NASA Hubble Space Telescope Daily Report #4137
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science DAILY REPORT # 4137
PERIOD COVERED: UT June 16,17,18 2006 (DOY 167,168,169)
OBSERVATIONS SCHEDULED
NIC1/NIC2/NIC3 8793
NICMOS Post-SAA calibration – CR Persistence Part 4
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.
ACS/HRC/WFC 10758
ACS CCDs daily monitor
This program consists of a set of basic tests to monitor, the read noise, the development of hot pixels and test for any source of noise in ACS CCD detectors. The files, biases and dark will be used to create reference files for science calibration. This programme will be for the entire lifetime of ACS. Changes from cycle 13:- The default gain for WFC is 2 e-/DN. As before bias frames will be collected for both gain 1 and gain 2. Dark frames are acquired using the default gain {2}. This program cover the period May, 31 2006- Oct, 1-2006. The first half of the program has a different proposal number: 10729.
ACS/WFC/NIC3 10632
Searching for galaxies at z>6.5 in the Hubble Ultra Deep Field
We propose to obtain deep ACS {F606W, F775W, F850LP} imaging in the area of the original Hubble Ultra Deep Field NICMOS parallel fields and – through simultaneous parallel observations – deep NICMOS {F110W, F160W} imaging of the ACS UDF area. Matching the extreme imaging depth in the optical and near-IR bands will result in seven fields with sufficiently sensitive multiband data to detect the expected typical galaxies at z=7 and 8. Presently no such a field exist. Our combined optical and near-IR ultradeep fields will be in three areas separated by about 20 comoving Mpc at z=7. This will allow us to give a first assessment of the degree of cosmic variance. If reionization is a process extending over a large redshift interval and the luminosity function doesn’t evolve strongly beyond z=6, these data will allow us to identify of the order of a dozen galaxies at 6.5
WFPC2 10631
Intermediate-Age Globular Clusters in M31
We propose deep ACS/WFC imaging of four halo M31 globular clusters in order to derive their horizontal branch morphologies. Our spectroscopic investigation of their integrated light identifies them as members of an intermediate-age population of globular clusters in M31. Since our spectroscopic results are based on the analysis of Balmer absorption lines, we need to secure our results against an artificial juvenation due to extreme horizontal branch morphologies. The proposed observations will allow a clear-cut answer to the question of whether spectroscopically derived intermediate-age estimates are due to genuinely younger ages or are the result of anomalously hot horizontal branch morphologies. Either way, our results will have important implications for spectroscopically derived ages and metallicities of distant stellar populations. Because of the high spatial resolution of the proposed ACS/WFC observations we will also derive accurate surface brightness profiles of our target globular clusters and investigate the influence of stellar density on horizontal branch morphology. Moreover, together with deep parallel WFPC2 fields we will study the metallicity dispersion of the background stellar population in M31 as a function of galactocentric radius.
ACS/WFC 10626
A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9
We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy clusters at 0.3 < z < 0.9 from the Red Sequence Cluster Survey {RCS}. An examination of the galaxian light in the brightest cluster galaxies, coupled with a statistical analysis of the strong-lensing properties of the sample, will allow us to contrain the evolution of both the baryonic and dark mass in cluster cores, over an unprecedented redshift range and sample size. In detail, we will use the high- resolution ACS images to measure the metric {10 kpc/h} luminosity and morphological disturbances around the brightest clusters galaxies, in order to calibrate their accretion history in comparison to recent detailed simulations of structure formation in cluster cores. These images will also yield a well-defined sample of arcs formed by strong lensing by these clusters; the frequency and detailed distribution {size, multiplicity, redshifts} of these strong lens systems sets strong constraints on the total mass content {and its structure} in the centers of the clusters. These data will also be invaluable in the study of the morphological evolution and properties of cluster galaxies over a significant redshift range. These analyses will be supported by extensive ongoing optical and near-infrared imaging, and optical spectroscopy at Magellan, VLT and Gemini telescopes, as well as host of smaller facilities.
ACS/HRC 10606
Ultraviolet Snapshots of 3CR Radio Galaxies
Radio galaxies are an important class of extragalactic objects: they are one of the most energetic astrophysical phenomena and they provide an exceptional probe of the evolving Universe, lying typically in high density regions but well-represented across a wide redshift range. In earlier Cycles we carried out extensive HST observations of the 3CR sources in order to acquire a complete and quantitative inventory of the structure, contents and evolution of these important objects. Amongst the results, we discovered new optical jets, dust lanes, face-on disks with optical jets, and revealed point-like nuclei whose properties support FR-I/BL Lac unified schemes. Here, we propose to obtain ACS NUV images of 3CR sources with z<0.3 as a major enhancement to an already superb dataset. We aim to reveal dust in galaxies, regions of star and star cluster formation frequently associated with dust and establish the physical characteristics of the dust itself. We will measure frequency and spectral energy distributions of point-like nuclei, seek spectral turnovers in known synchrotron jets and find new jets. We will strongly test unified AGN schemes and merge these data with existing X-ray to radio observations for significant numbers of both FR-I and FR-II sources. The resulting database will be an incredibly valuable resource to the astronomical community for years to come.
ACS/HRC 10589
The highest redshift Einstein ring: probing a dark matter halo at z=1 and galaxy morphology at z=3.8
The occurence of nearly complete Einstein rings is very low, but their importance cannot be overstated : in comparison with configurations which have a few images, Einstein rings provide a full characterisation of the dark matter halo when combined with measures of the velocity dispersion gradient in the lens. The projected gravitational potential is vastly constrained by the polar information given by the shape of the ring at different position angles. Our discovery of the highest redshift Einstein ring so far, a configuration where the lens is an elliptical galaxy at z=0.986 and the source a post-starburst Lyman break galaxy at z=3.77, yields several intriguing results. The modelling of the ring, which streches some 260 degrees around the lens, points to a very slow evolution in the mass-to-light ratio, as indicated by its position with respect to the fundamental plane of nearby ellipticals. This is at odds with the results obtained by the few lenses existing at this redshift. The M/L ratio within the effective radius is consistent with the one produced by stellar populations, indicating that the dark matter is not dominant at this radius. To fully characterise the dark matter halo of this unique elliptical at a look-back time of 50% of the current age of the universe, we require both a measure of the gradient in velocity dispersion and a high-resolution image of the ring. The former will be measured by our forthcoming VLT medium-resolution spectroscopy, while the later can only be provided by the ACS onboard HST. The presence of a counter-image which is radially elongated, combined with the shape of the main ring will lead to the first reconstructed projected potential of an isolated dark halo at z=1, with unprecedented accuracy. In addition, the exquisite image quality provided by the ACS will allow us to reconstruct the imaged source, providing the first ever high-resolution morphology of a Lyman-break galaxy at z=3.77.
ACS/WFC 10587
Measuring the Mass Dependence of Early-Type Galaxy Structure
We propose two-color ACS-WFC Snapshot observations of a sample of 118 candidate early- type gravitational lens galaxies. Our lens-candidate sample is selected to yield {in combination with earlier results} an approximately uniform final distribution of 40 early-type strong lenses across a wide range of masses, with velocity dispersions {a dynamical proxy for mass} ranging from 125 to 300 km/s. The proposed program will deliver the first significant sample of low-mass gravitational lenses. All of our candidates have known lens and source redshifts from Sloan Digital Sky Survey data, and all are bright enough to permit detailed photometric and stellar- dynamical observation. We will constrain the luminous and dark-matter mass profiles of confirmed lenses using lensed-image geometry and lens-galaxy structural/photometric measurements from HST imaging in combination with dynamical measurements from spatially resolved ground-based follow-up spectroscopy. Hence we will determine, in unprecedented detail, the dependence of early-type galaxy mass structure and mass-to-light ratio upon galaxy mass. These results will allow us to directly test theoretical predictions for halo concentration and star-formation efficiency as a function of mass and for the existence of a cuspy inner dark- matter component, and will illuminate the structural explanation behind the fundamental plane of early-type galaxies. The lens-candidate selection and confirmation strategy that we propose has been proven successful for high-mass galaxies by our Cycle 13 Snapshot program {10174}. The program that we propose here will produce a complementary and unprecedented lens sample spanning a wide range of lens-galaxy masses.
ACS/HRC 10556
Neutral Gas at Redshift z=0.5
Damped Lyman-alpha systems {DLAs} are used to track the bulk of the neutral hydrogen gas in the Universe. Prior to HST UV spectroscopy, they could only be studied from the ground at redshifts z>1.65. However, HST has now permitted us to discover 41 DLAs at z<1.65 in our previous surveys. Followup studies of these systems are providing a wealth of information about the evolution of the neutral gas phase component of the Universe. But one problem is that these 41 low-redshift systems are spread over a wide range of redshifts spanning nearly 70% of the age of the Universe. Consequently, past surveys for low-redshift DLAs have not been able to offer very good precision in any small redshift regime. Here we propose an ACS-HRC- PR200L spectroscopic survey in the redshift interval z=[0.37, 0.7] which we estimate will permit us to discover another 41 DLAs. This will not only allow us to double the number of low-redshift DLAs, but it will also provide a relatively high-precision regime in the low-redshift Universe that can be used to anchor evolutionary studies. Fortunately DLAs have high absorption equivalent width, so ACS-HRC-PR200L has high-enough resoultion to perform this proposed MgII-selected DLA survey.
ACS/WFC/HRC 10536
What Are Stalled Preplanetary Nebulae? An ACS SNAPshot Survey
Essentially all planetary nebulae {PNs} are aspherical, whereas the mass-loss envelopes of AGB stars are strikingly spherical. Our previous SNAPshot surveys of a morphologically unbiased sample of pre-planetary nebulae {PPNs} — objects in transition between the AGB and PN evolutionary phases — show that roughly half our observed targets are resolved, with bipolar or multipolar morphologies. Spectroscopic observations of our sample confirm that these objects have not yet evolved into planetary nebulae. Thus, the transformation from spherical to aspherical geometries has already fully developed by the time these dying stars have become PPNs. Although our current studies have yielded exciting results, they are limited in two important ways — {1} the number of well-resolved objects is still small {18}, and the variety of morphologies observed relatively multitudinous, hence no clear trends can yet be established between morphology and other source properties {e.g., near-IR, far-IR colors, stellar spectral type, envelope mass}, and {2} the current samples are strongly biased towards small PPNs, as inferred from their low 60-to-25 micron flux ratios [R{60/25}<1]. However, the prototype of objects with R{60/25}>1, the Frosty Leo Nebula, has a puzzlingly large post-AGB age {almost 10^4 yr} and a fairly cool central star, very different from the expectations of single-star stellar evolutionary models. A proposed, but still speculative, hypothesis for such objects is that the slow evolution of the central star is due to backflow of material onto the mass-losing star, retarding its evolution towards the PN phase. This hypothesis has significant consequences for both stellar and nebular evolution. We therefore propose a survey of PPNs with R{60/25}>1 which is heavily weighted towards the discovery of such “stalled PPNs”. Supporting kinematic observations using long-slit optical spectroscopy {with the Keck}, millimeter and radio interferometric observations {with OVRO, VLA & VLBA} are being undertaken. The results from this survey {together with our previous work} will allow us to draw general conclusions about the complex mass-outflow processes affecting late stellar evolution, and will provide crucial input for theories of post-AGB stellar evolution. Our survey will produce an archival legacy of long-standing value for future studies of dying stars.
NIC2/ACS/WFC/WFPC2 10532
Kinematics and morphology of the most massive field disk galaxies at z>1
We propose to obtain 1 orbit NIC-2 images of a sample of the 15 most massive galaxies found at $1 < z < 1.3$. These were culled from over 20, 000 Keck spectra collected as part of DEEP and are unique among high redshift massive galaxy samples in being kinematically selected. We intend to test whether these potentially very young galaxies are likely precursors to massive local disks, assuming no further merging. NIC-2 images provide rest-frame optical morphologies that will show whether they are normal disky systems or instead more disturbed looking objects with multiple subcomponents, mergers, peculiar structure, etc. NIC-2 provides near-IR resolutions sufficient to enable measurements of bulges and disks subcomponents. The near-IR will fill a critical gap in the broad-band SED photometry of the galaxy and its subcomponents to estimate mean stellar ages and stellar masses and to assess whether old stellar bulges and disks are in place at that time. Finally, this sample will yield the first statistically significant results on the $z > 1$ evolution of the Tully-Fisher relation for massive galaxies. In addition, we propose parallel observations with ACS WFC {V and I bands} and WFPC2 {I-band}. These will target up to 700 galaxies at redshifts 0.7 … 1.2 for which the DEEP2 survey has obtained precision redshifts and high-resolution kinematic data. The added HST morphology and color information will allow a variety of detailed studies on dynamical, structural, and photometric evolution of galaxies.
NIC2 10527
Imaging Scattered Light from Debris Disks Discovered by the Spitzer Space Telescope Around 20 Sun-like Stars
We propose to use the high contrast capability of the NICMOS coronagraph to image a sample of newly discovered circumstellar disks associated with sun-like stars. These systems were identified by their strong thermal infrared emission with the Spitzer Space Telescope as part of the Spitzer Legacy Science program titled, “The Formation and Evolution of Planetary Systems {FEPS}.” Modelling of the thermal excess emission in the form of spectral energy distributions alone cannot distinguish between narrowly confined high opacity disks and broadly distributed, low opacity disks. However, our proposed NICMOS observations can, by imaging the light scattered from this material. Even non- detections will place severe constraints on the disk geometry, ruling out models with high optical depth. Unlike previous disk imaging programs, our program contains a well defined sample of solar mass stars covering a range of ages from ~10Myrs to a few Gyrs, allowing us to study the evolution of disks from primordial to debris for the first time. These results will greatly improve our understanding of debris disks around Sun- like stars at stellar ages nearly 10x older than any previous investigation. Thus we will have fit a crucial piece into the puzzle concerning the formation and evolution of our own solar system.
ACS/HRC/WFC 10514
Kuiper Belt Binaries: Probes of Early Solar System Evolution
Binaries in the Kuiper Belt are a scientific windfall: in them we have relatively fragile test particles which can be used as tracers of the early dynamical evolution of the outer Solar System. We propose a Snapshot program using the ACS/HRC that has a potential discovery efficiency an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. By more than doubling the number of observed objects in dynamically hot and cold subpopulations we will be able to answer, with statistical significance, the question of whether these groups differ in the abundance of binaries as a result of their particular dynamical paths into the Kuiper Belt. Today’s Kuiper Belt bears the imprints of the final stages of giant-planet building and migration; binaries may offer some of the best preserved evidence of that long-ago era.
ACS/HRC 10512
Search for Binaries Among Faint Jupiter Trojan Asteroids
We propose an ambitious SNAPSHOT program to survey faint Jupiter Trojan asteroids for binary companions. We target 150 objects, with the expectation of acquiring data on about 50%. These objects span Vmag = 17.5-19.5, a range inaccessible with ground-based adaptive optics. We now have a significant sample from our survey of brighter Trojans to suggest that the binary fraction is similar to that which we find among brighter main-belt asteroids, roughly 2%. However, our observations suggest a higher binary fraction for smaller main-belt asteroids, probably the result of a different formation mechanism {evident also from the physical characteristics of the binaries}. Because the collision environment among the Trojans is similar to that of the Main Belt, while the composition is likely to be very different, sampling the binary fraction among the fainter Trojans should help us understand the collisional and binary formation mechanisms at work in various populations, including the Kuiper Belt, and help us evaluate theories for the origin of the Trojans. Calibration of and constraints on models of binary production and collisional evolution can only be done using these large-scale, real-life physical systems that we are beginning now to find and utilize.
ACS/WFC 10496
Decelerating and Dustfree: Efficient Dark Energy Studies with Supernovae and Clusters
We propose a novel HST approach to obtain a dramatically more useful “dust free” Type Ia supernovae {SNe Ia} dataset than available with the previous GOODS searches. Moreover, this approach provides a strikingly more efficient search-and-follow-up that is primarily pre- scheduled. The resulting dark energy measurements do not share the major systematic uncertainty at these redshifts, that of the extinction correction with a prior. By targeting massive galaxy clusters at z > 1 we obtain a five-times higher efficiency in detection of Type Ia supernovae in ellipticals, providing a well-understood host galaxy environment. These same deep cluster images then also yield fundamental calibrations required for future weak lensing and Sunyaev-Zel’dovich measurements of dark energy, as well as an entire program of cluster studies. The data will make possible a factor of two improvement on supernova constraints on dark energy time variation, and much larger improvement in systematic uncertainty. They will provide both a cluster dataset and a SN Ia dataset that will be a longstanding scientific resource.
ACS/HRC 10473
Rings of Uranus: Dynamics, Particle Properties and Shepherding Moons
We propose to image the rings and small inner satellites of Uranus using the High Resolution Channel of the ACS. The revolutionary capabilities of the ACS will allow us to address a variety of important questions relating to ring properties and ring-moon interactions. Observations at a range of wavelengths and phase angles will reveal the opposition surges of these rings and moons, providing information on color and surface structure. Measurements of the ring in front of the planet will provide complementary information on optical depth; any variations of optical depth with wavelength will reveal the rings’ poorly-constrained population of embedded dust. The rings of Uranus are closing rapidly as the planet approaches equinox in 2007, an event that takes place only every 42 years. Using this opportunity, our observations will be repeated at different solar and terrestrial tilt angles; this sequence of images will be particularly valuable for constraining the physical thickness and packing density of the rings. We will place particular emphasis on the rotational variations of the Epsilon Ring, whose radial width {and therefore its packing density} varies by a factor of five. In addition, deep exposures through the CLEAR filter will enable us to detect and recover 4-5 km moons in or near the ring system. Dynamicists invoke numerous such moons to “shepherd” the many sharp ring boundaries, so this will serve as a definitive test of the theory.
ACS/WFC 10430
Identifying the Major Star Formation Epoch{s} in the Outlying M31 Dwarf Spheroidal Companion
The Galaxy’s dwarf spheroidal {dSph} companions show a surprising diversity in the epochs of their major star formation episodes, which extend from ~15 to ~1 Gyr. For Galactic dSphs there is correlation between Galactocentric distance and the prominence of intermediate-age {~2-10 Gyr} populations; the dSphs with extended star formation lie at larger Galactocentric distance. This correlation may also apply to M31’s dSph companions. Our WFPC2 data {Da Costa et al. 2000} show that And II lies at a true distance of between 160 and 230 kpc from M31, comparable to the Galactocentric distances of the Galaxy’s outer dSphs satellites, and further than the other M31 Companions studied in detail so far. This dSph shows convincing evidence for an intermediate-age {~6-9 Gyr} population, which the other well-studied M31 dSphs lack. Only the recently discovered M31 dSphs companions And VI and Cassiopeia lie at larger distances from the center of M31 than And II. The pri mary aim of this proposal is to determine a color-magnitude diagram for the Cassiopeia dSph which reaches below the horizontal branch. With these data we will constrain the epoch of the main star formation episode in Cassiopeia, adding to our knowledge of how star formation in dwarf galaxies is affected by the presence of a larger neighbor. Additional results will include measurement of the true distance from M31, mean abundance, abundance dispersion, and the variable star content. With these observations, the investigation of the stellar populations down to the horizontal branch of the known M31 dSphs with HST will be complete.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
10318 -Trickle Charge Elapsed Timer OOL @168/0213z
On DOY 168/02:13:59 Mnemonic QTCELAP=9160 flagged ool. This signified the threshold 0f 8520 seconds was breached. Upon exiting a T2 slew @ 02:50:35 the mnemonic returned in bounds.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES:
- 1486-3 – Restore Values following BCT @167/1549z
- 1494-0 – Adjust ROC Error Counter @167/1551z
- 1494-1 – Adjust ROC Error Counter @167/1609z
- 1491-1 – Battery 1 BCT Limit Updates @167/1646z
SCHEDULED SUCCESSFUL
FGS GSacq 27 27
FGS REacq 17 17
OBAD with Maneuver 74 74
SIGNIFICANT EVENTS: (None)
