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Daily 3699
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3699 PERIOD COVERED: DOY 264 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 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/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/HRC/WFC 9728 Tracing the History of Cosmic Expansion to z~2 with Type Ia Supernovae Type Ia supernovae {SNe Ia} provide the only direct evidence for an accelerating universe, an extraordinary result that needs the most rigorous test. The case for cosmic acceleration rests on the observation that SNe Ia at z = 0.5 are about 0.25 mag fainter than they would be in a universe without acceleration. A powerful and straightforward way to assess the reliability of the SN Ia measurement and the conceptual framework of its interpretation is to look for cosmic deceleration at z 1. This would be a clear signature of a mixed dark-matter and dark-energy universe. Systematic errors in the SNe Ia result attributed to grey dust or cosmic evolution of the SN Ia peak luminosity would not show this change of sign. We have obtained a toehold on this putative ``epoch of deceleration'' with SN 1997ff at z = 1.7, and 3 more at z 1 from our Cycle 11 program, all found and followed by HST. However, this is too important a test to rest on just a few objects, anyone of which could be subject to a lensed line-of-sight or misidentification. Here we propose to extend our measurement with observations of twelve SNe Ia in the range 1.0 z 1.5 or 6 such SNe Ia and 1 ultradistant SN Ia at z = 2, that will be discovered as a byproduct from proposed Treasury and DD programs. These objects will provide a much firmer foundation for a conclusion that touches on important questions of fundamental physics. 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/WFC 10120 The Formation Histories and Dynamical Roles of X-ray Binaries in Globular Clusters Close binaries are fundamental to the dynamical stability and evolution of globular clusters, but large populations have been extremely difficult to identify. Chandra X-ray images provide a revolutionary resource, revealing a few to dozens of low-luminosity X-ray sources in every cluster deeply examined; our own Chandra programs uniformly study these ubiquitous X-ray sources {close binaries and their progeny} in 11 clusters. However, definitive understanding of the nature of the various X-ray subpopulations requires the identification of optical counterparts, and HST is the demonstrated key in these crowded environments. We thus propose a proven, efficient, and uniform, HST multicolor imaging program for optical identifications in 6 of our clusters with Chandra data on-hand, but which lack adequate optical images in the HST archive. The proposed ACS images will permit statistical classifications into the various subtypes: CVs, qLMXBs, BY Dra's/RS CVn's {and MSPs}. A unique aspect of our program is that our clusters span a range of physical properties such as central concentration, cluster size, and mass--essential ingredients in the formation, evolution, and dynamical roles of cluster binaries. Exploiting this range of properties, we have identified a relation that provides the first compelling link between the number of X-ray sources and the predicted stellar encounter frequency in globular cluster cores. But further progress in understanding the details implicit in this relationship {e.g., whether CVs and qLMXBs formed primarily via stellar encounters, while BY Dra's/RS CVn's are mainly primordial binaries} demands uniform optical identifications for multiple clusters, spanning the full range physical properties. 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/WFPC2 10227 Globular Cluster Systems of Giant, Post-Starburst Shell Ellipticals Mergers seem to have played a major role in determining the shapes and dynamics of elliptical galaxies. A few galactic mergers still occur and offer valuable clues to past evolutionary processes. Young globular clusters formed during mergers hold strong promise for age-dating such events, besides helping shed light on the cluster-formation process itself. With young globulars in ongoing mergers and ~0.5 Gyr old remnants now well studied {NGC 4038/39, 3256, 7252, and 3921}, we propose to observe 4 bona fide ellipticals featuring ripples, tidal tails as well as post-starburst spectra {E+A galaxies: strong Balmer absorption}, which are obvious candidates for having undergone a dissipative merger 1-4 Gyr ago. If the globulars formed during mergers are formed with a normal IMF, they should still be around in large numbers in intermediate-age systems. If that is indeed the case, it would constitute strong evidence in favor of the scenario in which metal-rich globulars in 'normal' ellipticals are formed in merging events. We plan to use these ACS observations to {1} measure high-accuracy {g-I error of 0.1 mag} colors for clusters as faint as the peak of the luminosity function {LF} of old globulars, {2} use these colors to separate first- and second-generation clusters, and {3} determine the LFs of the two kinds of clusters down to 1.5 mag past the LF peak for old globulars. Deep dithered g&I-band images form a crucial part of our observing strategy. When combined with previous HST studies of globulars in mergers, this study will yield about a dozen globular cluster systems with age estimates, enough to make meaningful statements about the influence of mergers in creating "red'', metal-rich globulars in giant E's and the evolution of the specific frequency of globular clusters during galactic mergers. FGS 9335 Masses of Pre-Main Sequence Binaries We propose to continue to map the orbits of young star binaries in the Taurus and Ophiuchus star forming regions. Our goal is to measure their masses dynamically. This is important because there are still no low mass young stars with reliably known masses so calculations of their evolution to the main sequence are uncalibrated. 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 10160 The nuclear scattering geometry of Seyfert galaxies Orientation-based unification schemes are now well-established as the basis for understanding the relationships between different classes of AGN. However, our recent study of the optical polarization properties of Seyfert 1 galaxies indicates that scattered light emerging from these objects often follows a different path to that in Seyfert 2's, indicating that the simplest unification geometry is incomplete. We have developed a generic scattering model for Seyfert nuclei which includes a compact, equatorial scattering region located within the circum-nuclear torus and the 'classic' polar scattering region outside it. We propose to test this model by using NICMOS to make NIR imaging observations that will allow us to isolate the two scattering regions within individual objects. 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 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. WFPC2 10362 WFPC2 Cycle 13 UV Earth Flats Monitor flat field stability. This proposal obtains sequences of earth streak flats to improve the quality of pipeline flat fields for the WFPC2 UV filter set. These Earth flats will complement the UV earth flat data obtained during cycles 8-12. WFPC2/ACS/HRC/WFC 10013 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. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTAR 9538: Second FHST Full Maneuver Update (U1,2FM) @ 264/20:52:14Z failed with Error Box results indicating "2 FAILED" for mnemonics QEBSTFG0, QEBSTFG1, and QEBSTFG2. GS Acquisition @ 264/20:55:28Z was successful. Under investigation. COMPLETED OPS REQs: None OPS NOTES EXECUTED: 1269-2 Enable Misc EPS Limits @ 264/22:40z SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 14 14 FGS Reacq 05 05 FHST Update 23 22 See Hstar # 9538 LOSS of LOCK SIGNIFICANT EVENTS: Set-up and execution of HST PSS 3.4 Development testing scheduled 265/11:00Z - 21:00Z with GDOC, HITT, and SOC using CCS "D" String with CCS Release xx (intentionally removed) and PRD xx (intentionally removed). The purpose of this testing is to verify the PSS 3.4 Simulator version can support Communications Module and SI FSW dumps. |
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