Status Report

NASA Hubble Space Telescope Daily Report #4073

By SpaceRef Editor
March 20, 2006
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NASA Hubble Space Telescope Daily Report #4073

HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science


PERIOD COVERED: UT March 17,18,19, 2006 (DOY 076,077,078)


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/WFC 10781

Observations of the active Centaur {60558} 2000 EC98

On the next-to-last day of 2005, an amazing discovery was made. A modest member of the population of minor planets was suddenly found to be outbursting. The object, originally classified as an asteroidal body with no visible sign of coma or non-rotational photometric variations, had become a comet. {60558} 2000 EC98 is a Centaur, a class of objects that have long been seen as the precursors to many of the comets in our Solar System. This previously quiescent, fairly well-studied body has now afforded the astronomical community the opportunity to observe the changes that the earliest onset of cometary activity may bring to a planetary surface. It also allows us to test theories as to which physical characteristics may herald the potential for future activity and the existence of primordial substances, like volatiles, within the outer Solar System’s asteroidal populations. We are requesting Director’s Discretionary Time on the Hubble Space Telescope to observe this rare event with high spatial resolution, while the Centaur is still active, so that we may characterize the changes taking place on the nucleus, the robustness of the activity, and the nature of the dust and gas in the coma. Unlike the surfaces of Jupiter-Family Comets, which have been processed by long periods of activity, and unlike the few other active Centaurs, which were discovered after the onset of their activity, this would be a first and rare opportunity to study changes on a cometary surface soon after it evolved from a likely long period of dormancy into strong outburst.

ACS/WFC 10775

An ACS Survey of Galactic Globular Clusters

We propose to conduct an ACS/WFC imaging survey of Galactic globular clusters. We will construct the most extensive and deepest set of photometry and astrometry to-date for these systems reaching a main sequence mass of ~0.2 solar mass with S/N >= 10. We will combine these data with archival WFPC2 and STIS images to determine proper motions for the stars in our fields. The resultant cleaned cluster CMDs will allow us to study a variety of scientific questions. These include [but are not limited to] 1} the determination of cluster ages and distances 2} the construction of main sequence mass functions and the issue of mass segregation 3} the internal motions and dynamical evolution of globular clusters, and 4} absolute cluster motions, orbits, and the Milky Way gravitational potential. We anticipate that the unique resource provided by the proposed treasury archive will play a central role in the field of globular cluster studies for decades, with a stature comparable to that of the Hubble Deep Field for high redshift studies.

WFPC2 10772

WF4 Anomaly Characterization

A anomaly has been found in images from the WF4 CCD in WFPC2. The WF4 CCD bias level appears to have become unstable, resulting in sporadic images with either low or zero bias level. Calibration images will be obtained to further characterize the anomaly.

WFPC2 10747

WFPC2 Cycle 14 Photometric Characterization

Provide a check of the zeropoints and long-term contamination rates in WFPC2 filters. Filter/chip combinations are selected to support cycle 14 observers, as well as to provide end-of-mission data for as many combinations as possible. Extra priority is given to filters not recently observed in the Cycle 14 DECON proposal 10744, nor in the Cycle 13 photometric monitor proposal 10365. Unless otherwise constrained, preference is given to chips PC1 and WF3. For images with >2000 external images in the HST archive, we will also try to get data in WF2 and WF4 {this will provide a test of flat field accuracy, etc.}.

ACS/SBC 10743

Improved Wavelength Calibration of the SBC Prisms

Two QSOs at redshifts z=0.234 and z=0.313 will be observed in order to provide additional sampling points for the SBC prism wavelength calibration, using Ly alpha redshifted to 1500 AA and 1600 AA. Combined with the existing {Cycle 13} data, the wavelength scale will be sampled at 100 AA intervals between 1300 AA and 1700 AA.


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 Oct, 2 2005- May, 29-2006. The second half of the program has a different proposal number: 10758.

NIC2 10717

Quasar Bolometri Luminosity and Spectral Energy Distributions from Radio to X-ray

We propose to build the best SED data set spanning from radio to X-ray wavelengths for 35 quasars. We will use new and archival mid-to-far IR data from Spitzer as well as other existing multi-wavelength data. We have unique quasi-simultaneous FUV/UV-optical spectra for our sample, greatly reducing the uncertainty due to quasar intrinsic time variability in the UV bump. We will derive accurate bolometric luminosities for the sample and seek to establish a more reliable and accurate way to obtain the bolometric luminosity of quasars from their partial SEDs and/or spectral properties. We will also apply multivariate analysis to the SEDs, study the quasar multi-wavelength spectral properties and their dependence on the overall SEDs, and thus better understand the physical processes quasars employ emitting across the entire electromagnetic spectrum. HST NICMOS observations will be used to remove host galaxy contamination from the quasar SEDs. This is a joint Spitzer-HST project.

FGS 10610

Astrometric Masses of Extrasolar Planets and Brown Dwarfs

We propose observations with HST/FGS to estimate the astrometric elements {perturbation orbit semi-major axis and inclination} of extra-solar planets orbiting six stars. These companions were originally detected by radial velocity techniques. We have demonstrated that FGS astrometry of even a short segment of reflex motion, when combined with extensive radial velocity information, can yield useful inclination information {McArthur et al. 2004}, allowing us to determine companion masses. Extrasolar planet masses assist in two ongoing research frontiers. First, they provide useful boundary conditions for models of planetary formation and evolution of planetary systems. Second, knowing that a star in fact has a plantary mass companion, increases the value of that system to future extrasolar planet observation missions such as SIM PlanetQuest, TPF, and GAIA.

ACS/WFC 10605

Quantifying Star Formation and Feedback: The M81 Group Dwarf Galaxies

Studies of the impact of star formation via stellar winds and supernovae {‘feedback’} on the properties of a galaxy are of fundamental importance to understanding galaxy evolution. One crucial aspect in these studies is a precise census of the recent star formation in a galaxy. The aim of this proposal is to obtain spatially resolved star formation histories with a time resolution of roughly 30 Myr over the last 500 Myr in a carefully designed sample using the absolutely unique capabilities of the ACS. Our sample comprises 10 galaxies in the M81 group which is host to a wide diversity of dwarf star forming galaxies. They span ranges of 6 magnitudes in luminosity, 1000 in current star formation rate, and 0.5 dex in metallicity. The ACS observations will allow us to directly observe the strength and spatial relationships of all of the star formation in these galaxies in the last 500 Myr. We can then quantify the star formation and measure {1} the fraction of star formation that is triggered by feedback, {2} the fraction of star formation that occurs in clusters and associations, and {3} to what degree future star formation is governed by the feedback from previous star formation. The ACS observations will be complemented with high-quality ancillary data collected by our team for all galaxies {e.g., Spitzer, UV/optical/NIR, VLA HI}. We will calculate the energy created by star formation events and compare it to the estimated energy deposited into the local ISM. This will enable us to construct prescriptions of how star formation and feedback depend on metallicity, size, gas content, and current star formation rates in galaxies. Our resolved star formation maps will be compared with star formation rates inferred from H-alpha, UV, and IR observations – allowing an independent calibration of these techniques. Recent ACS imaging by us of one galaxy in the same group clearly demonstrates the feasibility of the proposed program. Most of the sample galaxies are located in the CVZ, making this an extremely efficient program.

NIC2 10603

Multiwavelength Imaging of Edge-on Protoplanetary Disks: Quantifying the Growth of Circumstellar Dust

Young, edge-on circumstellar disks are uniquely valuable laboratories for the study of planet formation. In these objects, the central star is occulted from direct view, significant PSF artifacts are absent, and the disk is clearly seen as a central dust lane flanked by faint disk reflected light. The detailed morphology of these nebulae and its variation with wavelength provide crucial information on the disk internal structure and the properties of its constituent dust grains. A key observable is the slope defining the wavelength dependence of the dust scattering opacity, which becomes shallower when grain growth has taken place; multiwavelength resolved disk images are the key dataset enabling such measurements. Recent analyses of three different edge-on disks have revealed a diversity in their dust properties that is indicative of different degrees of dust grain evolution having taken place in each system. This characterization of disk grain growth, when applied comparatively to a larger sample of these objects, would enable the construction of an evolutionary sequence of young disks at successive stages on the road to planet formation. In pursuit of this goal, we have identified a sample of 15 edge-on disks previously discovered by HST or groundbased telescopes, but for which high fidelity, high spatial resolution images do not yet exist in both the optical and near-infrared. We propose broad-band multicolor imaging with NICMOS of all these targets, and ACS imaging of nine of these targets In combination with existing data, the proposed images will form a complete database of high resolution optical/near-IR images for these 15 disk systems. Scattered light modeling will be used to derive the disk structure and dust properties, yielding results that will be of fundamental importance for our understanding of grain properties during protoplanetary disk evolution.

ACS/WFC 10592

An ACS Survey of a Complete Sample of Luminous Infrared Galaxies in the Local Universe

At luminosities above 10^11.4 L_sun, the space density of far-infrared selected galaxies exceeds that of optically selected galaxies. These `luminous infrared galaxies’ {LIRGs} are primarily interacting or merging disk galaxies undergoing enhanced star formation and Active Galactic Nuclei {AGN} activity, possibly triggered as the objects transform into massive S0 and elliptical merger remnants. We propose ACS/WFC imaging of a complete sample of 88 L_IR > 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised Bright Galaxy Sample {RBGS: i.e., 60 micron flux density > 5.24 Jy}. This sample is ideal not only in its completeness and sample size, but also in the proximity and brightness of the galaxies. The superb sensitivity, resolution, and field of view of ACS/WFC on HST enables a unique opportunity to study the detailed structure of galaxies that sample all stages of the merger process. Imaging will be done with the F439W and F814W filters {B and I-band} to examine as a function of both luminosity and merger state {i} the evidence at optical wavelengths of star formation and AGN activity and the manner in which instabilities {bars and bridges} in the galaxies may funnel material to these active regions, {ii} the relationship between star formation and AGN activity, and {iii} the structural properties {AGN, bulge, and disk components} and fundamental parameters {effective radius and surface brightness} of LIRGs and their similarity with putative evolutionary byproducts {elliptical, S0 and classical AGN host galaxies}. This HST survey will also bridge the wavelength gap between a Spitzer imaging survey {covering seven bands in the 3.6-160 micron range} and a GALEX UV imaging survey of these galaxies, but will resolve complexes of star clusters and multiple nuclei at resolutions well beyond the capabilities of either Spitzer or GALEX. The combined datasets will result in the most comprehensive multiwavelength study of interacting and merging galaxies to date.

ACS/WFC 10588

The Host Galaxies of Post-Starburst Quasars

We propose to use ACS to conduct a snapshot imaging survey of post-starburst quasars now being discovered in signficant numbers by the Sloan Digital Sky Survey. Post-starburst quasars are broad-lined AGN that also possess Balmer jumps and high-n Balmer absorption lines indicative of luminous stellar populations on order of 100 Myr old. These objects, representing a few percent of the z < 0.5 quasar population, may be an evolutionary stage in the transition of ultraluminous infrared galaxies into normal quasars, or a type of galaxy interaction that triggers both star formation and nuclear activity. These sources may also illustrate how black hole mass/bulge mass correlations arise. Ground-based imaging of individual poststarburst quasars has revealed merger remnants, binary systems, and single point sources. Our ACS snapshots will enable us to determine morphologies and binary structure on sub-arcsecond scales {surely present in the sample}, as well as basic host galaxy properties. We will be looking for relationships among morphology, particularly separation of double nuclei, the starburst age, the quasar black hole mass and accretion rate, that will lead to an understanding of the triggering activity and mutual evolution. This project will bring quantitative data and statistics to the previously fuzzy and anecdotal topic of the "AGN-starburst connection" and help test the idea that post-starburst quasars are an early evolutionary stage of normal quasars.

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.


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.

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 10468

Jupiter’s Upper Stratospheric Hazes Probed with Ganymede

I propose to observe a disappearance of Ganymede behind the dark limb of Jupiter with five filters of the ACS/HRC camera. Two exposures in each filter can be taken during such an event. The images will provide the spectral variation of the altitude of the apparent limb of Jupiter. The altitude of the apparent limb is dependent on the presence of hazes in Jupiter’s stratosphere. Hazes of vertical optical depths below 0.001 could be detected with these observations, providing an extremely sensitive probe of high hazes. The observations probe altitudes levels near the 1-mb pressure level, for which we have very limited data. The creation of aerosols, their growth, and their transport by winds is currently a mostly theoretical study. It would significantly benefit from constraints derived from the proposed observations. ACS/HRC is the only instrument capable of the required spatial resolution in the ultraviolet. Furthermore, a favorable geometry of Ganymede’s orbit occurs only once every six years. This proposal achieves unique results with a minimum of HST time.


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


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


10174 – GSACQ(2,1,2) Fine Lock Backup on FGS 2 @ 077/2042z

GSACQ(2,1,2) occurred at 20:37:31 while vehicle was LOS. Upon AOS at 20:42:04, vehicle was in Fine Lock on FGS 2 only. No FGS flags were set, no 486 status buffer messages were received



                         SCHEDULED      SUCCESSFUL
FGS GSacq               28                     28
FGS REacq               11                     11
OBAD with Maneuver  68                     68


ACS 926/917 STB and Suspend : Flash Update

On March 18, 2006 at 4:44 AM EST, ACS entered into SUSPEND mode. The sequence leading to the suspend event was triggered while HST was passing through the South Atlantic Anomaly (SAA) (level 4). ACS was recovered successfully from SUSPEND to Operate mode on March 18th, at 11:40 PM EST via real-time commanding. The ACS command buffer FIFO pointer corruption was cleared, which was the suspected cause of the original errors and subsequent suspend. Upon AOS at March 19 at 12:18 AM, ACS had successfully intercepted the timeline and there were no indications of any more ACS Command FIFO created errors.

SpaceRef staff editor.