 5 FHST Update 20 20 LOSS of LOCK SIGNIFICANT EVENTS: None |
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