NASA Hubble Space Telescope Daily Report #5052
HUBBLE SPACE TELESCOPE DAILY REPORT #5052
Continuing to Collect World Class Science
PERIOD COVERED: 5am March 12 – 5am March 15, 2010 (DOY 071/10:00z-073/10:00z)
OBSERVATIONS SCHEDULED
WFC3/UV 12077
Monitoring the Aftermath of an Asteroid Impact Event
Our Director’s Discretionary program (GO-12053) to image the newly discovered object P/2010 A2 executed successfully on 2010 Jan 25 and 29 with spectacular results. Hubble has apparently borne witness to the first detection of a collision in the asteroid belt. Hubble imaging with the WFC3 has revealed an object unlike anything ever seen before and with details impossible to detect with any other facility. We request 6 more orbits of Hubble time (1 orbit every 20 days over the next few months, until the object enters Hubble’s solar exclusion zone in late-June 2010) to monitor the evolution of this remarkable object and further clarify the nature of this event. These observations may usher in a new era of searching for and characterizing collisional events within the asteroid belt.
ACS/WFC/WFC3/UV 12020
The Deepest Stellar X-ray/optical Census of the Bulge
We have obtained the deepest optical dataset ever taken or planned towards the bulge, allowing bulge/disk decomposition down to F606W=23 and variability monitoring over seven days, diagnostics not available for any bulge field observed by Chandra. We propose ACIS-I imaging to identify X-ray point sources in this field. This will directly trace a number of fundamental yet poorly-constrained parameters of the inner Milky Way, for example the spin-down timescale of stars along the disk and bulge; the formation history of the bulge and, for the first time, direct constraints on the gravitational potential of the inner milky way through AGN-enabled absolute proper motions. Our proposed survey will be an essential calibrator for other X-ray/optical surveys of the bulge both past and planned.
ACS/WFC 11995
CCD Daily Monitor (Part 2)
This program comprises basic tests for measuring the read noise and dark current of the ACS WFC and for tracking the growth of hot pixels. The recorded frames are used to create bias and dark reference images for science data reduction and calibration. This program will be executed four days per week (Mon, Wed, Fri, Sun) for the duration of Cycle 17. To facilitate scheduling, this program is split into three proposals. This proposal covers 320 orbits (20 weeks) from 1 February 2010 to 20 June 2010.
WFC3/IR 11931
IR Signal Non-Linearity Calibration
These observations will be used to quantify the non-linear signal behavior of the IR channel, as well as to create the IR channel non-linearity calibration reference file. The non-linearity behavior of each pixel in the detector will be investigated through the use of flat fields, while the photometric behavior of point sources will be studied using observations of 47 Tuc.
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/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 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).
STIS/MA1/MA2 11857
STIS Cycle 17 MAMA Dark Monitor
This proposal monitors the behavior of the dark current in each of the MAMA detectors.
The basic monitor takes two 1380s ACCUM darks each week with each detector. However, starting Oct 5, pairs are only included for weeks that the LRP has external MAMA observations planned. The weekly pairs of exposures for each detector are linked so that they are taken at opposite ends of the same SAA free interval. This pairing of exposures will make it easier to separate long and short term temporal variability from temperature dependent changes.
For both detectors, additional blocks of exposures are taken once every six months. These are groups of five 1314s FUV-MAMA Time-Tag darks or five 3x315s NUV ACCUM darks distributed over a single SAA-free interval. This will give more information on the brightness of the FUV MAMA dark current as a function of the amount of time that the HV has been on, and for the NUV MAMA will give a better measure of the short term temperature dependence.
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/CC 11845
CCD Dark Monitor Part 2
Monitor the darks for the STIS CCD.
WFC3/IR 11838
Completing a Flux-limited Survey for X-ray Emission from Radio Jets
We will measure the changing flow speeds, magnetic fields, and energy fluxes in well-resolved quasar jets found in our short-exposure Chandra survey by combining new, deep Chandra data with radio and optical imaging. We will image each jet with sufficient sensitivity to estimate beaming factors and magnetic fields in several distinct regions, and so map the variations in these parameters down the jets. HST observations will help diagnose the role of synchrotron emission in the overall SED, and may reveal condensations on scales less than 0.1 arcsec.
COS/FUV/NUV 11828
X-ray and FUV Photo-Ionization/-Excitation of Transitional Disks Around thePMS Stars HD135344B and Lk Halpha 330
Transitional disks have transformed most of the dust and gas in their inner regions into planetesimals or larger solid bodies. They are a rare, short-lived phase of PMS disk evolution and provide important physical insights and modeling constraints on disk and protoplanetary system evolution. We propose to observe two intermediate mass stars with transitional disks, HD135344B and Lk Halpha 330, using ACIS-S on Chandra and the COS FUV spectrograph on HST. We will use these spectra to determine the coronal, transition region, and upper chromospheric emission measure distribution, covering temperatures from 10, 000 K to 10 MK, and then calculate the full X-ray/EUV/FUV radiation field for use in modeling its photoexcitation/photoionization effects on the disk structure.
STIS/CCD/MA1 11737
The Distance Dependence of the Interstellar N/O Abundance Ratio: A Gould Belt Influence?
The degree of elemental abundance homogeneity in the interstellar medium is a function of the enrichment and mixing processes that govern galactic chemical evolution. Observations of young stars and the interstellar gas within ~500 pc of the Sun have revealed a local ISM that is so well-mixed it is having an impact on ideas regarding the formation of extrasolar planets. However, the situation just beyond the local ISM is not so clear. Sensitive UV absorption line measurements have recently revealed a pattern of inhomogeneities in the interstellar O, N, and Kr gas-phase abundances at distances of ~500 pc and beyond that appear nucleosynthetic in origin rather than due to dust depletion. In particular, based on a sample of 13 sightlines, Knauth et al. (2006) have found that the nearby stars (d < 500 pc) exhibit a mean interstellar N/O abundance ratio that is significantly higher (0.18 dex) than that toward the more distant stars. Interestingly, all of their sightlines lie in the sky vicinity of the Gould Belt of OB associations, molecular clouds, and diffuse gas encircling the Sun at a distance of ~400 pc. Is it possible that mixing processes have not yet smoothed out the recent ISM enrichment by massive stars in the young Belt region? By measuring the interstellar N/O ratios in a strategic new sample of sightlines with STIS, we propose to test the apparent N/O homogeneity inside the Gould Belt and determine if the apparent decline in the N/O ratio with distance is robust and associated with the Belt region. WFC3/UV/IR 11664 The WFC3 Galactic Bulge Treasury Program: Populations, Formation History, and Planets Exploiting the full power of the Wide Field Camera 3 (WFC3), we propose deep panchromatic imaging of four fields in the Galactic bulge. These data will enable a sensitive dissection of its stellar populations, using a new set of reddening-free photometric indices we have constructed from broad-band filters across UV, optical, and near-IR wavelengths. These indices will provide accurate temperatures and metallicities for hundreds of thousands of individual bulge stars. Proper motions of these stars derived from multi-epoch observations will allow separation of pure bulge samples from foreground disk contamination. Our catalogs of proper motions and panchromatic photometry will support a wide range of bulge studies. Using these photometric and astrometric tools, we will reconstruct the detailed star-formation history as a function of position within the bulge, and thus differentiate between rapid- and extended-formation scenarios. We will also measure the dependence of the stellar mass function on metallicity, revealing how the characteristic mass of star formation varies with chemistry. Our sample of bulge stars with accurate metallicities will include 12 candidate hosts of extrasolar planets. Planet frequency is correlated with metallicity in the solar neighborhood; our measurements will extend this knowledge to a remote environment with a very distinct chemistry. Our proposal also includes observations of six well-studied globular and open star clusters; these observations will serve to calibrate our photometric indices, provide empirical population templates, and transform the theoretical isochrone libraries into the WFC3 filter system. Besides enabling our own program, these products will provide powerful new tools for a host of other stellar-population investigations with HST/WFC3. We will deliver all of the products from this Treasury Program to the community in a timely fashion. COS/NUV/FUV 11659 Probing the Interior of SN1006 The remnant of SN 1006 is unique among all supernova remnants in having 3 identified background UV sources that can be used to probe cold, otherwise unseen ejecta within the remnant shell. We propose high-resolution spectra from COS to obtain spectra of all three of these. The brightest of these, the Schweizer-Middleditch star (the only one with extensive previous high-quality UV spectra) shows Si II absorption with an extremely unusual asymmetric profile with a sharp edge on the red end, indicating the velocity of material just entering the reverse shock. Our new spectrum can be compared with STIS observations from 1999 to measure definitively the velocity change as the reverse shock eats its way into ever-more- slowly-expanding ejecta. One may well ask, however, if this profile is truly representative, and we seek to answer that with a spectrum of a background quasar at a similar distance of the SM star from the projected center, but in a different direction. And by investigating the detailed structure of these two sources and a second quasar, we can probe small-scale structure in the ejecta. No object other than SN1006 offers a similar opportunity to probe the distribution of ejecta within the remnant of a Type Ia supernova. WFC3/UVIS 11657 The Population of Compact Planetary Nebulae in the Galactic Disk We propose to secure narrow- and broad-band images of compact planetary nebulae (PNe) in the Galactic Disk to study the missing link of the early phases of post-AGB evolution. Ejected AGB envelopes become PNe when the gas is ionized. PNe expand, and, when large enough, can be studied in detail from the ground. In the interim, only the HST capabilities can resolve their size, morphology, and central stars. Our proposed observations will be the basis for a systematic study of the onset of morphology. Dust properties of the proposed targets will be available through approved Spitzer/IRS spectra, and so will the abundances of the alpha- elements. We will be able thus to explore the interconnection of morphology, dust grains, stellar evolution, and populations. The target selection is suitable to explore the nebular and stellar properties across the galactic disk, and to set constraints on the galactic evolutionary models through the analysis of metallicity and population gradients. WFC3/UVIS/IR 11644 A Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into the Formation of the Outer Solar System The eight planets overwhelmingly dominate the solar system by mass, but their small numbers, coupled with their stochastic pasts, make it impossible to construct a unique formation history from the dynamical or compositional characteristics of them alone. In contrast, the huge numbers of small bodies scattered throughout and even beyond the planets, while insignificant by mass, provide an almost unlimited number of probes of the statistical conditions, history, and interactions in the solar system. To date, attempts to understand the formation and evolution of the Kuiper Belt have largely been dynamical simulations where a hypothesized starting condition is evolved under the gravitational influence of the early giant planets and an attempt is made to reproduce the current observed populations. With little compositional information known for the real Kuiper Belt, the test particles in the simulation are free to have any formation location and history as long as they end at the correct point. Allowing compositional information to guide and constrain the formation, thermal, and collisional histories of these objects would add an entire new dimension to our understanding of the evolution of the outer solar system. While ground based compositional studies have hit their flux limits already with only a few objects sampled, we propose to exploit the new capabilities of WFC3 to perform the first ever large-scale dynamical-compositional study of Kuiper Belt Objects (KBOs) and their progeny to study the chemical, dynamical, and collisional history of the region of the giant planets. The sensitivity of the WFC3 observations will allow us to go up to two magnitudes deeper than our ground based studies, allowing us the capability of optimally selecting a target list for a large survey rather than simply taking the few objects that can be measured, as we have had to do to date. We have carefully constructed a sample of 120 objects which provides both overall breadth, for a general understanding of these objects, plus a large enough number of objects in the individual dynamical subclass to allow detailed comparison between and within these groups. These objects will likely define the core Kuiper Belt compositional sample for years to come. While we have many specific results anticipated to come from this survey, as with any project where the field is rich, our current knowledge level is low, and a new instrument suddenly appears which can exploit vastly larger segments of the population, the potential for discovery — both anticipated and not — is extraordinary. WFC3/ACS/UVIS 11603 A Comprehensive Study of Dust Formation in Type II Supernovae with HST, Spitzer, and Gemini The recent discovery of three extremely bright Type II SNe, (2007it, 2007oc, 2007od) gives us a unique opportunity to combine observations with HST, Spitzer, and Gemini to study the little understood dust formation process in Type II Sne. Priority 1 Spitzer Cycle 5 and band 1 Gemini 2008A time has already been approved for this project. Since late-time Type II Sne are faint and tend to be in crowded fields, we need the high sensitivity and high spatial resolution of ACS and NICMOS/NIC2 for these observations. This project is motivated by the recent detection of large amounts of dust in high redshift galaxies. The dust in these high-z galaxies must come from young, massive stars so Type II Sne could be potential sources. The mechanism and the efficiency of dust condensation in Type II SN ejecta are not well understood, largely due to the lack of observational data. We plan to produce a unique dataset, combining spectroscopy and imaging in the visible, near- and mid-IR covering the key phase, 400-700 days after maximum when dust is known to form in the SN ejecta. Therefore, we are proposing for coordinated HST/NOAO observations (HST ACS, NICMOS/NIC2 & Gemini/GMOS and TReCS) which will be combined with our Spitzer Cycle 5 data to study these new bright Sne. The results of this program will place strong constraints on the formation of dust seen in young high redshift (z>5) galaxies.
WFC3/UV 11602
High-resolution imaging of three new UV-bright lensed arcs
We have identified and spectroscopically confirmed three new strongly lensed, UV-bright star-forming galaxies at z ~ 2 that are similar to the well-studied gravitationally lensed Lyman Break Galaxy (LBG) MS1512-cB58, and are of comparable brightness to the ”8 O’Clock Arc” (Allam et al. 2007) and ”Clone” systems (Lin et al. 2008). The 8 O’Clock Arc and Clone have already been awarded 20 orbits for deep WFPC2 and NICMOS imaging in five bands (HST cycle 16, Program 11167, PI: Allam). Adding these three recently discovered objects thus completes a unique set of the brightest known strongly lensed galaxies at z ~ 2, with magnitudes of r~20-21, and they provide a new window into the detailed study of the properties of high redshift galaxies. We propose 21 orbits for deep WFC3 imaging in five bands (F475W, F606W, F814W, F110W, and F160W) in order to construct detailed lensing models, to probe the mass and light profiles of the lensing galaxies and their environments, and to constrain the spectral energy distributions, star formation histories, and morphologies of the lensed galaxies.
WFC3/IR 11587
Probing Population III Star Formation in a z=7 Galaxy
Population III (Pop III) stars, the first generation, metal-free stars in the Universe, have been a main focus of the studies of early galaxy formation and reionization. HeII 1640 emission originates from energetic ionizing photons beyond 54.4eV, and is an ideal tracer of massive Pop III star formation with strong far-UV radiation. HeII has not yet been detected directly in individual galaxies at z<6.3, indicating a small contribution of Pop III star formation at those redshifts. We propose to use WFC3 narrow-band imaging to measure the flux of HeII emission in galaxy IOK-1 (z=6.96), the highest redshift spectroscopically confirmed galaxy to date. At this redshift, the HeII line is perfectly located in the WFC3 F130N filter passband. Our deep narrow-band imaging will detect a HeII flux down to 4x10^-18 erg/s/cm^2 at the 5-sigma level, corresponding to a star formation rate from massive Pop III stars of ~1 M_sun per year, a factor of ~5 improvement to the best ground-based results at lower redshift. Strong HeII emission, if detected, will provide the first direct evidence of significant Pop III formation in early galaxies at the end of the reionization epoch. We will also carry out short F125W broad-band observations to measure the rest-frame UV flux of this galaxy in order to constrain its total star formation rate and to provide continuum subtraction for narrow-band imaging.
WFC3/ACS/UVIS/IR 11570
Narrowing in on the Hubble Constant and Dark Energy
A measurement of the Hubble constant to a precision of a few percent would be a powerful aid to the investigation of the nature of dark energy and a potent “end-to end” test of the present cosmological model. In Cycle 15 we constructed a new streamlined distance ladder utilizing high- quality type Ia supernova data and observations of Cepheids with HST in the near-IR to minimize the dominant sources of systematic uncertainty in past measurements of the Hubble constant and reduce its total uncertainty to a little under 5%. Here we propose to exploit this new route to reduce the remaining uncertainty by more than 30%, translating into an equal reduction in the uncertainty of the equation of state of dark energy. We propose three sets of observations to reach this goal: a mosaic of NGC 4258 with WFC3 in F160W to triple its sample of long period Cepheids, WFC3/F160W observations of the 6 ideal SN Ia hosts to triple their samples of Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN 2007af, to discover and measure its Cepheids and begin expanding the small set of SN Ia luminosity calibrations. These observations would provide the bulk of a coordinated program aimed at making the measurement of the Hubble constant one of the leading constraints on dark energy.
ACS/WFC 11558
Planetary Nebulae, Globular Clusters and Binary Mergers
Four planetary nebulae (PNe) have been found within 130 of the 150 globular clusters (GCs) of our Galaxy. This might not seem like many, but stellar evolution predicts that the old populations of these clusters should contain no PN at all! Observations of three of the four GC PNe show them to have peculiar characteristics, possibly indicative of a binary/merger origin. In particular two of the three observed GC PNe have masses which correspond to main sequence masses ~2-3 times the clusters’ turn-off masses, suggesting mergers of two, or even three stars have taken place. One of the three observed PNe is H-deficient, a characteristic exhibited by only 5 out of hundreds of field PNe. H-deficient PNe have been associated with binarity. As usual, not all parameters for these three PNe are clean indications of their binary origin. In an approved cycle 15 ACS/WFI proposal we asked to obtain observations of the only GC PN that has never been observed before at high resolution and whose central star has never been detected, as well as of the one H-deficient GC PN for which only low-quality WFPC2 images exist. When ACS stopped working we moved part of the observations to WFPC2. With this proposal we ask to complete our project, by obtaining two ACS/WFI images that could not be efficiently taken with WFPC2. These objects could tip the balance toward a binary interpretation for the GC PNe or make us seriously reconsider our understanding of stellar evolution in old populations.
NIC2/WFC3/IR 11548
Infrared Imaging of Protostars in the Orion A Cloud: The Role of Environment in Star Formation
We propose NICMOS and WFC3/IR observations of a sample of 252 protostars identified in the Orion A cloud with the Spitzer Space Telescope. These observations will image the scattered light escaping the protostellar envelopes, providing information on the shapes of outflow cavities, the inclinations of the protostars, and the overall morphologies of the envelopes. In addition, we ask for Spitzer time to obtain 55-95 micron spectra of 75 of the protostars. Combining these new data with existing 3.6 to 70 micron photometry and forthcoming 5-40 micron spectra measured with the Spitzer Space Telescope, we will determine the physical properties of the protostars such as envelope density, luminosity, infall rate, and outflow cavity opening angle. By examining how these properties vary with stellar density (i.e. clusters vs. groups vs. isolation) and the properties of the surrounding molecular cloud; we can directly measure how the surrounding environment influences protostellar evolution, and consequently, the formation of stars and planetary systems. Ultimately, this data will guide the development of a theory of protostellar evolution.
STIS/CC/MA 11516
COS-GTO: Cold ISM
With the COS, we will be able to observe interstellar spectra in a new regime, translucent clouds, for atomic, ionic, and molecular lines and bands, and extinction curves. The COS will allow us to observe stars with total visual extinctions up to 10 magnitudes, and the grain size indicator Rv up to 4.5. In translucent clouds we expect to see the transition from neutral and ionized carbon to mostly C I, and then from there, we should expect to see carbon increasingly locked up in molecular form, as CO. Other species are expected to make similar transitions, so we should find detectable abundances of molecules such as H2O, OH, CS, CH2, SiO, and others; also, lower ionization fractions of the metallic elements – and higher depletions of those elements as well. Given that we expect to find higher depletions, we should see an altered grain size distribution, which may show up in the extinction curves, probably as lower far-UV extinction than in diffuse clouds. Finally, we will search for neutral PAHs in absorption, as diffuse bands in the UV, paralleling the optical DIBs (which are thought by some scientists to be formed by singly-ionized PAHs). In translucent clouds, models show that the PAHs will be neutral, not in cationic form.
NIC3/WFC3/IR 11149
Characterizing the Stellar Populations in Lyman-Alpha Emitters and Lyman Break Galaxies at 5.7
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
12218 – GSAcq(2,1,1) 073/02:24z failed with search radius limit on FGS 1 and FGS 2 & REAcq(2,1,1) at 073/04:00z failed with SRL exceeded on FGS 1.
Observations affected: ACS 60-68 & WFC3 229-232 Proposal ID#12020
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 20 19
FGS REAcq 27 26
OBAD with Maneuver 15 15
SIGNIFICANT EVENTS: (None)
