NASA Hubble Space Telescope Daily Report #4981
HUBBLE SPACE TELESCOPE DAILY REPORT #4981
Continuing to Collect World Class Science
PERIOD COVERED: 5am November 27 – 5am November 30, 2009 (DOY 331/10:00z-334/10:00z)
OBSERVATIONS SCHEDULED
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 11924
WFC3/UVIS External and Internal CTE Monitor
CCD detector Charge Transfer Inefficiency (CTI)-induced losses in photometry and astrometry will be measured using observations of the rich open cluster NGC6791 and with the EPER (Extended Pixel Edge Response) method using tungsten lamp flat field exposures. Although we do not expect to see CTE effects at the outset of Cycle 17, this CTE monitoring program is the first of a multi-cycle program to monitor and establish CTE-induced losses with time. We expect to measure CTE effects with a precision comparable to the ACS measurements.
WFC3/IR 11920
WFC3 IR Image Quality
The IR imaging performance over the detector will be assessed periodically (every 4 months) in two passbands to check for image stability. The field around star 58 in the open cluster NGC188 is the chosen target because it is sufficiently dense to provide good sampling over the FOV while providing enough isolated stars to permit accurate PSF (point spread function) measurement. It is available year-round and used previously for ACS image quality assessment. The field is astrometric, and astrometric guide stars will be used, so that the plate scale and image orientation may also be determined if necessary (as in SMOV proposals 11437 and 11443). Full frame images will be obtained at each of 4 POSTARG offset positions designed to improve sampling over the detector in F098M, F105W, and F160W. The PSFs will be sampled at 4 positions with subpixel shifts in filters F164N and F127M.
This proposal is a periodic repeat (once every 4 months) of the visits in SMOV proposal 11437 (activity ID WFC3-24). The data will be analyzed using the code and techniques described in ISR WFC3 2008-41 (Hartig). Profiles of encircled energy will be monitored and presented in an ISR. If an update to the SIAF is needed, (V2, V3) locations of stars will be obtained from the Flight Ops. Sensors and Calibrations group at GSFC, the (V2, V3) of the reference pixel and the orientation of the detector will be determined by the WFC3 group, and the Telescopes group will update and deliver the SIAF to the PRDB branch.
The specific PSF metrics to be examined are encircled energy for aperture diameter 0.25, 0.37, and 0.60 arcsec, FWHM, and sharpness. (See ISR WFC3 2008-41 tables 2 and 3 and preceding text.) ~20 stars distributed over the detector will be measured in each exposure for each filter. The mean, rms, and rms of the mean will be determined for each metric. The values determined from each of the 4 exposures per filter within a visit will be compared to each other to see to what extent they are affected by “breathing”. Values will be compared from visit to visit, starting with the values obtained during SMOV after the fine alignment has been performed, to see if the measures of the compactness of the PSF indicate degradation over time. The analysis will be repeated for stars on the inner part of the detector and stars on the outer part of the detector to check for differential degradation of the PSF.
As an example of the analysis, one can examine the sharpness of the F160W PSF exposures made during thermal vacuum testing (ISR WFC3 2008-41). To compare two samples, one can define the PSFs on each half of the detector (lower and upper) as a sample (with 7 and 8 PSFs, respectively). The mean, rms, and rms of the mean sharpness are 0.0826, 0.0067, and 0.0027 for one half, and 0.0773, 0.0049, and 0.0019 for the other. The difference of the means is 0.0053 and the statistical error in that difference is 0.0033, so the difference is not significant.
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).
ACS/WFC3 11879
CCD Daily Monitor (Part 1)
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 352 orbits (22 weeks) from 31 August 2009 to 31 January 2010.
FGS 11875
Monitoring FGS2R2 Distortion and Alignment After SMOV4
This proposal monitors changes in the FGS2R2 distortion and alignment after SMOV4 by observing selected stars in M35 in Position mode. Data from each epoch are compared to track changes in FGS2R2. When the rate of change becomes sufficiently slow, FGS2R2 will be cleared for a mini-OFAD and FGS-FGS alignment calibration (carried out in another phase 2 proposal).
STIS/CCD/MA1/MA2 11866
Echelle Grating Blaze Function Zero Points
We will observe the flux standard G191B2B, obtaining echelle spectra in all primary and intermediate wavelength settings. While this was done in cycle 10 (8915), the echelle blaze shift has proved to depend sensitively on side of operation, time and the exact MSM positioning. We therefore believe it is important to obtain a complete set of post- repair data at default MSM position to allow a comprehensive solution for the echelle blaze shifts on a repaired side 2.
STIS/CCD/MA1/MA2 11860
MAMA Spectroscopic Sensitivity and Focus Monitor
The purpose of this proposal is to monitor the sensitivity of each MAMA grating mode to detect any change due to contamination or other causes, and to also monitor the STIS focus in a spectroscopic and an imaging mode.
STIS/CCD 11846
CCD Bias Monitor-Part 1
The purpose of this proposal is to 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 11844
CCD Dark Monitor Part 1
The purpose of this proposal is to monitor the darks for the STIS CCD.
FGS 11788
The Architecture of Exoplanetary Systems
Are all planetary systems coplanar? Concordance cosmogony makes that prediction. It is, however, a prediction of extrasolar planetary system architecture as yet untested by direct observation for main sequence stars other than the Sun. To provide such a test, we propose to carry out FGS astrometric studies on four stars hosting seven companions. Our understanding of the planet formation process will grow as we match not only system architecture, but formed planet mass and true distance from the primary with host star characteristics for a wide variety of host stars and exoplanet masses.
We propose that a series of FGS astrometric observations with demonstrated 1 millisecond of arc per-observation precision can establish the degree of coplanarity and component true masses for four extrasolar systems: HD 202206 (brown dwarf+planet); HD 128311 (planet+planet), HD 160691 = mu Arae (planet+planet), and HD 222404AB = gamma Cephei (planet+star). In each case the companion is identified as such by assuming that the minimum mass is the actual mass. For the last target, a known stellar binary system, the companion orbit is stable only if coplanar with the AB binary orbit.
ACS/WFC3 11735
The LSD Project: Dynamics, Merging and Stellar Populations of a Sample of Well- Studied LBGs at z~3
A large observational effort with the ground-based ESO/VLT telescopes allowed us to obtain deep, spatially-resolved, near-IR spectra of complete sample of 11 Lyman-Break Galaxies at z~3.1. These observations were used to obtain, for the first time, the metallicity and the dynamical properties of a sample of objects that, albeit small, is representative of the total population of the LBGs. We propose to use HST to obtain high-resolution optical and near-IR images of this sample of LBGs in order to study the broad-band morphology and the stellar light distribution of these galaxies. These images, exploiting the superior spatial resolution of HST images and the low- background : 1- will allow a precise measure of the dynamical mass from the velocity field derived with spectroscopy; 2- will permit a comparison of the distribution of star formation (from the line emission) with the underlying stellar population, and, 3- will be used to check if the complex velocity field and the multiple line-emitting regions detected in most targets can be ascribed to on-going mergers. This accurate study will shed light on a number of unsolved problems still affecting the knowledge of the LBGs.
WFC3/ACS/UVIS 11724
Direct Age Determination of the Local Group dE Galaxies NGC 147 and NGC 185
The origin of dwarf elliptical (dE) galaxies remains a mystery and the dE galaxies of the Local Group provide the best opportunity to study this galaxy class in detail. We propose to obtain ACS photometry of main sequence turnoff stars in the M31 dE satellites NGC 147 and NGC 185. Because these galaxies have little to no stars younger than 1 Gyr, resolving the main sequence turnoff is required to directly quantify their star formation histories. NGC 147 and NGC 185 are the only two dEs for which a clean measurement is feasible with the HST. This proposal was accepted in Cycle 15, but little data were taken before the failure of ACS. The main sequence turnoffs of NGC 147 and NGC 185 are expected to be at an apparent magnitude of V=29; we request F606W/F814W imaging one half magnitude fainter than this limit (three magnitudes fainter than the deepest previous dE observations). Quantifying the ratio of old to intermediate-age stars will allow us to discriminate between competing models of dE formation. On-going Keck/DEIMOS spectroscopy of several hundred red giant stars in each of these two dE galaxies, coupled with dynamical modeling and spectral synthesis, will complement the ACS measurement by providing information on chemical abundance patterns, dark matter content and internal dynamics. The proposed ACS data will be the first to directly quantify the onset and duration of star formation episodes in dE galaxies, and will thereby form the cornerstone in what promises to be the most comprehensive study of this class of galaxies.
WFC3/UVIS/IR 11723
Imaging the Crab Nebula-Like Supernova Remnant 3C 58
The Galactic supernova remnant 3C 58 shares several important properties with the Crab Nebula. It possesses a young, rapidly spinning pulsar and an associated compact optical/IR synchrotron wind nebula. This makes 3C 58, along with the Crab and PSR B0540-69 in the LMC, only the third such PWN detected in the optical and IR. Also like the Crab, 3C58 has been associated with a historically reported `guest star’, in this case, the apparent SN of 1181 CE. Its optical nebulosity contains an unusually large fraction of shocked circumstellar material, with the remnant’s high-velocity, N-rich ejecta knots exhibiting a strong bi-polar expansion asymmetry.
Despite having a relatively extensive optical nebula, it is the only young and nearby Galactic SNR that has not yet been imaged by HST. However, some recent deep, high- resolution Gemini images show a surprising amount of fine-scale filament detail, revealing some peculiar optical emission morphologies. Here we propose a WFC3 imaging survey of 3C 58 in order to investigate: 1) the optical luminosity and emission efficiency of the remnant’s young, 65.7 ms pulsar PSR J0205+6449 thereby providing a rare testing of pulsar emission models, 2) the effect of the remnant’s expanding synchrotron nebula on the formation of Rayleigh-Taylor instabilities in its optical filaments like that observed so far only in the Crab through HST imaging, and 3) the fine-scale structure of 3C 58’s slow moving circumstellar and high-velocity SN ejecta and the morphological and distribution differences between them.
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.
ACS/WFC3 11599
Distances of Planetary Nebulae from SNAPshots of Resolved Companions
Reliable distances to individual planetary nebulae (PNe) in the Milky Way are needed to advance our understanding of their spatial distribution, birthrates, influence on galactic chemistry, and the luminosities and evolutionary states of their central stars (CSPN). Few PNe have good distances, however. One of the best ways to remedy this problem is to find resolved physical companions to the CSPN and measure their distances by photometric main-sequence fitting. We have previously used HST to identify and measure probable companions to 10 CSPN, based on angular separations and statistical arguments only. We now propose to use HST to re-observe 48 PNe from that program for which additional companions are possibly present. We then can use the added criterion of common proper motion to confirm our original candidate companions and identify new ones in cases that could not confidently be studied before. We will image the region around each CSPN in the V and I bands, and in some cases in the B band. Field stars that appear close to the CSPN by chance will be revealed by their relative proper motion during the 13+ years since our original survey, leaving only genuine physical companions in our improved and enlarged sample. This study will increase the number of Galactic PNe with reliable distances by 50 percent and improve the distances to Pne with previously known companions.
WFC3/UVIS 11594
A WFC3 Grism Survey for Lyman Limit Absorption at z=2
We propose to conduct a spectroscopic survey of Lyman limit absorbers at redshifts 1.8 < z < 2.5, using WFC3 and the G280 grism. This proposal intends to complete an approved Cycle 15 SNAP program (10878), which was cut short due to the ACS failure. We have selected 64 quasars at 2.3 < z < 2.6 from the Sloan Digital Sky Survey Spectroscopic Quasar Sample, for which no BAL signature is found at the QSO redshift and no strong metal absorption lines are present at z > 2.3 along the lines of sight. The survey has three main
observational goals. First, we will determine the redshift frequency dn/dz of the LLS over the column density range 16.0 < log(NHI) < 20.3 cm^-2. Second, we will measure the column density frequency distribution f(N) for the partial Lyman limit systems (PLLS) over the column density range 16.0 < log(NHI) < 17.5 cm^-2. Third, we will identify those sightlines which could provide a measurement of the primordial D/H ratio. By carrying out this survey, we can also help place meaningful constraints on two key quantities of cosmological relevance. First, we will estimate the amount of metals in the LLS using the f(N), and ground based observations of metal line transitions. Second, by determining f(N) of the PLLS, we can constrain the amplitude of the ionizing UV background at z~2 to a greater precision. This survey is ideal for a snapshot observing program, because the on-object integration times are all well below 30 minutes, and follow-up observations from the ground require minimal telescope time due to the QSO sample being bright. WFC3/UVIS 11583 The Star Formation Rate In Nearby Elliptical Galaxies Small amounts of star formation in normal elliptical galaxies are suggested by several results: some surprisingly young ages from optical line-index dating; cooling X-ray gas; and mid-IR dust emission. Previously, it was difficult to detect low levels of star formation, but UV imaging with WFPC3 will permit us to conclusively identify individual O/B stars in nearby normal ellipticals by their UV colors and magnitudes. This technique is orders of magnitude more sensitive than previous methods, allowing detections of star formation to levels of 1E-4 Msolar/yr. Proof of concept is provided by a very long UV ACS observation of M87 that revealed many O/B stars. We propose observations of four normal ellipticals where recent star formation is likely. This will yield their star formation rates and the locations of such activity. WFC3/UVIS 11577 Opening New Windows on the Antennae with WFC3 We propose to use WFC3 to provide key observations of young star clusters in “The Antennae” (NGC4038/39). Of prime importance is the WFC3’s ability to push the limiting UV magnitude FIVE mag deeper than our previous WFPC2 observations. This corresponds to pushing the limiting cluster mass from ~10**5 to ~10**3 solar masses for cluster ages ~10**8 yrs. In addition, the much wider field of view of the WFC3 IR channel will allow us to map out both colliding disks rather than just the Overlap Region between them. This will be especially important for finding the youngest clusters that are still embedded in their placental cocoons. The extensive set of narrow-band filters will provide an effective means for determining the properties of shocks, which are believed to be a primary triggering mechanism for star formation. We will also use ACS in parallel with WFC3 to observe portions of both the northern and southern tails at no additional orbital cost. Finally, one additional primary WFC3 orbit will be used to supplement exisiting HST observations of the star-forming “dwarf” galaxy at the end of the southern tail. Hence, when completed we will have full UBVI + H_alpha coverage (or more for the main galaxy) of four different environments in the Antennae. In conjunction with the extensive multi-wavelength database we have collected (both HST and ground based) these observations will provide answers to fundamental questions such as: How do these clusters form and evolve? How is star formation triggered? How do star clusters affect the local and global ISM, and the evolution of the galaxy as a whole? The Antennae galaxies are the nearest example of a major disk–disk merger, and hence may represent our best chance for understanding how mergers form tremendous numbers of clusters and stars, both in the local universe and during galaxy assembly at high redshift. WFC3/UVIS 11565 A Search for Astrometric Companions to Very Low-Mass, Population II Stars We propose to carry out a Snapshot search for astrometric companions in a subsample of very low-mass, halo subdwarfs identified within 120 parsecs of the Sun. These ultra-cool M subdwarfs are local representatives of the lowest-mass H burning objects from the Galactic Population II. The expected 3-4 astrometric doubles that will be discovered will be invaluable in that they will be the first systems from which gravitational masses of metal-poor stars at the bottom of the main sequence can be directly measured. 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. FLIGHT OPERATIONS SUMMARY: Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.) HSTARS: #12109 GSAcq(1,2,1) @331/21:48:17z resulted in FL backup (2,0,2) @331/21:50z Observations possibly affected: WFC3 #175 Proposal #11565, WFC3 #176 Proposal #11908. COMPLETED OPS REQUEST: (None) COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 23 23
FGS REAcq 23 23
OBAD with Maneuver 19 19
SIGNIFICANT EVENTS: (None)
