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Daily Report #3745 DOY 334
HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science
DAILY REPORT # 3745 PERIOD COVERED: DOY 334 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 10238 The nature of quasar host galaxies: combining ACS imaging and VLT Integral Field Spectroscopy. We propose to perform ACS/F606W imaging of a complete sample of 29 quasar host galaxies {0.08z0.34}. The spatial resolving power of the ACS HRC, in combination with the acquisition of empirical PSFs and advanced deconvolution techniques, will allow to study in detail structures on scales of a few tens of parsecs, and to access the inner regions of the host galaxies, even in the presence of bright nuclei. We demonstrate that combining deep spectroscopy with high resolution imaging in stable PSF conditions definitely constitutes the solution to characterize the complex physical properties of quasar host galaxies, from their outer regions to the inner 0.1 kpc, where most of the information on the interplay between quasars and their hosts is hidden. We propose to combine new ACS images with existing Integral Field VLT Spectra. We will map the stellar and gas velocity fields in 2D, constrain the mass models, derive the radial host M/L ratios, map and characterize the stellar populations and the ionization state of the gas. 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/HRC/WFC 10409 Highly episodic mass loss on the AGB: imaging in scattered stellar light We have discovered that some nearby bright carbon stars have detached circumstellar shells, emitting in CO mm lines as well as in visual stellar light scattered by dust and atoms {the resonance lines of NaI and KI}. The optical light is up to 35% linearly polarized. The shells are remarkably spherical, but both the CO data and the optical pictures show pronounced inhomogeneities on smaller {marginally resolved} scales. The latter fact introduces considerable uncertainties in mass-loss-rate estimates. We ascribe the existence of the shells to the He-shell flashes, and the inhomogeneities to hydrodynamic instabilities. However, the different observables {CO, atoms, dust} indicate significantly different structural patterns. In order to understand the different components of the shells, their interaction and origin, it is necessary to improve the imaging of the shells. In view of their faintness, relative to the stellar light scattered in the Earth's atmosphere, this can only be accomplished by using the HST. Maps of the distribution of the dust at high spatial resolution will efficiently constrain theoretical work on the origin of the shells and their evolution, and the inhomogeneities in them. We may be able to separate the dust and atomic scattered light components. Mass loss from carbon stars and other AGB stars contribute significantly to the abundances of many chemical elements {C, N, s-elements} and is not well understood. The present study may lead to important improvements in the study of mass-loss rates and mechanisms, and thus for nucleosynthesis in general. ACS/WFC 10181 ACS/NICMOS Imaging of Bright Lyman Break Galaxy Candidates from SDSS The recent surprising discovery of six unusually bright {r~20 mag} Lyman break galaxy {LBG} candidates with z=2.45-2.80 in the Sloan Digital Sky Survey {SDSS} raises a number of questions that only HST can address. Specifically, what is the true nature of these objects, and what role if any is played by gravitational lensing? We propose to use the superior resolution and sensitivity of ACS and NICMOS to obtain deep images of these objects and their environments. Compared to SDSS images, HST will allow us to determine their morphologies {extended, point-source, or lensed}, the appearance of their environments {rich or poor}, and to detect any faint foreground groups or clusters that might be responsible for lensing these objects. All outcomes would be intriguing. If the objects are lensed, it increases from 1 {MS1512-cB58} to 7 the number of normal LBGs bright enough to study individually. If they are instead unlensed point sources, they will represent a new class of previously unidentified absorption-line quasars. Finally, if they are unlensed and extended star-forming galaxies, they are at least 4mag brighter than L_* LBGs, thus making them the most luminous star-forming objects yet seen, representing a heretofore unknown extreme population of objects. ACS/WFC/WFPC2 10092 The COSMOS 2-Degree ACS Survey We will undertake a 2 square degree imaging survey {Cosmic Evolution Survey -- COSMOS} with ACS in the I {F814W} band of the VIMOS equatorial field. This wide field survey is essential to understand the interplay between Large Scale Structure {LSS} evolution and the formation of galaxies, dark matter and AGNs and is the one region of parameter space completely unexplored at present by HST. The equatorial field was selected for its accessibility to all ground-based telescopes and low IR background and because it will eventually contain ~100, 000 galaxy spectra from the VLT-VIMOS instrument. The imaging will detect over 2 million objects with I 27 mag {AB, 10 sigma}, over 35, 000 Lyman Break Galaxies {LBGs} and extremely red galaxies out to z ~ 5. COSMOS is the only HST project specifically designed to probe the formation and evolution of structures ranging from galaxies up to Coma-size clusters in the epoch of peak galaxy, AGN, star and cluster formation {z ~0.5 to 3}. The size of the largest structures necessitate the 2 degree field. Our team is committed to the assembly of several public ancillary datasets including the optical spectra, deep XMM and VLA imaging, ground-based optical/IR imaging, UV imaging from GALEX and IR data from SIRTF. Combining the full-spectrum multiwavelength imaging and spectroscopic coverage with ACS sub-kpc resolution, COSMOS will be Hubble's ultimate legacy for understanding the evolution of both the visible and dark universe. 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 8794 NICMOS Post-SAA calibration - CR Persistence Part 5 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 10337 The COSMOS 2-Degree ACS Survey NICMOS Parallels The COSMOS 2-Degree ACS Survey NICMOS Parallels. This program is a companion to program 10092. 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. WFPC2 10359 WFPC2 CYCLE 13 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 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.) HSTARs: HSTAR 9614: GS Acquistion (2,1,1) @ 335/01:43:54Z ended in FL backup on FGS 1 due to SSLE on FGS 2. Telemetry was acquired @ 335/01:50:32Z with GS acquisition already complete. COMPLETED OPS REQs: Successfully completed SPA Reconfiguration pre-TGS OOT, Day 2 @ 334/15:45Z. OPS NOTES EXECUTED: SCHEDULED SUCCESSFUL FAILURE TIMES FGS Gsacq 12 12 FGS Reacq 5 5 FHST Update 15 15 LOSS of LOCK SIGNIFICANT EVENTS: None |
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