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Daily 3655
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3655 PERIOD COVERED: DOY 197 OBSERVATIONS SCHEDULED ACS/HRC 10050 ACS Earth Flats High signal sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the flats currently used by the pipeline and will provide a comparison with flats derived via other techniques: L-flats from stellar observations, sky flats from stacked GO observations, and internal flats using the calibration lamps. Weekly coronagraphic monitoring is required to assess the changing position of the spots. ACS/HRC 10130 Systemic Proper Motions of the Magellanic Clouds from Astrometry with ACS: II. Second Epoch Images We request second epoch observations with ACS of Magellanic Cloud fields centered on the 40 quasars in the LMC and SMC for which we have first epoch Cycle 11 data. The new data will determine the systemic proper motion of the Clouds. An extensive astrometric analysis of the first epoch data shows that follow-up observations with a two year baseline will allow us to measure the proper motion of the clouds to within 0.022 mas/year in each of the two orthogonal directions {assuming that we can image 25 quasars, i.e., with a realistic Snapshot Program completion rate}. The best weighted combination of all previous measurements has a seven times larger error than what we expect. We will determine the proper motion of the clouds with 2% accuracy. When combined with HI data for the Magellanic Stream this will constrain both the mass distribution in the Galactic Halo and theoretical models for the origin of the Magellanic Stream. Previous measurements are too crude for such constraints. Our data will provide by far the most accurate proper motion measurement for any Milky Way satellite. ACS/HRC 10204 Evolution of Light Echoes of SN 1993J SN 1993J is the nearest SN in the last decade, and only one of seven objects to produce confirmed light echoes. Our analyses of archival HST/WFPC2 data revealed that the SN has illuminated at least two light-echo structures in the galaxy M81. Those echoes appear to define two sheets of dust, located roughly 260 ly and 770 ly in front of the SN, which are the first, and most efficient, 3-D probes of the ISM in M81. The echoes not only reveal the ISM's structure, but also constrain the density, composition and grain-size of its dust. Echoes are transient events, and as they change on timescales shorter than a year, continued monitoring will reveal new illuminated material, tracing interstellar and circumstellar structure. We propose a modest and highly efficient campaign by HST to image these and yet undiscovered echoes toward SN 1993J. Such observations will build the first direct 3-D map of the ISM within a million cubic parsecs of M81's spiral arm, and may glimpse the circumstellar environment affected by the projenitor's mass loss. Such results probe the nature of extragalactic dust, reveal spatio-kinematic information about the M81's disk, tightly constrain its internal extinction, and under the proper circumstances, provide an independent distance measurement to the host galaxy. 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 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/WFC 10046 CCD Hot Pixel Annealing Hot pixel annealing will be performed once every 4 weeks. The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C. This state will be held for approximately 12 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition. To assess the effectiveness of this procedure, a bias and two dark images will be taken after the annealing procedure for both WFC and HRC. The HRC darks are taken in parallel with the WFC darks. ACS/WFC 10248 Current star formation in young, compact clusters in the Small Magellanic Cloud The Small Magellanic Cloud {SMC} offers a deep, resolved stellar population that leverages fundamental parameters {metallicity, dust content} with respect to the Milky Way and to its most studied counterpart, the LMC. Its subsolar metallicity makes it the best analog to the large majority of dwarf irregulars, and gives us the possibility to study star formation and evolution in an environment with the closest {available} resemblance to the early universe. Young, compact clusters are ideal laboratories to investigate how these fundamental differences affect star and cluster formation and evolution. We are therefore, proposing, to use ACS and NICMOS to perform a in depth study of the "resolved" stellar population in the four youngest compact clusters in the SMC. The observations, spanning the UV to the near-IR, will reach the subsolar domain, and will address the following fundamental questions: Does the IMF follow the universal Salpeter's law? Is mass segregation prevalent in the SMC clusters as in LMC clusters? Is on-going star formation present, where and how? What is the role of massive star feedback? The four proposed clusters span an age range from 3-20 Myr, and sample spatially different regions of the SMC. The synergy with NICMOS will permit full characterization of existing pre main sequence stars, if detected. This proposal is part of a coordinated HST and ground-based study of the stellar history and star formation processes in the SMC. 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. NIC3 9846 The Origins of Sub-stellar Masses: Searching for the End of the IMF Is there a preferred scale that defines the end of the IMF? We propose to test this hypothesis by conducting a deep spectroscopic survey of extremely low mass objects in the embedded young cluster associated with NGC1333. At a distance of only 300pc, this cluster is one of the nearest examples of a dense young cluster. We will be able to obtain R=200 spectra and photometry for 40-60 cluster members with masses between 5-40 Jupiter masses at an age of 1 Myr observed through A{v}10 mag. This will enable us to estimate temperatures and luminosities for all sources detected in the survey. We will compare their positions in an H-R diagram to PMS evolutionary tracks in order to estimate their ages and masses. For a solar metallicity cloud at a temperature of 10 K, the minimum mass for fragmentation is thought to be 10 Jupiter masses. A statistically significant sample of objects detected below this limit would challenge the role of hierarchical fragmentation in limiting substellar masses. The proximity of this cluster combined with the unique sensitivity, wavelength coverage, and multi-object spectroscopic capability of NICMOS on HST make this experiment possible. 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 10175 STIS Snapshot Survey of Boron Abundances in Early-B Stars Boron abundances in massive stars provide a unique constraint for new theoretical models of stellar evolution that include rotation. We propose to use STIS to measure the B III doublet near 2066 Angstroms in a large sample of early-B stars. A high priority will be placed on obtaining abundances for several stars in each of a number of different young clusters, associations, and star forming regions. This will allow quantitative comparison with theoretical predictions of rotationally driven mixing in early B stars as function of mass, age, and rotation rate. Since boron abundance measurements are not possible for large vsin{i} values, and sin{i} is not known for individual stars, a large sample is required to statistically test the predictions of boron depletion as a function of the true rotation rate. For bright nearby stars {25 targets} we will use the G230MB grating and obtain very high S/N {200:1}. This avoids the need for an ND filter which would discard 99% of the photons. Spectral synthesis techniques will allow us to derive accurate abundances despite the moderate resolution of this grating, even for stars with relatively high vsin{i} values. This is especially important in testing rotational models, as current abundance measurements are mostly for stars with much lower than average rotation rates. For fainter, more distant stars {27 targets} we will use the E230M or E230H grating with the 0.2x0.2 aperture. STIS/CCD 9885 Probing the High Redshift Universe with Quasar Emission Lines The quasar epoch is believed to be associated with the birth of the most massive galaxies, a time marked by rapid star formation and evolution. Quasar emission lines can reveal the chemical evolution and physical state of gas in the very center of these galaxies. Analysis of the observed line strengths, using tools that have recently become available, implies that the chemical composition of the emitting gas correlates with quasar luminosity in a way that is suggestive of the known galactic mass/luminosity/metallicity correlations. The emission lines can also reveal the form of the ionizing radiation field emitted by the central object. Understanding the evolution of the central powerhouse is important for black hole accretion physics and because its spectrum is likely to dominate the ionization of the IGM. There are many high-ionization permitted emission lines in the region below 1000A rest wavelength that can provide important new constraints on these measurements. Thus, there is a critical need for spectra over the full rest-wavelength range ~ 600A through the UV. Through a pilot Cycle 10 archival study, we have identified the QSO HE 1122-1648 as an optimal object for such a study. This QSO has a sufficiently high redshift {z = 2.4} so that we can see down to very short rest wavelengths {463A} in observed-wavelength regions where STIS has high sensitivity, and lies on a line of sight with an unusually low density of intervening Ly-alpha absorber clouds. A high-quality spectrum of this object will have implications for the ionization of the IGM and will leverage the unique UV capabilities of HST to complement the galaxy formation studies that NGST will do at higher redshift. WFPC2 10067 WFPC2 Cycle 12 Decontaminations and Associated Observations This proposal is for the monthly WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check. 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. 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 07 07 FGS REacq 05 05 FHST Update 12 12 LOSS of LOCK SIGNIFICANT EVENTS: None |
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