Status Report

NASA Hubble Space Telescope Daily Report #4266

By SpaceRef Editor
December 26, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4266


– Continuing to collect World Class Science

PERIOD COVERED: UT December 22,23,24,25, 2006 (DOY 356,357,358,359)


NIC1/NIC2/NIC3 8794

NICMOS Post-SAA calibration – CR Persistence Part 5

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.

NIC3 11062

NICMOS non-linearity tests

This program incorporates a number of tests to analyse the count rate dependent non-linearity seen in NICMOS spectro-photometric observations. We will observe a field with stars of a range in luminosity in NGC3603 with NICMOS in NIC1: F090M, F110W, F140W, F160W NIC2: F110W, F160W, F187W, F205W, and F222M NIC3: F110W, F150W, F160W, F175W, and F222M. We will repeat the observations with flatfield lamp on, creating artificially high count-rates, allowing tests of NICMOS linearity as function of count rate. We first take exposures with the lamp off, then exposures with the lamp on, and repeat at the end with lamp off. Finally, we continue with taking darks during occultation. We will furthermore observe spectro-photometric standard P041C using the G096, G141, and G206 grisms in NIC3, and repeat the lamp off/on/off test to artificially create a high background.

ACS/HRC 11053

Earth Flats

Sky flats will be obtained by observing the bright Earth with the HRC and WFC. These observations will be used to verify the accuracy of the latest pipeline flats and to monitor any changes. Weekly coronagraphic monitoring is required to assess the changing position of the spots.

ACS/HRC 11041

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. For cycle 15 the program will cover 18 months 12.1.06->05.31.08 and it has been divied into three different proposal each covering six months. The three proposals are 11041-11042-11043.

ACS/HRC 10991

Light Echoes from SN 2006X in M100

We propose a minimal investment of spacecraft time to discover and confirm a light echo from Supernova 2006X in M100, the closest Type Ia in many years. Our spectroscopic and photometric data indicate that this SN sits behind a large amount of interstellar dust likely to produce a strong echo signal. This is one of very few cases where we will be able to study the three-dimensional environment of a SN Ia in full detail, and begin to understand how environmental effects play into the evolutionary and observational factors which influence the utility of SN Ia as standard candles for probing cosmology. We propose an efficient program to definitively detect {or not} a light echo of reasonable signal strength, to confirm that it is an echo by demonstrating apparent superluminal motion if it exists, to map the three-dimensional geometry of the reflecting interstellar structures, and to detail the reflectance properties of the dust which can be used to constrain ! its grain size and composition distribution.

ACS/WFC 10918

Reducing Systematic Errors on the Hubble Constant: Metallicity Calibration of the Cepheid PL Relation

Reducing the systematic errors on the Hubble constant is still of significance and of immediate importance to modern cosmology. One of the largest remaining uncertainties in the Cepheid- based distance scale {which itself is at the foundation of the HST Key Project determination of H_o} which can now be addressed directly by HST, is the effect of metallicity on the Cepheid Period-Luminosity relation. Three chemically distinct regions in M101 will be used to directly measure and thereby calibrate the change in zero point of the Cepheid PL relation over a range of metallicities that run from SMC-like, through Solar, to metallicities as high as the most metal- enriched galaxies in the pure Hubble flow. ACS for the first time offers the opportunity to make a precise calibration of this effect which currently accounts for at least a third of the total systematic uncertainty on Ho. The calibration will be made in the V and I bandpasses so as to be immediately and directly applicable to the entire HST Cepheid-based distance scale sample, and most especially to the highest-metallicity galaxies that were hosts to the Type Ia supernovae, which were then used to extend the the distance scale calibration out to cosmologically significant distances.


An Efficient ACS Coronagraphic Survey for Debris Disks around Nearby Stars

We propose to finish our Cycle 11 optical survey for nearby debris disks using the ACS/HRC coronagraph. Out of 43 orbits originally proposed for the survey, 23 orbits were allocated, leading to a survey of 22 stars, from which two new debris disks were imaged for the first time. Our analysis of the initial survey gives an empirical estimate for the detection rate of debris disks relative to heliocentric distance and dust optical depth. Our target list for Cycle 15 is now optimized to yield more frequent disk detections. Likewise our observing strategy is improved to maximize sensitivity per telescope orbit allocated. Therefore we present the most efficient survey possible. The scientific motivation is to obtain scattered light images of previously unresolved debris disks to determine their viewing geometry and physical architecture, both of which may characterize the underlying planetary system. We choose 25 debris disk targets for which we predict a detection rate of 25% ? 5%. Four targets have extrasolar planets from which the viewing geometry revealed by a disk detection will resolve the v sin{i} ambiguity in the planet masses. These targets present the remarkable opportunity of finally seeing a debris disk in system with known planets.

NIC3 10894

Probing the Birth of Super Star Clusters with NICMOS

The formation of “super star clusters” represents an extreme mode of star formation in the local universe. Star clusters with radii < 5pc and masses exceeding 10^4 solar masses are now known to be common in starbursts. These clusters are amazingly densely packed with massive stars, and can have a violent impact on their host galaxies and the surrounding IGM. The effects of massive star clusters perhaps were even more important in the earlier universe, when galaxy mergers and starbursts were common, and the formation of massive globular clusters was ubiquitous. However, our knowledge of the formation and early evolution of such massive clusters remains poorly understood, and observations have only begun to probe these stages. The near-IR fluxes and colors of natal clusters change dramatically in their early stages of evolution, providing important diagnostics. We will use NICMOS to explore the early evolution of massive star clusters through observations of a sample of nearby starburst galaxies containing the recently discovered ultra-young massive star clusters. First identified as compact optically- thick free-free radio sources, these natal clusters are still embedded in their birth material and obscured at optical wavelengths. Sensitive, high-resolution observations in the near-IR are critical for investigating the properties of these clusters as they evolve from being completely obscured by their natal clouds to fully emerged and optically visible. NICMOS F160W, F205W, F187N, and F190N {roughly H, K, and Pa-alpha} images will allow us to determine their ages, extinctions, ionizing fluxes, embedded stellar masses, and the morphological relationship between radio, mid-IR, and optically visible clusters. These results will ultimately provide insight into the earliest stages of super star cluster evolution and the properties of massive star formation throughout the universe.


Morphologies of the Most Extreme High-Redshift Mid-IR-Luminous Galaxies

The formative phase 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, restricting us to the study of 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 bright at mid-IR wavelengths {F[24um]>0.8mJy}, but deep ground based imaging suggests extremely faint {and in some cases extended} optical counterparts {R~24-27}. Deep K-band images show barely resolved galaxies. Mid-infrared spectroscopy with Spitzer/IRS reveals that they have redshifts z ~ 2-2.5, suggesting bolometric luminosities ~10^{13-14}Lsun! We propose to obtain deep ACS F814W and NIC2 F160W images of these sources and their environs in order to determine kpc-scale morphologies and surface photometry for these galaxies. The proposed observations will help us determine whether these extreme objects are merging systems, massive obscured starbursts {with obscuration on kpc scales!} or very reddened {locally obscured} AGN hosted by intrinsically low-luminosity galaxies.

ACS/WFC 10886

The Sloan Lens ACS Survey: Towards 100 New Strong Lenses

As a continuation of the highly successful Sloan Lens ACS {SLACS} Survey for new strong gravitational lenses, we propose one orbit of ACS-WFC F814W imaging for each of 50 high- probability strong galaxy-galaxy lens candidates. These observations will confirm new lens systems and permit immediate and accurate photometry, shape measurement, and mass modeling of the lens galaxies. The lenses delivered by the SLACS Survey all show extended source structure, furnishing more constraints on the projected lens potential than lensed-quasar image positions. In addition, SLACS lenses have lens galaxies that are much brighter than their lensed sources, facilitating detailed photometric and dynamical observation of the former. When confirmed lenses from this proposal are combined with lenses discovered by SLACS in Cycles 13 and 14, we expect the final SLACS lens sample to number 80–100: an approximate doubling of the number of known galaxy-scale strong gravitational lenses and an order-of-magnitude increase in the number of optical Einstein rings. By virtue of its homogeneous selection and sheer size, the SLACS sample will allow an unprecedented exploration of the mass structure of the early-type galaxy population as a function of all other observable quantities. This new sample will be a valuable resource to the astronomical community by enabling qualitatively new strong lensing science, and as such we will waive all but a short {3-month} proprietary period on the observations.

ACS/WFC 10882

Emission Line 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. We discovered new optical jets, dust lanes, and revealed point-like nuclei whose properties support AGN unified schemes. Here, we propose to obtain ACS emission line images at low and high excitation of 3CR sources with z<0.3, both low- and classical high- power radio galaxies, as a major enhancement to an already superb dataset. We aim to probe fundamental relationships between warm optical line-emitting gas, radio source structure {jets and lobes} and X-ray coronal halos. We will combine our existing UV images with new emission- line images to establish quantitative star formation characteristics and their relation to dust and merging, and with emission-line excitation maps, test theories on ionization beam patterns and luminosities from active nuclei. We will seek jet induced star formation and knowing optical emission-line physics, investigate quantitative jet physics. The nuclear emission line properties of the galaxies will themselves be established and used as ingredients in continuing tests of unified AGN theories. The resulting database will be an incredibly valuable resource to the astronomical community for years to come.

ACS/WFC 10875

A Snapshot Survey of The Most Massive Clusters of Galaxies

We propose the continuation of our highly successful Cycle14 snapshot survey of a sample of 123 very X-ray luminous clusters in the redshift range 0.3-0.7. As demonstrated by the 21 snapshots obtained so far in Cycle14 these systems frequently exhibit strong gravitational lensing as well as spectacular examples of violent galaxy evolution. The proposed observations will provide important constraints on the cluster mass distributions, the physical nature of galaxy-galaxy and galaxy-gas interactions in cluster cores, and a set of optically bright, lensed galaxies for further 8-10m spectroscopy. Acknowledging the broad community interest in this sample we waive our data rights for these observations.


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 10835

Probing The Globular Cluster / Low Mass X-ray Binary Connection in Early-type Galaxies At Low X-ray

Combined high-resolution imaging from Hubble and Chandra {CXO} has revolutionized our understanding of extragalactic low-mass X-ray binaries {LMXBs} and globular clusters {GCs}, yet their connection in early-type galaxies has remained unstudied at the luminosities of the Galactic LMXBs in GCs. NGC 4278 and 3379 will be the first two prototypical elliptical galaxies with deep CXO observations enabling the study of LMXBs at lower luminosities. We propose mosaic ACS observations of both galaxies {5 fields per galaxy} that will provide the most comprehensive view into the connection between GCs and LMXBs in early-type galaxies. We will detect ~860 and ~270 GCs in all of NGC 4278 and NGC 3379, respectively. These two galaxies will have among the greatest number of detected GC-LMXBs to date {~130 & 50} and will include the faintest GC-LMXBs in a normal early-type galaxy. We will measure the fraction of GCs which contain LMXBs, as a function of X-ray luminosity, galactocentric distance, color, and GC half-light radius. Using the radial profiles of optical light, GCs, and LMXBs, we will determine the percentage of field LMXBs which may have originated in GCs. We will use the measured GC properties over the entire extent of both galaxies to constrain theories of GC formation and evolution.

ACS/WFC 10809

The nature of “dry” mergers in the nearby Universe

Recent studies have shown that “dry” mergers of red, bulge-dominated galaxies at low redshift play an important role in shaping today’s most massive ellipticals. These mergers have been identified in extremely deep ground-based images of red sequence galaxies at z ~ 0.1. The ground-based images reach surface brightness limits of AB ~ 29, but lack the resolution to study the morphologies of the galaxies inside the effective radius. Here we propose to obtain ACS images of a representative sample of 40 of these red sequence galaxies: 15 ongoing dry mergers, 15 remnants, and 10 undisturbed objects. We will measure the isophote shapes and ellipticities of the galaxies, their dust content, morphological fine structure {shells and ripples}, AGN content, and their location on the Fundamental Plane. By comparing galaxies in different stages of the merging process we can constrain the amount of gas associated with these red mergers, the effect of active nuclei, and track structural changes. As two galaxies can be observed in a single orbit 20 orbits are requested to observe the 40 galaxies.

NIC2, ACS/WFC 10802

SHOES-Supernovae, HO, for the Equation of State of Dark energy

The present uncertainty in the value of the Hubble constant {resulting in an uncertainty in Omega_M} and the paucity of Type Ia supernovae at redshifts exceeding 1 are now the leading obstacles to determining the nature of dark energy. We propose a single, integrated set of observations for Cycle 15 that will provide a 40% improvement in constraints on dark energy. This program will observe known Cepheids in six reliable hosts of Type Ia supernovae with NICMOS, reducing the uncertainty in H_0 by a factor of two because of the smaller dispersion along the instability strip, the diminished extinction, and the weaker metallicity dependence in the infrared. In parallel with ACS, at the same time the NICMOS observations are underway, we will discover and follow a sample of Type Ia supernovae at z > 1. Together, these measurements, along with prior constraints from WMAP, will provide a great improvement in HST’s ability to distinguish between a static, cosmological constant and dynamical dark energy. The Hubble Space Telescope is the only instrument in the world that can make these IR measurements of Cepheids beyond the Local Group, and it is the only telescope in the world that can be used to find and follow supernovae at z > 1. Our program exploits both of these unique capabilities of HST to learn more about one of the greatest mysteries in science.

ACS/HRC 10800

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 to continue a Snapshot program using the ACS/HRC that has a demonstrated discovery potential an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. With this continuation we seek to reach the original goals of this project: to accumulate a sufficiently large sample in each of the distinct populations collected in the Kuiper Belt to be able to measure, with statistical significance, how the fraction of binaries varies as a function 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/WFC 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.

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/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/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.


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


10569 GSacq(2,3,2) failed to RGA control @ 356/1309z GSacq(2,3,2) scheduled at 356/15:05:46 failed at 13:09:36 due to scan step limit exceeded on FGS 2. OBAD1 showed errors of V1=-730.81, V2=4478.69, V3=489.56 and RSS =4564.26. OBAD2 showed errors of V1=-1.20, V2=7.22, V3=-4.65 and RSS= 8.68.

10570 REacq(2,1,1) failed to RGA control @ 356/1758z REacq(2,1,1) scheduled at 356/17:54:55 failed at 117:58:02 due to scan step limit exceeded on FGS 2. OBAD2 showed errors of V1=-0.89, V2=0.33, V3=0.02 and RSS =0.95.

10571 GSAcq(1,3,1) failed to RGA Hold (Gyro Control) @ 356/2235z The GSAcq(1,3,1)scheduled at 356/22:31:28 – 22:39:33 failed to RGA Hold due to (QF3SRLEX) Search Radius Limit Exceeded on FGS-3. Pre-acquisition OBADs showed (RSS) attitude correction values of 1837.82 and 6.39 arcseconds. Post-acquisition OBAD/MAP had 3-axis (RSS) error value of 5.61 arcseconds.

10572 REAcq (2,1,1) failed to RGA control @ 356/1946z REAcq (2,1,1) scheduled from 356/19:30:54-19:38:05 failed to RGA control due to Search Radius Limit Exceeded on FGS 2. Mnemonic QF2SRLEX was observed. OBAD #1 RSS: 823.77; OBAD #2 RSS: 5.22; OBAD MAP: Not scheduled. REAcq (2,1,1) scheduled from 356/21:06:53-21:14:04 failed to RGA control due to Search Radius Limit Exceeded on FGS 2. Mnemonic QF2SRLEX was observed. OBAD data unavailable due to LOS.

10573 GSacq (1,2,2) failed due to stop flag on FGS1 (RGA Hold) @357/1557z Upon acquisition at 16:18:17 stop flags were set for FGS1. Preacquisition OBADs RSS were 564.65 and 6.64 arcseonds. Post acquisition Map RSS = 3.89 arc seconds.

10574 GSAcq (1,3,1) failed due to Search Radius Limit Exceeded on FGS 1 @ 358/0652z At AOS 358/06:52:01 GSAcq (1,3,1) scheduled from 358/05:27:13-05:34:16 had failed due to Search Radius Limit Exceeded on FGS 1. OBAD #1: unavailable due to LOS. OBAD #2: V1 -6.52, V2 28.27, V3 22.03, RSS 36.44. OBAD Map: Not scheduled

10575 GSAcq (2,1,2) failed to RGA control @ 358/1022z At AOS 358/10:22:17, GSAcq (2,1,2) had failed to RGA control. No 486 ESB’s noted. Due to LOS, OBAD data will not be available till the next scheduled engineering data dump. OBAD Map: V1 -0.57, V2 -1074.41, V3 1.44, RSS 1074.41.

10576 CSTRUCCP Limit Violation @ 359/1405z At 359/14:05:10 and 359/14:07:27 mnemonic Structure Current Primary (CSTRUCCP) went out of limit with a value of 5.6 amps, one sample during each occurrence. The yellow high limit is 5.4 amps. The on-call SE was notified.



                                       SCHEDULED      SUCCESSFUL
GSacq                         35                        30
FGS REacq                         18                        17
OBAD with Maneuver     96                      96


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