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HST Daily Report #3396
HUBBLE SPACE TELESCOPE
DAILY REPORT # 3396 PERIOD COVERED: DOY 182 OBSERVATIONS SCHEDULED STIS 9359 The Old Star CS 31082-001, the Age of the Universe, and the Nature of the r-process We propose to observe the newly discovered r-process-element enhanced star, CS 31082-001 {Fe/H ~ -2.9}, in order to determine abundances of the heaviest stable elements, using absorption lines that are only reachable in the near UV. This star is the only halo star for which a uranium detection has been reported, and for which the U/Th chronometer has been used to specify an age limit. In order to improve the accuracy of the age determination from U/Th we require abundance estimates of the daughter nuclides --Pb & Bi-- for which only upper limits have been obtained from ground-based observations. Such estimates will provide crucial constraints on the initial production ratio of U/Th, resulting in a more strict lower limit on the age of this star's progenitor, hence on the age of the Universe. Measurements of 3rd-peak neutron-capture elements, such as Pt, Os, Ir, and Au, all with lines in the 2400-3100 Angstrom range, will expand our knowledge of element synthesis in the early Galaxy. Our recent ESO-VLT data indicate that the neutron-capture elements in this star exhibit different enhancements as compared with the previously known `` r-process star'' CS 22892-052, an apparent anomaly that must be resolved. CS 31082-001 is the ideal HST target in its class -- it is 4-times brighter than CS 22892-052, and less affected by molecular line blending. Consequently, these HST data will become the reference in all future studies of similar stars. STIS/FUV 9412 The Physical Parameters of the Hottest, Most Luminous Stars as a Function of Metallicity We have obtained excellent, new ground-based blue optical and HAlpha spectra of a sample of very early-type stars in the Magellanic Clouds in order to measure their physical properties, for comparison with the extensive data that exists for higher-metallicity Galactic stars. Our aim is to understand how effective temperatures depend upon metallicity {necessary in determining IMFs}, and to explore the astrophysically interesting regime of stars of extreme temperatures, masses, and luminosities. In order to do this, we need to measure the stellar wind terminal velocities for our stars, necessary to constrain the stellar models. These can only be measured with STIS/FUV on HST. In addition, we will obtain higher spatial resolution data on the HAlpha line for stars for which nebular contamination is significant in our ground-based data. We also include several R136 stars with excellent STIS/CCD data but which lack UV line measures. These new HST data will provide important information about the strengths of stellar winds at extreme luminosities and the calibration of the Wind Momentum- Luminosity Relationship at lower metallicities. This proposal was highly rated in Cycle 9, but only 4 snapshots were obtained. We have completed the analysis of these plus additional data from the archives, but need spectra of the remaining objects if we are to answer the questions we pose. SNAP/STIS 9434 A SNAPSHOT Survey of the Hot Interstellar Medium We propose to obtain SNAPSHOT STIS echelle observations of key tracers of hot interstellar gas {CIV, NV and SiIV} for selected FUSE Team OVI survey targets with known UV fluxes. By taking advantage of the SNAPSHOT observing mode we will efficiently obtain a large number of spectra suitable for the study of the highly ionized hot component of the interstellar medium {ISM}. Our goals are to explore the physical conditions in and distribution of such gas, as well as to explore the nature of the interfaces between the hot ISM and the other interstellar gas phases. Using inter--comparisons of the various ionic ratios for CIV, NV, OVI and SiIV, we will be able to discriminate between the various models for the production of the highly ionized gas in the Galactic ISM. The survey will also enable detailed studies of regions already known to contain hot gas through X-ray emission measurements {e.g., SNRs and radio loops}. The proposed SNAPSHOT observations will extend our previous Cycle 9 survey {which was compromised by the STIS side 1 failure}, and should roughly double the number of stars for which high quality STIS observations of the important hot gas tracers are available, enabling us to derive a truly global view of the hot ISM. ACS 9462 Systemic and Internal Proper Motions of the Magellanic Clouds from Astrometry with ACS We request first epoch observations with ACS of Magellanic Cloud fields centered on background quasars. Second epoch observations will be requested ~ 5 years later to allow the measurement of the systemic and internal proper motions of the Clouds with error ~0.05 mas/year. These motions are of fundamental importance. The systemic motions of the LMC and SMC probe the gravitational potential of the dark halo. The internal proper motion due to rotation can be exploited to yield a rotational parallax distance to the LMC; the first time that this will be done for any galaxy. This is particularly important for the LMC because of its crucial role in the extragalctic distance ladder. Previous measurements of the proper motion of the LMC yield a systemic component ranging from 1.4 mas/year to 3.4 mas/year {differing by several times the quoted errors}, with no useful determination of the internal motions. The main problem with measurements of the proper motion of the LMC has been the lack of a sample of background quasars to use as reference frame. We have recently been able to identify a sample of 54 quasars behind the Magellanic Clouds from their variability characteristics in the MACHO database. With this sample and the advent of ACS an accurate proper motion measurement has become possible for the very first time. 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. 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. WFPC2 9595 WFPC2 CYCLE 11 SUPPLEMENTAL DARKS pt3/3 This dark calibration program obtains 3 dark frames every day to provide data for monitoring and characterizing the evolution of hot pixels. STIS 9606 CCD Dark Monitor-Part 2 Monitor the darks for the STIS CCD. STIS 9608 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 9615 Cycle 11 MAMA Dark Monitor This test performs the routine monitoring of the MAMA detector dark noise. This proposal will provide the primary means of checking on health of the MAMA detectors systems through frequent monitoring of the background count rate. The purpose is to look for evidence of change in dark indicative of detector problem developing. STIS 9633 STIS parallel archive proposal - Nearby Galaxies - Imaging and Spectroscopy Using parallel opportunities with STIS which were not allocated by the TAC, we propose to obtain deep STIS imagery with both the Clear {50CCD} and Long-Pass {F28X50LP} filters in order to make color-magnitude diagrams and luminosity functions for nearby galaxies. For local group galaxies, we also include G750L slitless spectroscopy to search for e.g., Carbon stars, late M giants and S-type stars. This survey will be useful to study the star formation histories, chemical evolution, and distances to these galaxies. These data will be placed immediately into the Hubble Data Archive. ACS 9657 ACS Internal Flat Field Stability The flat field stability and characterization obtained during the ground calibration and SMOV phases will be tested and verified through a sub-sample of the filter set. Only internal exposures with the calibration lamps will be required. ACS 9674 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. STIS 9708 STIS Pure Parallel Imaging Program: Cycle 11 This is the default archival pure parallel program for STIS during cycle 11. WFPC2 9709 POMS Test Proposal: WFII parallel archive proposal This is the generic target version of the WFPC2 Archival Pure Parallel program. The program will be used to take parallel images of random areas of the sky, following the recommendations of the 2002 Parallels Working Group. WFPC2 9710 POMS Test Proposal: WFII backup parallel archive proposal This is a POMS test proposal designed to simulate scientific plans. ACS/HRC 9805 OGLE-TR-56b: The Most Interesting Transiting Planet Our team has recently succeeded in confirming spectroscopically the discovery of the first extrasolar giant planet found in a transit search: OGLE-TR-56b. Its main parameters a mass = 0.9 Jupiters, size = 1.3 Jupiters. Thus, OGLE-TR-56b appears to be similar to HD 209458b, the only other known transiting giant planet. Unfortunately, our planet radius determination is uncertain due to the very limited precision of the ground-based photometry, and does not allow for a meaningful comparison with theoretical model predictions. We propose HST observations with the ACS-HRC of the main transit of OGLE-TR-56b, which will improve the precision and the accuracy of the planet parameters by close to a factor of 10. In addition, we propose a timing experiment for the planet's extremely close orbit {1.2-day period, 0.023 AU from the star}, which will allow us to detect the orbital decay and test convection theories. ACS 9984 Cosmic Shear With ACS Pure Parallels Small distortions in the shapes of background galaxies by foreground mass provide a powerful method of directly measuring the amount and distribution of dark matter. Several groups have recently detected this weak lensing by large-scale structure, also called cosmic shear. The high resolution and sensitivity of HST/ACS provide a unique opportunity to measure cosmic shear accurately on small scales. Using 260 parallel orbits in Sloan textiti {F775W} we will measure for the first time: beginlistosetlength sep0cm setlengthemsep0cm setlength opsep0cm em the cosmic shear variance on scales 0.7 arcmin, em the skewness of the shear distribution, and em the magnification effect. endlist Our measurements will determine the amplitude of the mass power spectrum sigma_8Omega_m^0.5, with signal-to-noise {s/n} ~ 20, and the mass density Omega_m with s/n=4. They will be done at small angular scales where non-linear effects dominate the power spectrum, providing a test of the gravitational instability paradigm for structure formation. Measurements on these scales are not possible from the ground, because of the systematic effects induced by PSF smearing from seeing. Having many independent lines of sight reduces the uncertainty due to cosmic variance, making parallel observations ideal. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTAR 9067: GS Acquisition (3,2,3) @ 182/09:45:05Z resulted in FL backup on FGS 3. HST was in LOS at time of event, upon AOS, there were no FGS flags indicating SRLEX or SSLEX. Under investigation. HSTAR 9069: GS Acquisition (1,3,3) @ 182/23:42:54Z resulted in FL backup on FGS 1 due to SSLE on FGS 3. U2,3FM @ 183/23:36:49Z and 182/23:39:34Z showed attitude errors. May @ 182/23:50:35Z showed errors. Under investigation. COMPLETED OPS REQs: 16998-0 Engineering Dump for BCT Critical Engineering Data @ 183/03:16:56z OPS NOTES EXECUTED: 1115-0 CCC IP CONFIG Connections @ 182/11:20z 1126-0 Bat Cap Test- Adjust CCC5 K1 Level2 Limits 183/0356z SCHEDULED SUCCESSFUL FAILURE TIMES FGS GSacq 13 13 FGS REacq 06 06 FHST Update 14 14 LOSS of LOCK SIGNIFICANT EVENTS: Initial commanding for Battery 4 Capacity Test started @ 182/10:27Z with configuration of TMDIAGs (OR 16996-1 with attached Battery 4 Capacity Test script). Battery 4 was connected to the Diode Bus C and high rate discharge was initiated @ 182/10:43Z, discharge continued nominally until approximately 182/23:57Z (during ZOE) when the 15 Volt termination point was reached. SA Section 4 was connected to Battery 4 @ 183/01:32Z for recharging the battery. Preliminary capacity is 55.8 Ah measured through the 5.1 Ohm resistor. Plan to configure the FSW back to a 6-battery system @ approximately 184/17:18Z. ---- Jacques :-) Editor: www.spacepatches.info ------------------------------------------------------ |
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