* Astronomy

STATUS REPORT: NASA Hubble Space Telescope Daily Report #4123
Date Released: Tuesday, May 30, 2006

OBSERVATIONS SCHEDULED

NICMOS 8791
NICMOS Post-SAA calibration - CR Persistence Part 2

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 10923
Measuring the size of the close-in transiting extrasolar planet HD 189733b
A new transiting exoplanet was found by our radial velocity search around the bright K dwarf HD 189733. With an apparent V magnitude of 7.67 and a distance of 19 pc, it is the closest star known with a transiting extrasolar planet. Moreover, the high radius ratio {Rpl/R ~ 0.17} makes it a uniquely favourable target for exoplanet studies. This planet is set to become the most observed hot Jupiter and a landmark in the understanding of hot Jupiter structure and formation. We propose a fundamental observations with the HST: to measure precisely the size of the transiting planet around HD189733 and the inclination angle of its orbit. The radius is an important characteristic of the planet in itself. A precise, model-independent radius determination is also a necessary prerequisite for further observations of the system with ground-based large telescopes and Spitzer {e.g. to detect reflected light and intrinsic infrared light from the planet, to measure the Rossiter-McLaughlin effect}. This observation requires a high-accuracy spectrophotometry light curve with ACS in the visible. Similar observations for the formerly closest transiting planet, HD 209458b, have revealed that the planet was much larger than accounted for by any model, and undergoing strong evaporation, two observations that have had a profound impact on our understanding of the structure of close-in exoplanets and the migration process.

ACS/HRC/WFPC2/NIC3 10842
A Cepheid Distance to the Coma Cluster
We propose to use the Advanced Camera for Surveys to search for Cepheid variables in two spiral galaxies in the core of the Coma cluster. A direct application of the canonical primary distance indicator at 100 Mpc will measure the far-field Hubble constant free of many of the systematic uncertainties which beset current determinations relying on secondary indicators. Establishing the far-field H_o with Cepheids will provide one of the strongest links in the extragalactic distance scale and will directly calibrate the fiducial fundamental plane of elliptical galaxies in Coma. With ACS/HRC, S/N=5 to 10 or better can be reached for Cepheids with periods of 40d to 70d at mean light in 5 orbits with the F606W filter if H_o=72 km/s/Mpc. Efficient detection and phasing can be done with twelve epochs optimally spaced for periods of 40-70d.

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.

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/HRC 10752
Cycle 14 Focus Monitor
The focus of HST is measured primarily with ACS/HRC over full CVZ orbits to obtain accurate mean focus values via a well sampled breathing curve. Coma and astigmatism are also determined from the same data in order to further understand orbital effects on image quality and optical alignments. To monitor the stability of ACS to WFPC2 relative focii, we've carried over from previous focus monitor programs parallel observations taken with the two cameras at suitable orientations of previously observed targets, and interspersed them with the HRC CVZ visits.

WFPC2 10751
WFPC2 CYCLE 14 Intflat Linearity Check and Filter Rotation Anomaly Monitor
Intflat observations will be taken to provide a linearity check: the linearity test consists of a series of intflats in F555W, in each gain and each shutter. A combination of intflats, visflats, and earthflats will be used to check the repeatability of filter wheel motions. {Intflat sequences tied to decons, visits 1-18 in prop 10363, have been moved to the cycle 14 decon proposal 10744 for easier scheduling.} Note: long-exposure WFPC2 intflats must be scheduled during ACS anneals to prevent stray light from the WFPC2 lamps from contaminating long ACS external exposures.

WFPC2 10748
WFPC2 CYCLE 14 Standard Darks
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.

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 constrain 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 centres 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.

FGS 10614
Internal Structure and Figures of Binary Asteroids
The goal of this proposal is to obtain very important information on the internal structure of a number of asteroids, and insight on the gravitational reaccumulation-process after a catastrophic disruptive collision. High resolutions observations with the HST/FGS interferometer are proposed to obtain high precision data for the topographic shape and size of a number of selected asteroids. Here we focus on objects with satellites, hence with known masses, so that the bulk density and porosity will be derived in the most accurate manner. This will yield plausible estimates on the internal properties of the objects, test wether they are close or not to figures of equilibrium {in terms of shape and adimensional rotational frequency}, and provide estimates of their relative density. The HST/FGS in interferometric mode is an ideal facility to carry out this program.

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 z1 which is heavily weighted towards the discovery of such "stalled PPNs". Supporting kinematic observations using long-slit optical spectroscopy {with the Keck}, millimetre 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 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/WFC 10515
The Unique Star Cluster System of M85
Even with its long history as one of the pillars of modern astronomy, the study of star clusters has continued to reveal new and surprising things. Over the past decade, numerous programs with HST have shown that extragalactic star clusters powerfully probe the processes of galactic formation, evolution, and destruction. The diversity of star cluster systems is a testament to the rich variation in galaxy properties. During the course of the ACS Virgo Cluster Survey, we have discovered that the early-type galaxy M85 has a system of star clusters unlike any other galaxy studied to date. Hundreds of star clusters in M85 are fainter and more extended than typical globular clusters, and have no local analogue. We propose deep optical- infrared imaging with ACS and NICMOS to obtain ages, metallicities, luminosities, and sizes of unprecedented precision to characterize these new star clusters and unravel the evolutionary state of M85 that gave rise to them.

NIC2 10510
Morphology of massive early-type galaxies at z>1.2: constraining galaxy formation models
We ask for NICMOS-NIC2 H-band imaging of a sample of 10 massive early-type galaxies spectroscopically identified at 1.2 < z < 1.7. Our aim is to look for possible relics of merging events of their formation/evolution in their morphology. The requested observations, sampling their rest- frame at lambda>6500A, would map the mass distribution of the bulk of their stellar content. The targets have been revealed by our group on the basis of near-IR spectroscopy obtained in the framework of a spectroscopic survey of a complete sample of bright EROs {Ks1. Other data are needed to infer how they have assembled such high stellar masses, i.e. to trace back their evolution. The requested observations would allow us to reveal signs of past interaction/merger event. A smooth r^{1/m} profile, coupled with no other signs of interaction/merger {disturbed morphology}, would place the possible merger event of formation 1-2 Gyr before their redshift z approx 1.5, i.e. at z > 2-3. On the other hand, if signs of recent merger events will be found, the last merger event forming the local massive spheroids will be constrained at 1.5 greater z greater 2. Thus, the requested HST observations will allow for the first time to see how massive early-type galaxies at z approx 1.5 look like, constraining in any case the redshift of the possible merging event of their formation.

ACS/HRC 10508
Orbits, Masses, and Densities of Three Transneptunian Binaries
The subset of transneptunian objects {TNOs} having natural satellites offers unique opportunities for physical studies of these distant relics from the outer parts of the protoplanetary nebula. HST/ACS is ideally suited to determining orbits of TNO satellites, resulting in the system masses. In conjunction with thermal emission observations by Spitzer, which provides sizes, we can determine the densities of TNOs. Densities offer a powerful window into their bulk compositions and interior structures.

NIC3/ACS/WFC 10504
Characterizing the Sources Responsible for Cosmic Reionisation
Our group has demonstrated the role that massive clusters, acting as powerful cosmic lenses, can play in constraining the abundance and properties of low-luminosity star-forming sources beyond z~6; such sources are thought to be responsible for ending cosmic reionisation. The large magnification possible in the critical regions of well-constrained clusters brings sources into view that lie at or beyond the limits of conventional exposures such as the UDF, as well as those in imaging surveys being undertaken with IRAC onboard Spitzer. We have shown that the combination of HST and Spitzer is particularly effective in delivering the physical properties of these distant sources, constraining their mass, age and past star formation history. Indirectly, we therefore gain a valuable glimpse to yet earlier epochs. Recognizing the result {and limitations} of the UDF exposure, we propose a systematic search through 6 lensing clusters with ACS and NICMOS for further z~6-7 sources in conjunction with existing deep IRAC data. Our survey will mitigate cosmic variance and extend the search both to lower luminosities and, by virtue of the NICMOS/IRAC combination, to higher redshift. The goal is to count and characterize representative sources at z~6-10 and to delineate the redshift range of activity for the planning of future observations.

WFPC2 10501
Extending the Heritage: Clusters, Dust, and Star Formation in M51
Strongly interacting systems in the Local Universe offer the opportunity to investigate the modality of star formation under dynamical conditions more typical of the intermediate redshift Universe {z~0.5-1}, at an exquisite resolution unmatched by distant galaxies. M51 is one such system. Most recently, the Hubble Heritage program dedicated 24 HST orbits to obtain a 3X2 ACS mosaic of M51 in BVI, and Halpha. While this is designed to produce a lovely multi-colour image of this photogenic target, its scientific return will be limited for star formation studies. Hence we propose to augment these observations by obtaining WFPC2 U band and NICMOS H band primary imaging {with NICMOS Paschen alpha in parallel} of selected pointings of this interacting galaxy system. At the modest cost of 14 additional orbits, we will: {1} accurately determine the ages of the young star cluster population; {2} secure the identification of 60-70 old globular clusters; {3} search for heavily dust enshrouded stellar clusters; {4} investigate the distribution of the cluster populations as a function of location {galactocentric, arms, interarms, etc.}; and {5} both remove the effects of dust and determine its properties. In addition to our specific science goals, these observations lend themselves, on their own or in synergy with data from GALEX and Spitzer, to a host of other investigations, including those on evolved diffuse stellar populations, galactic structure, and dust radiative transfer. We will thus release these data early to the community, by relinquishing part of the proprietary period.

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 10488
The Most Massive Galaxies in the Universe: colour-Gradients and Texture
We are proposing an HST snapshot survey of 40 objects with velocity dispersion larger than 350 km/s, selected from the Sloan Digital Sky Survey and confirmed to be single massive galaxies by the ACS-HRC i-band imaging obtained during Cycle 13. This sample of the most massive galaxies in the Universe is interesting because these objects potentially harbour the most massive black holes, and because their existence places strong constraints on galaxy formation models. These objects are unusual for another reason than their abnormally large velocity dispersions: they appear to be bluer than expected from extrapolation of the colour-velocity dispersion relation of normal early-types to these large velocity dispersions. The bluer than expected colours indicate that the formation histories of these objects are likely to be rather different than for normal early-types. This difference is also expected to manifest as abnormal colour-gradients. ACS-HRC imaging in one other band {i.e. the g-band} will allow us not simply to analyse colour gradients in these objects but also to study their colour texture and topology. This study will provide important information about the formation history of galaxies.

ACS/HRC 10474
Shooting Stars: Looking for Direct Evidence of Massive Central Black Holes in Globular Clusters
We propose to make observations that directly test the proposition that globular clusters contain massive black holes. Our targets are the bulge globular clusters NGC 6388 and NGC 6441. These are probably among the most massive in the galaxy, but are understudied compared to more familiar objects such as M15. Our analysis suggests that these two clusters are the most likely to show unambiguous evidence for a central massive black hole if such things exist in globular clusters. The observations proposed will give us the first thorough kinematic and photometric studies of these two clusters. The combination of the two epochs will give us proper motions good to of order 6 km/s. In addition, they will provide us with the first good, deep, colour-magnitude diagrams for these clusters. These diagrams will be used to investigate the make up of the stellar population in the clusters, to more firmly establish their distances, ages, and metallicities, and to search for a binary sequence. 

Source: Space Telescope Science Institute