#1
|
|||
|
|||
Daily 3625
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3625 PERIOD COVERED: DOY 154 OBSERVATIONS SCHEDULED ACS 9472 A Snapshot Survey for Gravitational Lenses among z = 4.0 Quasars Over the last few years, the Sloan Digital Sky Survey has revolutionized the study of high-redshift quasars by discovering over 200 objects with redshift greater than 4.0, more than doubling the number known in this redshift interval. The sample includes eight of the ten highest redshift quasars known. We propose a snapshot imaging survey of a well-defined sample of 250 z 4.0 quasars in order to find objects which are gravitationally lensed. Lensing models including magnification bias predict that at least 4% of quasars in a flux-limited sample at z 4 will be multiply lensed. Therefore this survey should find of order 10 lensed quasars at high redshift; only one gravitationally lensed quasar is currently known at z 4. This survey will provide by far the best sample to date of high-redshift gravitational lenses. The observed fraction of lenses can put strong constraints on cosmological models, in particular on the cosmological constant Lambda. In addition, magnification bias can significantly bias estimates of the luminosity function of quasars and the evolution thereof; this work will constrain how important an effect this is, and thereby give us a better understanding of the evolution of quasars and black holes at early epochs, as well as constrain models for black hole formation. ACS/HRC/WFC 10048 Stability of the ACS CCD: Flat fielding, Photometry, Geometry This program will verify that the low frequency flat fielding, the photometry, and the geometric distortion are stable in time and across the field of view of the CCD detectors. A moderately crowded stellar field, located ~6' West of the center of the cluster 47 Tuc, is observed every three months with the WFC and HRC using the full suite of broad and narrow band filters. The same field has been observed during SMOV to derive low frequency corrections to the ground flats and to create a master catalogue of positions and magnitudes from dithered observations of the cluster. In Cycle 11, this field was observed again using single pointings at various roll angles. The positions and magnitudes of objects are used to monitor local and large scale variations in the plate scale and the sensitivity of the detectors. The Cycle 12 program will continue to monitor these effects and will derive an independent measure of the detector CTE. ACS/HRC/WFC 10060 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 9781 Galaxy Evolution in Action : The Detailed Morphology of Post-Starburst Galaxy If galaxies evolve morphologically, then some should be in transition between late and early types. One proposed evolutionary mechanism is a galaxy-galaxy merger, but evolved merger products are difficult to find. Fortunately, spectroscopic surveys have now uncovered large numbers of E+A galaxies, a class of objects whose post-starburst spectra, current lack of HI gas, and pressure-supported kinematics suggest that they are the missing panel that connects the "Toomre sequence" of merging spirals with normal ellipticals and S0s. Our first HST observations of five of these galaxies are intriguing. We find a considerable range of tidally disturbed morphologies, an "E+A" fundamental plane, significant differences among the color gradients within 1 kpc {~0.8''}, and populations of bright, blue globular clusters. These initial results are difficult to interpret, however, because they are drawn from a small sample of galaxies whose very blue overall colors may have selected a particular evolutionary path of E+As. Here we propose for ACS imaging of the remaining 15 E+As from the Las Campanas Redshift Survey to probe the full range of E+A properties. The proposed observations will allow us to 1} determine what fraction of the interactions that lead to E+As destroy all disk-like structures {and therefore necessarily lead to elliptical formation}, 2} measure the inner color gradients and constrain the spatial distribution of stars produced as gas sinks to the center during a merger, and 3} determine whether these interactions produce globular clusters in the required numbers to account for the increased specific frequency of clusters in early-type galaxies. ACS/WFC 9744 HST Imaging of Gravitational Lenses Gravitational lenses offer unique opportunities to study cosmology, dark matter, galactic structure, galaxy evolution and quasar host galaxies. They are also the only sample of galaxies selected based on their mass rather than their luminosity or surface brightness. While gravitational lenses can be discovered with ground-based optical and radio observations, converting them into astrophysical tools requires HST. We will obtain ACS/WFC V and I images and NICMOS H images of 21 new lenses never observed by HST and NICMOS H images of 16 lenses never observed by HST in the IR. As in previous cycles, we request that the data be made public immediately. ACS/WFC 9891 A snapshot survey of rich stellar clusters in the Large and Small Magellanic Clouds Rich stellar clusters are vital to a wide variety of astrophysical research, from stellar evolution studies to the formation and evolution of galaxies. In this context, it is important to understand how rich star clusters form and evolve. The cluster systems in the LMC and SMC are particularly important in achieving this, because they are the only systems which contain clusters at all stages of evolution while being close enough to be studied as fully resolved stellar populations - although in general this requires the capabilities of HST. We have recently investigated the structural evolution of LMC and SMC clusters using archival WFPC2 data, and demonstrated a dramatic trend in the sizes of these clusters with age. We have shown that this trend likely represents genuine structural evolution in these clusters, although it is not clear whether we are observing a dynamical process or the signature of changing formation conditions. This result has implications for all astronomical research involving massive stellar clusters. To develop this work further requires the extension of our two samples, so that they are statistically quantifiable. This will allow a number of key questions regarding the structural evolution trend to be answered. We propose a two-colour ACS/WFC SNAP survey of rich Magellanic Cloud clusters to achieve this aim. The unique resolution and sensitivity of ACS/WFC is required for success, because of the crowded nature of the targets. The SNAP data will have a large number of additional applications, both to globular cluster and Magellanic Cloud research. NIC1/NIC2/NIC3 8792 NICMOS Post-SAA calibration - CR Persistence Part 3 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 9845 NICMOS Confirmation of a Young Planetary-Mass Companion We have recently discovered a strong candidate for a planetary-mass {~10 Mjup} companion to a young Sun-like star, based on near-IR imaging and spectroscopy with the Keck and Subaru adaptive optics {AO} systems. While the ground-based data strongly suggest that the candidate has a very low effective temperature, and hence a very low mass, they are not definitive. We propose to obtain NICMOS coronagraphy to measure the companion's 1.9um water-band absorption. This feature is a distinct signature of very cool objects and is unobservable from the ground. The combined ground-based and space-based data set will determine whether the companion has a very low temperature, and hence if it is the lowest mass companion found to date by direct imaging. NICMOS 9485 Completing A Near-Infrared Search for Very Low Mass Companions to Stars within 10 pc of the Sun Most stars are fainter and less massive than the Sun. Nevertheless, our knowledge of very low mass {VLM} red dwarfs and their brown dwarf cousins is quite limited. Unknown are the true luminosity function {LF}, multiplicity fraction, mass function, and mass-luminosity relation for red and brown dwarfs, though they dominate the Galaxy in both numbers and total mass. The best way to constrain these relations is a search for faint companions to nearby stars. Such a search has several advantages over field surveys, including greater sensitivity to VLM objects and the availability of precise parallaxes from which luminosities and masses can be derived. We propose to complete our four-filter NICMOS snapshot search for companions to stars within 10 pc. With a 10 sigma detection limit of M_J ~ 20 at 10 pc, we can detect companions between 10 and 100 AU that are at least 9 mag fainter than the empirical end of the main sequence and at least 6.5 mag fainter than the brown dwarf Gl 229B. When completed, our search will be the largest, most sensitive, volume-limited search for VLM companions ever undertaken. Our four-filter search will permit unambiguous identification of VLM-companion candidates for follow-up observation. Together with IR speckle and deep imaging surveys, our program will firmly establish the LF for VLM companions at separations of 1-1000 AU and the multiplicity fraction of all stars within 10 pc. STIS/CCD 10018 CCD Dark Monitor-Part 2 Monitor the darks for the STIS CCD. STIS/CCD 10020 CCD Bias Monitor - Part 2 Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1, and 1x1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns. STIS/CCD/MA1/MA2 9962 Variable Interstellar Absorption toward HD 219188 --- Probing the Structure of an Interstellar Cloud Within the last 10 years, strong, narrow Na I absorption has appeared at v_SUN ~ -38 km s^-1 toward the halo star HD 219188; that absorption has continued to strengthen, by a factor 2--3, over the past three years. The line of sight appears to be moving into/through a relatively cold, quiescent intermediate velocity {IV} cloud, due to the 13 mas/year proper motion of HD 219188. We propose to monitor the continuing changes in the IV absorption toward HD 219188 over the next three years with STIS echelle spectra --- making use of the rich diagnostics provided by the UV lines of various neutral and singly ionized species to determine abundances/depletions and physical conditions {temperature, density, ionization} as functions of depth within the cloud. In addition to providing a unique view of the detailed structure of an interstellar cloud, these data will yield constraints on grain scattering parameters {from the variation of ionization with depth} and on any dependence of depletion on local density. WFPC2 10070 WFPC2 CYCLE 12 Supplemental Darks Part 2/3 This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. 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 08 08 FHST Update 13 13 LOSS of LOCK SIGNIFICANT EVENTS: Continuing Battery 4 Capacity Test. FGS 2 K16ACLIM change scheduled during window 155/12:30Z - 18:00Z while HST is outside SAA 1 contour and FGS 2 is assigned but not actively guiding (OR 17178 with attached script). TDRSS services during period 155/12:30Z - 18:00Z have been declared 'critical'. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Monitoring NASA Daily ISS Report | JimO | Space Station | 2 | June 1st 04 10:33 PM |
JimO Speaks on 'Daily Planet' re Hubble | JimO | Policy | 0 | February 11th 04 10:53 PM |
Spirit's daily activities schedule? | Matti Anttila | Policy | 0 | January 15th 04 08:39 AM |
best site for daily schedule of rover activity? | bob | History | 2 | January 5th 04 12:16 PM |
Investor's Business Daily: Rethinking NASA | dougk | Policy | 1 | August 28th 03 12:07 AM |