NASA Hubble Space Telescope Daily Report # 4513
HUBBLE SPACE TELESCOPE DAILY REPORT # 4513
Continuing to collect World Class Science
PERIOD COVERED: UT December 21,22,23,24,25, 2007 (DOY 355,356,357,358,359)
OBSERVATIONS SCHEDULED
NIC1/NIC2/NIC3 8795
NICMOS Post-SAA calibration – CR Persistence Part 6
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.
NIC1/NIC2/NIC3 11330
NICMOS Cycle 16 Extended Dark
This takes a series of Darks in parallel to other instruments.
ACS/SBC 11220
Mapping the FUV Evolution of Type IIn Supernovae
We will use the PR110L prism on the SBC of ACS to map the FUV evolution of Type IIn supernovae {SNe}. The main goal of this proposal is to measure the FUV continuum, Ly-a emission line flux, and their evolution to {1} quantify and interpret Type IIn SN transient event detections at high redshift and {2} dramatically improve current high redshift Type IIn selection criteria. We show that the inherent properties of Type IIn SNe facilitate high redshift detection. We will observe the rest-frame FUV of a sample of eight 0.02 < z < 0.33 Type IIn SNe to directly measure the survival of Ly-alpha photons in low to intermediate redshift Type IIn SNe environments and extrapolate the results to high redshift. We will calibrate relationships such as FUV luminosity vs. emission line flux and measure emission line evolution vs. FUV light evolution. The intent is to categorize and improve the utility of Type IIn SNe.
NIC2 11219
Active Galactic Nuclei in nearby galaxies: a new view of the origin of the radio-loud radio- quiet dichotomy?
Using archival HST and Chandra observations of 34 nearby early-type galaxies {drawn from a complete radio selected sample} we have found evidence that the radio-loud/radio-quiet dichotomy is directly connected to the structure of the inner regions of their host galaxies in the following sense: [1] Radio-loud AGN are associated with galaxies with shallow cores in their light profiles [2] Radio-quiet AGN are only hosted by galaxies with steep cusps. Since the brightness profile is determined by the galaxy’s evolution, through its merger history, our results suggest that the same process sets the AGN flavour. This provides us with a novel tool to explore the co-evolution of galaxies and supermassive black holes, and it opens a new path to understand the origin of the radio-loud/radio-quiet AGN dichotomy. Currently our analysis is statistically incomplete as the brightness profile is not available for 82 of the 116 targets. Most galaxies were not observed with HST, while in some cases the study is obstructed by the presence of dust features. We here propose to perform an infrared NICMOS snapshot survey of these 82 galaxies. This will enable us to i} test the reality of the dichotomic behaviour in a substantially larger sample; ii} extend the comparison between radio-loud and radio-quiet AGN to a larger range of luminosities.
FGS 11211
An Astrometric Calibration of Population II Distance Indicators
In 2002 HST produced a highly precise parallax for RR Lyrae. That measurement resulted in an absolute magnitude, M{V}= 0.61+/-0.11, a useful result, judged by the over ten refereed citations each year since. It is, however, unsatisfactory to have the direct, parallax-based, distance scale of Population II variables based on a single star. We propose, therefore, to obtain the parallaxes of four additional RR Lyrae stars and two Population II Cepheids, or W Vir stars. The Population II Cepheids lie with the RR Lyrae stars on a common K-band Period-Luminosity relation. Using these parallaxes to inform that relationship, we anticipate a zero-point error of 0.04 magnitude. This result should greatly strengthen confidence in the Population II distance scale and increase our understanding of RR Lyrae star and Pop II Cepheid astrophysics.
NIC3 11195
Morphologies of the Most Extreme High-Redshift Mid-IR-luminous Galaxies II: The `Bump’ Sources
The formative phase of some of the most massive galaxies may be extremely luminous, characterized by intense star- and AGN-formation. Till now, few such galaxies have been unambiguously identified at high redshift, and thus far we have been restricted to studying the low-redshift ultraluminous infrared galaxies as possible analogs. We have recently discovered a sample of objects which may indeed represent this early phase in galaxy formation, and are undertaking an extensive multiwavelength study of this population. These objects are optically extremely faint {R>26} but nevertheless bright at mid-infrared wavelengths {F[24um] > 0.5 mJy}. Mid-infrared spectroscopy with Spitzer/IRS reveals that they have redshifts z~2, implying luminosities ~1E13 Lsun. Their mid-IR SEDs fall into two broad, perhaps overlapping, categories. Sources with brighter F[24um] exhibit power-law SEDs and SiO absorption features in their mid-IR spectra characteristic of AGN, whereas those with fainter F[24um] show a “bump” characteristic of the redshifted 1.6um peak from a stellar population, and PAH emission characteristic of starformation. We have begun obtaining HST images of the brighter sources in Cycle 15 to obtain identifications and determine kpc-scale morphologies for these galaxies. Here, we aim to target the second class {the “bump” sources} with the goal of determining if these constitute morphologically different objects, or simply a “low-AGN” state of the brighter class. The proposed observations will help us determine whether these objects are merging systems, massive obscured starbursts {with obscuration on kpc scales!} or very reddened {locally obscured} AGN hosted by intrinsically low-luminosity galaxies.
WFPC2 11187
A Deep Search for Martian Dust Rings
It has been long suspected that Mars is encircled by two faint rings of dust, one originating from each of its moons Phobos and Deimos. Similar dust rings are associated with many of the small, inner moons orbiting Jupiter, Saturn, Uranus and Neptune. On December 31, 2007, Earth will pass through Mars’ equatorial plane just a week after its December 24 opposition, providing an exceedingly rare opportunity to image the rings under nearly ideal viewing geometry. The next equivalent viewing opportunity occurs in 2022. Using the Wide Fields of WFPC2 and a highly optimized observing plan, we expect to be able to detect rings with edge-on reflectivities of ~ 10^-8, which is at or below the level where most dynamicists expect rings to be visible. This is a factor of 10-30 more sensitive than the detection limit we achieved during a slightly inferior viewing opportunity in 2001. The rings have been predicted to show some interesting dynamical properties, including large asymmetries and inclinations. A positive detection will test these predictions, serving as an effective test of dynamical models developed to account for the properties of other faint planetary rings as well. With such a stringent limit, even a negative result will be of considerable interest, challenging dynamicists to explain the remarkably low density of dust within the Martian system.
WFPC2 11178
Probing Solar System History with Orbits, Masses, and Colors of Transneptunian Binaries
The recent discovery of numerous transneptunian binaries {TNBs} opens a window into dynamical conditions in the protoplanetary disk where they formed as well as the history of subsequent events which sculpted the outer Solar System and emplaced them onto their present day heliocentric orbits. To date, at least 47 TNBs have been discovered, but only about a dozen have had their mutual orbits and separate colors determined, frustrating their use to investigate numerous important scientific questions. The current shortage of data especially cripples scientific investigations requiring statistical comparisons among the ensemble characteristics. We propose to obtain sufficient astrometry and photometry of 23 TNBs to compute their mutual orbits and system masses and to determine separate primary and secondary colors, roughly tripling the sample for which this information is known, as well as extending it to include systems of two near-equal size bodies. To make the most efficient possible use of HST, we will use a Monte Carlo technique to optimally schedule our observations.
WFPC2 11176
Location and the Origin of Short Gamma-Ray Bursts
During the past decade extraordinary progress has been made in determining the origin of long-duration gamma-ray bursts. It has been conclusively shown that these objects derive from the deaths of massive stars. Nonetheless, the origin of their observational cousins, short-duration gamma-ray bursts {SGRBs} remains a mystery. While SGRBs are widely thought to result from the inspiral of compact binaries, this is a conjecture. A number of hosts of SGRBs have been identified, and have been used by some to argue that SGRBs derive primarily from an ancient population {~ 5 Gyr}; however, it is not known whether this conclusion more accurately reflects selection biases or astrophysics. Here we propose to employ a variant of a technique that we pioneered and used to great effect in elucidating the origins of long-duration bursts. We will examine the degree to which SGRB locations trace the red or blue light of their hosts, and thus old or young stellar populations. This approach will allow us to study the demographics of the SGRB population in a manner largely free of the distance dependent selection effects which have so far bedeviled this field, and should give direct insight into the age of the SGRB progenitor population.
NC3 11165
The Radius of the “Super-Neptune” HD 149026b
Current measurements suggest that the transiting exoplanet HD 149026b is a “super- Neptune,” with an enormous heavy-element core. The existence of such a planet is a major challenge to planet formation theories. We propose to place the radius measurement on much firmer footing, by obtaining a NICMOS light curve with 0.4 mmag precision and 13 sec cadence. We will improve the radius measurement by a factor of 2.3, and more importantly, the result will be more robust because we will determine the stellar radius directly from the data. Numerous attempts to do this from the ground have failed.
NIC2 11155
Dust Grain Evolution in Herbig Ae Stars: NICMOS Coronagraphic Imaging and Polarimetry
We propose to take advantage of the sensitive coronagraphic capabilities of NICMOS to obtain multiwavelength coronagraphic imaging and polarimetry of primordial dust disks around young intermediate-mass stars {Herbig Ae stars}, in order to advance our understanding of how dust grains are assembled into larger bodies. Because the polarization of scattered light is strongly dependent on scattering particle size and composition, coronagraphic imaging polarimetry with NICMOS provides a uniquely powerful tool for measuring grain properties in spatially resolved circumstellar disks. It is widely believed that planets form via the gradual accretion of planetesimals in gas-rich, dusty circumstellar disks, but the connection between this suspected process and the circumstellar disks that we can now observe around other stars remains very uncertain. Our proposed observations, together with powerful 3-D radiative transfer codes, will enable us to quantitatively determine dust grain properties as a function of location within disks, and thus to test whether dust grains around young stars are in fact growing in size during the putative planet-formation epoch. HST imaging polarimetry of Herbig Ae stars will complement and extend existing polarimetric studies of disks around lower-mass T Tauri stars and debris disks around older main-sequence stars. When combined with these previous studies, the proposed research will help us establish the influence of stellar mass on the growth of dust grains into larger planetesimals, and ultimately to planets. Our results will also let us calibrate models of the thermal emission from these disks, a critical need for validating the properties of more distant disks inferred on the basis of spectral information alone.
WFPC2/NIC3 11144
Building on the Significant NICMOS Investment in GOODS: A Bright, Wide-Area Search for z>=7 Galaxies
One of the most exciting frontiers in observational cosmology has been to trace the buildup and evolution of galaxies from very early times. While hierarchical theory teaches us that the star formation rate in galaxies likely starts out small and builds up gradually, only recently has it been possible to see evidence for this observationally through the evolution of the LF from z~6 to z~3. Establishing that this build up occurs from even earlier times {z~7-8} has been difficult, however, due to the small size of current high-redshift z~7-8 samples — now numbering in the range of ~4-10 sources. Expanding the size of these samples is absolutely essential, if we are to push current studies of galaxy buildup back to even earlier times. Fortunately, we should soon be able to do so, thanks to ~50 arcmin**2 of deep {26.9 AB mag at 5 sigma} NICMOS 1.6 micron data that will be available over the two ACS GOODS fields as a result of one recent 180-orbit ACS backup program and a smaller program. These data will nearly triple the deep near-IR imaging currently available and represent a significant resource for finding and characterizing the brightest high-redshift sources — since high-redshift candidates can be easily identified in these data from their red z-H colours. Unfortunately, the red z-H colours of these candidates are not sufficient to determine that these sources are at z>=7, and it is important also to have deep photometry at 1.1 microns. To obtain this crucial information, we propose to follow up each of these z- H dropouts with NICMOS at 1.1 microns to determine which are at high redshift and thus significantly expand our sample of luminous, z>=7 galaxies. Since preliminary studies indicate that these candidates occur in only 30% of the NIC3 fields, our follow-up strategy is ~3 times as efficient as without this preselection and 9 times as efficient as a search in a field with no pre-existing data. In total, we expect to identify ~8 luminous z-dropouts and possibly ~2 z~10 J-dropouts as a result of this program, more than tripling the number currently known. The increased sample sizes are important if we are to solidify current conclusions about galaxy buildup and the evolution of the LF from z~8. In addition to the high redshift science, these deep 1.1 micron data would have significant value for many diverse endeavors, including {1} improving our constraints on the stellar mass density at z~7-10 and {2} doubling the number of galaxies at z~6 for which we can estimate dust obscuration.
WFPC2 11130
AGNs with Intermediate-mass Black Holes: Testing the Black Hole-Bulge Paradigm, Part II
The recent progress in the study of central black holes in galactic nuclei has led to a general consensus that supermassive {10^6-10^9 solar mass} black holes are closely connected with the formation and evolutionary history of large galaxies, especially their bulge component. Two outstanding issues, however, remain unresolved. Can central black holes form in the absence of a bulge? And does the mass function of central black holes extend below 10^6 solar masses? Intermediate-mass black holes {<10^6 solar masses}, if they exist, may offer important clues to the nature of the seeds of supermassive black holes. Using the SDSS, our group has successfully uncovered a new population of AGNs with intermediate-mass black holes that reside in low-luminosity galaxies. However, very little is known about the detailed morphologies or structural parameters of the host galaxies themselves, including the crucial question of whether they have bulges or not. Surprisingly, the majority of the targets of our Cycle 14 pilot program have structural properties similar to dwarf elliptical galaxies. The statistics from this initial study, however, are really too sparse to reach definitive conclusions on this important new class of black holes. We wish to extend this study to a larger sample, by using the Snapshot mode to obtain WFPC2 F814W images from a parent sample of 175 AGNs with intermediate-mass black holes selected from our final SDSS search. We are particularly keen to determine whether the hosts contain bulges, and if so, how the fundamental plane properties of the host depend on the mass of their central black holes. We will also investigate the environment of this unique class of AGNs.
WFPC2 11113
Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution
The discovery of binaries in the Kuiper Belt and related small body populations is powering a revolutionary step forward in the study of this remote region. Three quarters of the known binaries in the Kuiper Belt have been discovered with HST, most by our snapshot surveys. The statistics derived from this work are beginning to yield surprising and unexpected results. We have found a strong concentration of binaries among low-inclination Classicals, a possible size cutoff to binaries among the Centaurs, an apparent preference for nearly equal mass binaries, and a strong increase in the number of binaries at small separations. We propose to continue this successful program in Cycle 16; we expect to discover at least 13 new binary systems, targeted to subgroups where these discoveries can have the greatest impact.
NIC3 11107
Imaging of Local Lyman Break Galaxy Analogs: New Clues to Galaxy Formation in the Early Universe
We have used the ultraviolet all-sky imaging survey currently being conducted by the Galaxy Evolution Explorer {GALEX} to identify for the first time a rare population of low- redshift starbursts with properties remarkably similar to high-redshift Lyman Break Galaxies {LBGs}. These “compact UV luminous galaxies” {UVLGs} resemble LBGs in terms of size, SFR, surface brightness, mass, metallicity, kinematics, dust, and color. The UVLG sample offers the unique opportunity of investigating some very important properties of LBGs that have remained virtually inaccessible at high redshift: their morphology and the mechanism that drives their star formation. Therefore, in Cycle 15 we have imaged 7 UVLGs using ACS in order to 1} characterize their morphology and look for signs of interactions and mergers, and 2} probe their star formation histories over a variety of timescales. The images show a striking trend of small-scale mergers turning large amounts of gas into vigorous starbursts {a process referred to as dissipational or “wet” merging}. Here, we propose to complete our sample of 31 LBG analogs using the ACS/SBC F150LP {FUV} and WFPC2 F606W {R} filters in order to create a statistical sample to study the mechanism that triggers star formation in UVLGs and its implications for the nature of LBGs. Specifically, we will 1} study the trend between galaxy merging and SFR in UVLGs, 2} artificially redshift the FUV images to z=1-4 and compare morphologies with those in similarly sized samples of LBGs at the same rest-frame wavelengths in e.g. GOODS, UDF, and COSMOS, 3} determine the presence and morphology of significant stellar mass in “pre-burst” stars, and 4} study their immediate environment. Together with our Spitzer {IRAC+MIPS}, GALEX, SDSS and radio data, the HST observations will form a unique union of data that may for the first time shed light on how the earliest major episodes of star formation in high redshift galaxies came about. This proposal was adapted from an ACS HRC+WFC proposal to meet the new Cycle 16 observing constraints, and can be carried out using the ACS/SBC and WFPC2 without compromising our original science goals.
NIC3 11080
Exploring the Scaling Laws of Star Formation
As a variety of surveys of the local and distant Universe are approaching a full census of galaxy populations, our attention needs to turn towards understanding and quantifying the physical mechanisms that trigger and regulate the large-scale star formation rates {SFRs} in galaxies.
WFPC2 11079
Treasury Imaging of Star Forming Regions in the Local Group: Complementing the GALEX and NOAO Surveys
We propose to use WFPC2 to image the most interesting star-forming regions in the Local Group galaxies, to resolve their young stellar populations. We will use a set of filters including F170W, which is critical to detect and characterize the most massive stars, to whose hot temperatures colors at longer wavelengths are not sensitive. WFPC2’s field of view ideally matches the typical size of the star-forming regions, and its spatial resolution allows us to measure individual stars, given the proximity of these galaxies. The resulting H-R diagrams will enable studies of star-formation properties in these regions, which cover largely differing metallicities {a factor of 17, compared to the factor of 4 explored so far} and characteristics. The results will further our understanding of the star-formation process, of the interplay between massive stars and environment, the properties of dust, and will provide the key to interpret integrated measurements of star-formation indicators {UV, IR, Halpha} available for several hundreds more distant galaxies. Our recent deep surveys of these galaxies with GALEX {FUV, NUV} and ground-based imaging {UBVRI, Halpha, [OIII] and [SII]} provided the identification of the most relevant SF sites. In addition to our scientific analysis, we will provide catalogs of HST photometry in 6 bands, matched corollary ground-based data, and UV, Halpha and IR integrated measurements of the associations, for comparison of integrated star-formation indices to the resolved populations. We envisage an EPO component.
WFPC2 11070
WFPC2 CYCLE 15 Standard Darks – part II
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 11040
Geometric Distortion / Astrometry Closeout
These observations will serve as a final characterization of the geometric distortion and astrometric calibration. The Omega-Cen inner calibration field is used. Filters F300W, F555W, and F814W are observed at 5 roll angles spanning 180 degrees; F218W is observed at a single roll angle.
WFPC2 11024
WFPC2 CYCLE 15 INTERNAL MONITOR
This calibration proposal is the Cycle 15 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {both gain 7 and gain 15 — to test stability of gains and bias levels}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. These also provide raw data for generating annual super-bias reference files for the calibration pipeline.
FGS 11019
Monitoring FGS1r’s Interferometric Response as a Function of Spectral Color
This proposal uses FGS1r in Transfer mode to observe standard single stars of a variety of spectral types to obtain point source interferograms for the Transfer mode calibration library. In specific cases, the calibration star will also be observed in POS mode multiple times with the F583W and F5ND elements to provide the data to verify the stability of the cross filter calibration.
FGS 10928
Calibrating Cosmological Chronometers: White Dwarf Masses
We propose to use HST/FGS1R to determine White Dwarf {WD} masses. The unmatched resolving power of HST/FGS1R will be utilized to follow up four selected WD binary pairs. This high precision obtained with HST/FGS1R simply cannot be equaled by any ground based technique. This proposed effort complements that done by CoI Nelan in which a sample of WDs is being observed with HST/FGS1R. This proposal will dramatically increase the number of WDs for which dynamical mass measurements are possible, enabling a better calibration of the WD mass-radius relation, cooling curves, initial to final mass relations, and ultimately giving important clues to the star formation history of our Galaxy and the age of its disk as well as in other galaxies.
NIC3/WFPC2 10921
Tangential Velocities of Objects in the Orion Nebula and Locating the Embedded Outflow Sources.
The Orion Nebula is arguably the Rosetta Stone for studying a very young star cluster and how the radiation and outflowing plasma from its stars interact with ambient material. It has been the subject of numerous HST imaging studies, which means that there is good opportunity for determining tangential velocities by obtaining second epoch images during Cycle 15, which may be the last cycle for which the WFPC2 is available. These velocities in the plane-of-the-sky will allow us to determine the patterns of outflow from micro-jets smaller than the Solar System to jet driven shocks more than a parsec from their sources. Combined with radial velocities, we’ll obtain spatial velocities, which are critical to determining where the embedded sources are located that produce the numerous HH objects coming from the Orion-S and BN-KL regions. We’ll also be able to determine the physics that is operating in the LL Ori type of outflows {where a bipolar jet is being distorted by a slow wind coming from the nebula}. We will also be able to search for runaway stars caused by the disintegration of young multiple-star systems. All of this is possible because the long-time base of the WFPC2 and ACS observations allow a new level of astrometric precision to be obtained and to be done efficiently by making coordinated parallel observations with all images.
WFPC2 10915
ACS Nearby Galaxy Survey
Existing HST observations of nearby galaxies comprise a sparse and highly non-uniform archive, making comprehensive comparative studies among galaxies essentially impossible. We propose to secure HST’s lasting impact on the study of nearby galaxies by undertaking a systematic, complete, and carefully crafted imaging survey of ALL galaxies in the Local Universe outside the Local Group. The resulting images will allow unprecedented measurements of: {1} the star formation history {SFH} of a >100 Mpc^3 volume of the Universe with a time resolution of Delta[log{t}]=0.25; {2} correlations between spatially resolved SFHs and environment; {3} the structure and properties of thick disks and stellar halos; and {4} the color distributions, sizes, and specific frequencies of globular and disk clusters as a function of galaxy mass and environment. To reach these goals, we will use a combination of wide-field tiling and pointed deep imaging to obtain uniform data on all 72 galaxies within a volume-limited sample extending to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the wide-field imaging will cover out to ~1.5 times the optical radius and will reach photometric depths of at least 2 magnitudes below the tip of the red giant branch throughout the limits of the survey volume. One additional deep pointing per galaxy will reach SNR~10 for red clump stars, sufficient to recover the ancient SFH from the color-magnitude diagram. This proposal will produce photometric information for ~100 million stars {comparable to the number in the SDSS survey} and uniform multi- color images of half a square degree of sky. The resulting archive will establish the fundamental optical database for nearby galaxies, in preparation for the shift of high- resolution imaging to the near-infrared.
WFPC2 10873
The Radio-quiet Jet Flow in Markarian 34
The properties of AGN jet flows are notoriously difficult to ascertain. We are currently studying jets in Seyferts by combining emission-line diagnostics with radio observations. We have devised a method of analysis which — with only modest and reasonable assumptions — leads to a physical description of the jet flow: its mass, momentum and energy flux, along with its density, velocity and Mach number. We have applied this method to a rich dataset on Markarian 78 and discovered that its jet is very weak, slow, and dense relative to the kind of jets found in radio loud AGN {Whittle \& Wilson 2004, Whittle et al 2005, 2006}. Such a difference between radio quiet and radio loud jet flows would be a major result — if it were found to be generally true. We have more modest observations of a further six Seyferts with jets, but only one of these — Mkn 34 — approaches Mkn 78 as a clean enough case to allow our full analysis. Our existing VLA and STIS data are excellent, but the HST archive emission-line and continuum images are of poor quality and low resolution. We are requesting just 3 orbits to obtain higher S/N images at high resolution {ACS/HRC} in [OIII] 5007, [OII] 3727, green and red continuum, bringing the total dataset up to a par with that of Mkn 78. We will then be able to apply our full analysis to determine the nature of the jet flow in this second radio quiet AGN.
NIC2 10854
Coronagraphic Imaging of Bright New Spitzer Debris Disks II.
Fifteen percent of bright main sequence stars possess dusty circumstellar debris disks revealed by far-infrared photometry. These disks are signposts of planetary systems: collisions among larger, unseen parent bodies maintain the observed dust population against losses to radiation pressure and P-R drag. Images of debris disks at optical, infrared, and millimeter wavelengths have shown central holes, rings, radial gaps, warps, and azimuthal asymmetries which indicate the presence of planetary mass perturbers. Such images provide unique insights into the structure and dynamics of exoplanetary systems. Relatively few debris disks have been spatially resolved. Only thirteen have ever been resolved at any wavelength, and at wavelengths < 10 microns {where subarcsec resolution is available}, only ten. Imaging of many other debris disk targets has been attempted with various HST cameras/coronagraphs and adaptive optics, but without success. The key property which renders a debris disk observable in scattered light is its dust optical depth. The ten disks imaged so far all have a dust excess luminosity >~ 0.01% that of the central star; no disks with smaller optical depths have been detected. Most main sequence stars known to meet this requirement have already been observed, so future progress in debris disk imaging depends on discovering additional stars with large infrared excess. The Spitzer Space Telescope offers the best opportunity in 20 years to identify new examples of high optical depth debris disk systems. We propose to complete ACS coronagraphic imaging follow up of bright, new debris disks discovered during the first two years of the Spitzer mission, by observing three additional targets in Cycle 15. Our goal is to obtain the first resolved images of these disks at ~3 AU resolution, define the disk sizes and orientations, and uncover disk substructures indicative of planetary perturbations. The results will open wider a window into the structure of planetary systems.
WFPC2 10812
Space Motions for the Draco and Sextans Dwarf Spheroidal Galaxies
We will use the powerful astrometric capabilities of HST to measure proper motions for the Draco and Sextans dwarf spheroidal galaxies that will yield tangential velocities accurate to about 30 km/s. These two galaxies are the last inside a galactocentric radius of 200~kpc without measured proper motions. Knowing their orbits is critical for our understanding of the low-luminosity satellites of the Milky Way. In particular they are critical for understanding why Ursa Minor has survived tidal disruption on its plunging orbit and how Carina formed a large intermediate-age stellar population despite its small mass.
WFPC2 10787
Modes of Star Formation and Nuclear Activity in an Early Universe Laboratory
Nearby compact galaxy groups are uniquely suited to exploring the mechanisms of star formation amid repeated and ongoing gravitational encounters, conditions similar to those of the high redshift universe. These dense groups host a variety of modes of star formation, and they enable fresh insights into the role of gas in galaxy evolution. With Spitzer mid-IR observations in hand, we have begun to obtain high quality, multi-wavelength data for a well- defined sample of 12 nearby {<4500km/s} compact groups covering the full range of evolutionary stages. Here we propose to obtain sensitive BVI images with the ACS/WFC, deep enough to reach the turnover of the globular cluster luminosity function, and WFPC2 U-band and ACS H-alpha images of Spitzer-identified regions hosting the most recent star formation. In total, we expect to detect over 1000 young star clusters forming inside and outside galaxies, more than 4000 old globular clusters in >40 giant galaxies {including 16 early-type galaxies}, over 20 tidal
features, approximately 15 AGNs, and intragroup gas in most of the 12 groups. Combining the proposed ACS images with Chandra observations, UV GALEX observations, ground-based H-alpha imaging, and HI data, we will conduct a detailed study of stellar nurseries, dust, gas kinematics, and AGN.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
11113 – Loss of Lock while LOS
HST lost fine lock on FGS 1 and 2 at 356/00:27:52. P4TAKDAT (Take Data Flag) went down at that time, causing four ACS 779 Status Buffer Messages (“Fold Mechanism Move Was Blocked”) to occur at 00:28:00, 00:37:54, 00:47:50 and 00:57:44. Upon acquisition of signal at 00:43:00 QF1STOPF was observed to be flagging.
11114 – GSacq (1,3,3) resulted in Fine Lock Back-up (1,0,1) using FGS 1
At 356/13:00:39, GSAcq (1,3,3) scheduled from 356/12:57:09 – 13:04:24 had failed to Fine Lock Back-up (1,0,1) using FGS 1, due to stop flags QF3STOPF and QSTOP on FGS 3. Pre-acquisition OBAD #1 had an RSS value of 472.38 arc seconds. Pre-acquisition OBAD #2 had an RSS value of 24.87 arc seconds. Post-acquisition OBAD Map had an RSS value of 11.01 arc seconds.
11116 – REacq (1,3,1) fine lock backup on FGS 1
REACQ(1,3,1) at 357/06:26:02 acquired in fine lock backup on FGS 1 only, with QF3STOPF and QSTOP flags set on FGS 3. No other flags were seen. Initial GSACQ(1,3,1) at 03:15:01 and REACQ at 04:50:03 were successful.
11117 – GSacq (1,2,2) failed, Search Radius Limit exceeded on FGS 1 @ 358/0320z
GSACQ(1,2,2) at 03:20:53 failed with search radius limit exceeded on FGS 1 at 03:26:40. One “A05” ESB message (FGS Coarse Track failed- search Radius Limit exceeded) was received at 03:26:50.
OBADs prior to GSACQ had RSS errors of 1653.05 and 27.31 arcseconds, OBAD map following GSACQ at 03:28:57 had RSS error of 572.46 arcseconds.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE
TIMES
FGS GSacq 40 39
FGS REacq 30 30
OBAD with Maneuver 140 139
LOSS of LOCK @ 356/0027z
SIGNIFICANT EVENTS: (None)
