Status Report

NASA Hubble Space Telescope Daily Report #5118

By SpaceRef Editor
June 16, 2010
Filed under , ,


Continuing to Collect World Class Science

PERIOD COVERED: 5am June 15 – 5am June 16, 2010 (DOY 166/09:00z-167/09:00z)


Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)

HSTARS: (None)



FGS GSAcq 6 6
FGS REAcq 9 9
OBAD with Maneuver 4 4



COS/NUV 11538

COS-GTO: Imaging of Mid-UV Emissions from Io in Eclipse

The atmosphere and corona of Jupiter’s volcanic moon Io emit light at a wide variety of wavelengths, from FUV neutral O and S lines to SO emission at 1.7 microns. These emissions provide important constraints on the distribution and chemistry of Io’s atmosphere, and Io’s interaction with the Jovian magnetosphere. The neutral O and S FUV emissions, shortward of 2000, have been imaged extensively by HST/STIS and visible emissions (from neutral Na, K and O line emission, and SO2 continuum emission) have been imaged by the Galileo, Cassini, and New Horizons spacecraft, but the spatial distribution of emissions in the 2000-3000 region, thought to be dominated by SO2 electron impact continuum emission, has not yet been determined. Earlier long-slit observations with STIS indicated strong concentration of 2800? emission over the active volcano Prometheus (Jessup et al. 2004), suggesting local volcanic control, but Cassini images suggest that the SO2 continuum seen at longer wavelengths is instead concentrated over the sub-Jovian and anti-Jovian points where there are magnetic connections between Io and the Jovian magnetosphere- the anti-Jovian point is close to Prometheus. A series of 200-second integrations taken in Jupiter eclipse should determine whether emission is concentrated over volcanos or over the sub-Jovian point, and should be able to observe motion of the emission due to changing magnetic field orientation if it is magnetically controlled. This observation will also provide experience in the use of COS in imaging mode.


How Galaxies Acquire their Gas: A Map of Multiphase Accretion and Feedback in Gaseous Galaxy Halos

We propose to address two of the biggest open questions in galaxy formation – how galaxies acquire their gas and how they return it to the IGM – with a concentrated COS survey of diffuse multiphase gas in the halos of SDSS galaxies at z = 0.15 – 0.35. Our chief science goal is to establish a basic set of observational facts about the physical state, metallicity, and kinematics of halo gas, including the sky covering fraction of hot and cold material, the metallicity of infall and outflow, and correlations with galaxy stellar mass, type, and color – all as a function of impact parameter from 10 – 150 kpc. Theory suggests that the bimodality of galaxy colors, the shape of the luminosity function, and the mass-metallicity relation are all influenced at a fundamental level by accretion and feedback, yet these gas processes are poorly understood and cannot be predicted robustly from first principles. We lack even a basic observational assessment of the multiphase gaseous content of galaxy halos on 100 kpc scales, and we do not know how these processes vary with galaxy properties. This ignorance is presently one of the key impediments to understanding galaxy formation in general. We propose to use the high-resolution gratings G130M and G160M on the Cosmic Origins Spectrograph to obtain sensitive column density measurements of a comprehensive suite of multiphase ions in the spectra of 43 z < 1 QSOs lying behind 43 galaxies selected from the Sloan Digital Sky Survey. In aggregate, these sightlines will constitute a statistically sound map of the physical state and metallicity of gaseous halos, and subsets of the data with cuts on galaxy mass, color, and SFR will seek out predicted variations of gas properties with galaxy properties. Our interpretation of these data will be aided by state-of-the-art hydrodynamic simulations of accretion and feedback, in turn providing information to refine and test such models. We will also use Keck, MMT, and Magellan (as needed) to obtain optical spectra of the QSOs to measure cold gas with Mg II, and optical spectra of the galaxies to measure SFRs and to look for outflows. In addition to our other science goals, these observations will help place the Milky Way's population of multiphase, accreting High Velocity Clouds (HVCs) into a global context by identifying analogous structures around other galaxies. Our program is designed to make optimal use of the unique capabilities of COS to address our science goals and also generate a rich dataset of other absorption-line systems STIS/CC 11845 CCD Dark Monitor Part 2 Monitor the darks for the STIS CCD. STIS/CC 11847 CCD Bias Monitor-Part 2 Monitor the bias in the 1×1, 1×2, 2×1, and 2×2 bin settings at gain=1, and 1×1 at gain = 4, to build up high-S/N superbiases and track the evolution of hot columns. STIS/CCD 11849 STIS CCD Hot Pixel Annealing This purpose of this activity is to repair radiation induced hot pixel damage to the STIS CCD by warming the CCD to the ambient instrument temperature and annealing radiation-damaged pixels. Radiation damage creates hot pixels in the STIS CCD Detector. Many of these hot pixels can be repaired by warming the CCD from its normal operating temperature near -83 deg. C to the ambient instrument temperature (~ +5 deg. C) for several hours. The number of hot pixels repaired is a function of annealing temperature. The effectiveness of the CCD hot pixel annealing process is assessed by measuring the dark current behavior before and after annealing and by searching for any window contamination effects. STIS/CCD/MA2 11568 A SNAPSHOT Survey of the Local Interstellar Medium: New NUV Observations of Stars with Archived FUV Observations We propose to obtain high-resolution STIS E230H SNAP observations of MgII and FeII interstellar absorption lines toward stars within 100 parsecs that already have moderate or high-resolution far-UV (FUV), 900-1700 A, observations available in the MAST Archive. Fundamental properties, such as temperature, turbulence, ionization, abundances, and depletions of gas in the local interstellar medium (LISM) can be measured by coupling such observations. Due to the wide spectral range of STIS, observations to study nearby stars also contain important data about the LISM embedded within their spectra. However, unlocking this information from the intrinsically broad and often saturated FUV absorption lines of low-mass ions, (DI, CII, NI, OI), requires first understanding the kinematic structure of the gas along the line of sight. This can be achieved with high resolution spectra of high-mass ions, (FeII, MgII), which have narrow absorption lines, and can resolve each individual velocity component (interstellar cloud). By obtaining short (~10 minute) E230H observations of FeII and MgII, for stars that already have moderate or high- resolution FUV spectra, we can increase the sample of LISM measurements, and thereby expand our knowledge of the physical properties of the gas in our galactic neighborhood. STIS is the only instrument capable of obtaining the required high resolution data now or in the foreseeable future. WFC3/ACS/IR 11731 Studying Cepheid Systematics in M81: H-Band Observations The local value of the Hubble Constant remains one of the most important constraints in cosmology, but improving on the 10% accuracy of the HST Key Project is challenging. No improvements will be convincing until the metallicity dependence is well constrained and blending effects are fully understood. M81 and its dwarf companion Holmberg IX are superb laboratories for studying Cepheid systematics because they contain large numbers of bright Cepheids with a good spread in metallicity lying at a common, relatively close distance. We have identified 180 12< P< 70 day Cepheids in these two galaxies using the Large Binocular Telescope (compared to 30 in total by the KP), and will expand the sample further in 2008-2009. We will use 10 orbits with WFC3/IR to obtain H-band images of 100 Cepheids in M81 to add to the ACS/BVI calibrations we will obtain from archival data and 1 orbit with WFC3/UVIS to add B-band data for Holmberg IX. Four band BVIH photometry will allow us to flux calibrate, estimate extinction, measure metallicity effects and then check the results in detail. We can also examine blending effects on WFC3/IR data in a relatively nearby galaxy before it is applied to more distant galaxies. Our M81 sample is three times larger than the next best sample, that of NGC4258, and suffers less from blending because M81 is at half the distance, so it is an excellent laboratory for studying Cepheid systematics even if it lacks as precise a geometric distance as NGC4258. WFC3/IR 11694 Mapping the Lnteraction Between High-Redshift Galaxies and the Lntergalactic Environment With the commissioning of the high-throughput large-area camera WFC3/IR, it is possible for the first time to undertake an efficient survey of the rest-frame optical morphologies of galaxies at the peak epoch of star formation in the universe. We therefore propose deep WFC3/IR imaging of over 320 spectroscopically confirmed galaxies between redshift 1.6 < z < 3.4 in well-studied fields which lie along the line of sight to bright background QSOs. The spectra of these bright QSOs probe the IGM in the vicinity of each of the foreground galaxies along the line of sight, providing detailed information on the physical state of the gas at large galactocentric radii. In combination with our densely sampled UV/IR spectroscopy, stellar population models, and kinematic data in these fields, WFC3/IR imaging data will permit us to construct a comprehensive picture of the structure, dynamics, and star formation properties of a large population of galaxies in the early universe and their effect upon their cosmological environment. WFC3/IR 11921 WFC3 IR PSF Wings The IR PSF wings will be evaluated at 5 field points (near the field center and corners) in two filters (F098M and F160W) to check for image stability. Full frame images of a moderately bright, isolated star will be obtained at each field position with a series of increasing exposure times designed to permit construction of a very high SNR PSF with dynamic range sufficient to evaluate the wing intensity to >5 arcsec radius. The images will also permit examination of potential straylight effects, electronic cross-talk and image persistence.

This is a repeat of SMOV activity WFC3-26 (program 11439.) The results of the two programs will be compared. The data will be analyzed using the code and techniques described in ISR WFC3 2008-41 (Hartig). Profiles of encircled energy will be compared to those obtained from program 11439.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more reliably removed from science data using darks taken with the same exposure sequences as the science data, than with a single dark current image scaled by desired exposure time. Therefore, dark current images must be collected using all sample sequences that will be used in science observations. These observations will be used to monitor changes in the dark current of the WFC3-IR channel on a day-to-day basis, and to build calibration dark current ramps for each of the sample sequences to be used by Gos in Cycle 17. For each sample sequence/array size combination, a median ramp will be created and delivered to the calibration database system (CDBS).

WFC3/UV 11906


The absolute gain of each quadrant of the WFC3 UVIS detector will be measured for the nominal detector readout configuration and at the on-orbit operating temperature.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K subarray biases are acquired at less frequent intervals throughout the cycle to support subarray science observations. The internals from this proposal, along with those from the anneal procedure (Proposal 11909), will be used to generate the necessary superbias and superdark reference files for the calibration pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the UVIS detector (both CCDs) at the level of ~1%, lasting hours to days. Initially found via an unexpected bowtie-shaped feature in flatfield ratios, subsequent lab tests on similar e2v devices have since shown that it is also present as simply an overall offset across the entire CCD, i.e., a QE offset without any discernable pattern. These lab tests have further revealed that overexposing the detector to count levels several times full well fills the traps and effectively neutralizes the bowtie. Each visit in this proposal acquires a set of three 3×3 binned internal flatfields: the first unsaturated image will be used to detect any bowtie, the second, highly exposed image will neutralize the bowtie if it is present, and the final image will allow for verification that the bowtie is gone.

WFC3/UVIS/IR 11700

Bright Galaxies at z>7.5 with a WFC3 Pure Parallel Survey

The epoch of reionization represents a special moment in the history of the Universe as it is during this era that the first galaxies and star clusters are formed. Reionization also profoundly affects the environment where subsequent generations of galaxies evolve. Our overarching goal is to test the hypothesis that galaxies are responsible for reionizing neutral hydrogen. To do so we propose to carry out a pure parallel WFC3 survey to constrain the bright end of the redshift z>7.5 galaxy luminosity function on a total area of 176 arcmin^2 of sky. Extrapolating the evolution of the luminosity function from z~6, we expect to detect about 20 Lyman Break Galaxies brighter than M_* at z~8 significantly improving the current sample of only a few galaxies known at these redshifts. Finding significantly fewer objects than predicted on the basis of extrapolation from z=6 would set strong limits to the brightness of M_*, highlighting a fast evolution of the luminosity function with the possible implication that galaxies alone cannot reionize the Universe. Our observations will find the best candidates for spectroscopic confirmation, that is bright z>7.5 objects, which would be missed by small area deeper surveys. The random pointing nature of the program is ideal to beat cosmic variance, especially severe for luminous massive galaxies, which are strongly clustered. In fact our survey geometry of 38 independent fields will constrain the luminosity function like a contiguous single field survey with two times more area at the same depth. Lyman Break Galaxies at z>7.5 down to m_AB=26.85 (5 sigma) in F125W will be selected as F098M dropouts, using three to five orbits visits that include a total of four filters (F606W, F098M, F125W, F160W) optimized to remove low-redshift interlopers and cool stars. Our data will be highly complementary to a deep field search for high- z galaxies aimed at probing the faint end of the luminosity function, allowing us to disentangle the degeneracy between faint end slope and M_* in a Schechter function fit of the luminosity function. We waive proprietary rights for the data. In addition, we commit to release the coordinates and properties of our z>7.5 candidates within one month from the acquisition of each field.

SpaceRef staff editor.