Status Report

NASA Hubble Space Telescope Daily Report #4238

By SpaceRef Editor
November 13, 2006
Filed under , ,
NASA Hubble Space Telescope Daily Report #4238


– Continuing to collect World Class Science

PERIOD COVERED: UT November 09,10,11,12, 2006 (DOY 313,314,315,316)


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.

ACS/WFC 10994

Infalling Groups and the Origin of Early-Type Galaxies

The creation of the cluster early-type galaxy sequence most likely occurs in groups, as mergers are possible in such environments. Recent results have shown that groups of galaxies at half of the Hubble time show a truncated red-sequence. We are surveying two small groups that will fall into a massive cluster by z=0, to determine the morphologies of the group members. The truncation of the red sequence should show up in the morphology-density relation and in an increased merger fraction.

FGS 10927

The Weight-Watcher Program for Subdwarfs

We propose to use HST/FGS1r to measure five subdwarf spectroscopic binaries to determine masses for the components. Their metallicities, [Fe/H], range from -0.5 to -2.5, and their projected minimum separations range from 9 to 24 mas. These binaries are resolvable with HST/FGS1r but not any ground-based technique. Currently, there are only two subdwarf systems having any mass measurements. The proposed work will boost the total number of subdwarf systems with masses from two to seven, and allow us to construct the first mass-luminosity relation for low- metallicity stars.

WFPC2 10915

ACS Nearby Galaxy Survey

Existing HST observations of nearby galaxies comprise a sparse and highly non-uniform archive, making comprehensive comparative studies among galaxies essentially impossible. We propose to secure HST’s lasting impact on the study of nearby galaxies by undertaking a systematic, complete, and carefully crafted imaging survey of ALL galaxies in the Local Universe outside the Local Group. The resulting images will allow unprecedented measurements of: {1} the star formation history {SFH} of a >100 Mpc^3 volume of the Universe with a time resolution of Delta[log{t}]=0.25; {2} correlations between spatially resolved SFHs and environment; {3} the structure and properties of thick disks and stellar halos; and {4} the color distributions, sizes, and specific frequencies of globular and disk clusters as a function of galaxy mass and environment. To reach these goals, we will use a combination of wide-field tiling and pointed deep imaging to obtain uniform data on all 72 galaxies within a volume-limited sample extending to ~3.5 Mpc, with an extension to the M81 group. For each galaxy, the wide-field imaging will cover out to ~1.5 times the optical radius and will reach photometric depths of at least 2 magnitudes below the tip of the red giant branch throughout the limits of the survey volume. One additional deep pointing per galaxy will reach SNR~10 for red clump stars, sufficient to recover the ancient SFH from the color-magnitude diagram. This proposal will produce photometric information for ~100 million stars {comparable to the number in the SDSS survey} and uniform multi-color images of half a square degree of sky. The resulting archive will establish the fundamental optical database for nearby galaxies, in preparation for the shift of high-resolution imaging to the near-infrared.

ACS/WFC 10905

The Dynamic State of the Dwarf Galaxy Rich Canes Venatici I Region

With accurate distances, the nearest groups of galaxies can be resolved in 3 dimensions and the radial component of the motions of galaxies due to local density perturbations can be distinquished from cosmological expansion components. Currently, with the ACS, galaxy distances within 8 Mpc can be measured effectively and efficiently by detecting the tip of the red giant branch {TRGB}. Of four principal groups at high galactic latitude in this domain, the Canes Venatici I Group {a} is the least studied, {b} is the most populated, though overwhelmingly by dwarf galaxies, and {c} is likely the least dynamically evolved. It is speculated that galaxies in low mass groups may fail to retain baryons as effectively as those in high mass groups, resulting in significantly higher mass-to-light ratios. The CVn I Group is suspected to lie in the mass regime where the speculated astrophysical processes that affect baryon retention are becoming important.

ACS/WFC 10895

Closure on the IRAS “Big Four”: A High Contrast Study of Epsilon Eridani’s Dust Belt in Scattered Light.

The ACS / HRC coronagraph has now demonstrated an unmatched capability to detect dusty debris disks around bright, nearby stars. Among the “Big Four” debris disks discovered with IRAS twenty years ago, only Epsilon Eridani {SpT=K2V, d=3.2 pc} has yet to be targeted with ACS. Beta Pictoris, Fomalhaut and Vega have been imaged with the ACS coronagraph, with the recent detection of reflected light from Fomalhaut’s dust belt {Kalas, Graham & Clampin 2005}. The direct detection of dust scattered light around Fomalhaut shows disk structure and asymmetry that can be directly linked to dynamical models of planetary perturbation. Here we propose to use the ACS HRC and WFC to detect Eps Eri’s dust belt. A new motivation to attempt this observations arises from recent 350 micron images that reveal two dust arcs ~60 AU to the southeast and northwest of the star. Contrary to previous 850 and 450 micron maps, the northwest arc is brighter than the southeast arc, and the northwest region has not been targeted by previous STIS imaging at lower contrast. The optical detection of dust features around Eps Eri would be significant because a high resolution optical image, together with Spitzer and sub-mm images, would help anchor dynamical models of Eps Eri’s planetary system, in addition to providing direct visual indications of disk-planet interactions.

NIC2 10893

Sweeping Away the Dust: Reliable Dark Energy with an Infrared Hubble Diagram

We propose building a high-z Hubble Diagram using type Ia supernovae observed in the infrared rest-frame J-band. The infrared has a number of exceptional properties. The effect of dust extinction is minimal, reducing a major systematic tha may be biasing dark energy measurements. Also, recent work indicates that type Ia supernovae are true standard candles in the infrared meaning that our Hubble diagram will be resistant to possible evolution in the Phillips relation over cosmic time. High signal-to-noise measurements of 9 type Ia events at z~0.4 will be compared with an independent optical Hubble diagram from the ESSENCE project to test for a shift in the derived dark energy equation of state due to a systematic bias. Because of the bright sky background, H-band photometry of z~0.4 supernovae is not feasible from the ground. Only the superb image quality and dark infrared sky seen by HST makes this test possible. This experiment may also lead to a better, more reliable way of mapping the expansion history of the universe with the Joint Dark Energy Mission.

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 10880

The host galaxies of QSO2s: AGN feeding and evolution at high luminosities

Now that the presence of supermassive black holes in the nuclei of galaxies is a well established fact, other questions related to the AGN phenomena still have to be answered. Problems of particular interest are how the AGN gets fed, how the black hole evolves and how the evolution of the black hole is related to the evolution of the galaxy bulge. Here we propose to address some of these issues using ACS/WFC + F775W snapshot images of 73 QSO2s with redshifts in the range 0.3< z <0.4. These observations will be combined with similar archival data of QSO1s and ground based data of Seyfert and normal galaxies. First, we will intestigate whether interactions are the most important feeding mechanism in high luminosity AGNs. This will be done in a quantitative way, comparing the asymmetry indices of QSO2 hosts with those of lower luminosity AGNs and normal galaxies. Second, we will do a detailed study of the morphology of the host galaxies of both QSO types, to determine if they are similar, or if there is an evolutionary trend from QSO2s to QSO1s. The results from this project will represent an important step in the understanding of AGN evolution, and may also introduce a substantial modification to the Unified Model.

ACS/WFC 10876

SL2S: The Strong Lensing Legacy Survey

Strong Gravitational Lensing is an invaluable tool to constrain the absolute mass distribution of structures irrespective of their light distribution. Strong Lensing has successfully been applied to single galaxies lensing quasars into multiple images, and to massive clusters lensing background sources into giant arcs. More recently, the Sloan Lens ACS Survey also found numerous examples of isolated, yet massive ellipticals lensing background galaxies into Einstein rings. We have started the Strong Lensing Legacy Survey {SL2S} looking for strong lenses in the 170 sq. degree CFHT-Legacy Survey, using dedicated automated search procedures, optimized for detection of arcs and Einstein rings. Thanks to the unsurpassed combined depth, area and image quality of the CFHT-LS, we uncovered a new population of lenses: the intermediate mass halo and sub-halo lenses. This new population effectively bridges the gap between single galaxies and massive clusters. Here, we propose to obtain SNAPSHOT ACS images of the 50 first strong lens candidates with Einstein radii 2″< Re <9" {found in the first 45 sq. degrees of CFHT-LS data released}. The ACS images will allow us to model in details the mass distribution of this new population of lensing groups under various lensing configurations. Using ACS images, we ultimately hope to provide a better understanding of the formation of structures by studying the lensing signatures of the key population of galaxy groups.

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.

ACS/HRC 10860

The largest Kuiper belt object

The past year has seen an explosion in the discoveries of Pluto-sized objects in the Kuiper belt. With the discoveries of the methane-covered 2003 UB313 and 2005 FY9, the multiple satellite system of 2003 EL61, and the Pluto-Charon analog system of Orcus and its satellite, it is finally apparent that Pluto is not a unique oddball at the edge of the solar system, but rather one of a family of similarly large objects in the Kuiper belt and beyond. HST observations over the past decade have been critical for understanding the interior, surface, and atmosphere of Pluto and Charon. We propose here a comprehensive series of observations designed to similarly expand our knowledge of these recently discovered Pluto-sized and near-Pluto-sized Kuiper belt objects. These observations will measure objects’ sizes and densities, explore the outcome of collisions in the outer solar system, and allow the first ever look at the interior structure of a Kuiper belt object. Our wide field survey that discovered all of these objects is nearly finished, so after five years of continuous searching we are finally almost complete in our tally of these near-Pluto-sized objects. This large HST request is the culmination of this half-decade search for new planetary-sized objects. As has been demonstrated repeatedly by the approximately 100 previous orbits devoted to the study of Pluto, only HST has the resolution and sensitivity for detailed study of these distant objects.

ACS/HRC 10833

Host Galaxies of Reverberation Mapped AGNs

We propose to obtain unsaturated high-resolution images of 17 reverberation-mapped active galactic nuclei in order to remove the point-like nuclear light from each image, thus yielding a “nucleus-free” image of the host galaxy. This will allow investigation of host galaxy properties: our particular interest is determination of the host-galaxy starlight contribution to the reverberation-mapping observations. This is necessary {1} for accurate determination of the relationship between the AGN nuclear continuum flux and the size of the broad Balmer-line emitting regions of AGNs, which is important in estimating black hole masses for large samples of QSOs, and {2} for accurate determination of the bolometric luminosity of the AGN proper. Through observations in Cycles 12 and 14, we have obtained or will obtain images of 18 of the 35 objects in the reverberation-mapping compilation of Peterson et al. {2004}. These observations revealed that the host-galaxy contribution, even in the higher-luminosity AGNs, is higher than expected and that all of the reverberation-mapped AGNs will have to be observed, not just the lower-luminosity sources; each source is different, and each source is important. Therefore we request time to observe the 17 remaining reverberation-mapped AGNs.

ACS/WFC 10831

A new wide-separation Einstein Cross at z=2.7

We propose ACS F555W and F814W imaging observations of a new wide-separation Einstein Cross selected from SDSS spectroscopy through a bright anomalous emission line and confirmed recently with Keck imaging and spectroscopy. The source galaxy is a moderately luminous {L~0.2L*} Lyman-alpha emitter at z=2.699, which is magnified and extended by more than a factor of twenty, making it one of the most accessible high-redshift bright Ly-a emitters on the sky. Its apparent flux is only 1.2 magnitudes fainter than MS1612-cB58, making this an ideal system for detailed study of the metallicity and initial mass function of a high-redshift star forming galaxy. The Einstein Radius is ~1.8arcsec, one of the widest known, making future spectroscopic ground-based followup optimal. This angle subtends ~5 kpc at the lens galaxy at z=0.331. The high resolution, high signal to noise imaging we propose to obtain will allow us to build accurate lensing models, including source reconstructions; combined with existing and planned Keck spectroscopy, will make possible a map of the host dark matter halo density profile to greater than one effective light radius; and will reveal lower surface brightness features associated with the bright star-forming knot lensed into the Cross. Finally, it will be an exquisite Hubble Heritage galaxy, which will be indispensable for many other applications. We are requesting a very modest proprietary period, in order to provide high-level reductions and ancillary data publically available simultaneously.

ACS/WFC 10829

Secular Evolution at the End of the Hubble Sequence

The bulgeless disk galaxies at the end of the Hubble Sequence evolve at a glacial pace relative to their more violent, earlier-type cousins. The causes of their internal, or secular evolution are important because secular evolution represents the future fate of all galaxies in our accelerating Universe and is a key ingredient to understanding galaxy evolution in lower-density environments at present. The rate of secular evolution is largely determined by the stability of the cold ISM against collapse, star formation, and the buildup of a central bulge. Key diagnostics of the ISM’s stability are the presence of compact molecular clouds and narrow dust lanes. Surprisingly, edge-on, pure disk galaxies with circular velocities below 120 km/s do not appear to contain such dust lanes. We propose to obtain ACS/WFC F606W images of a well-selected sample of extremely late-type disk galaxies to measure the characteristic scale size of the cold ISM and determine if they possess the unstable, cold ISM necessary to drive secular evolution. Our sample has been carefully constructed to include disk galaxies above and below the critical circular velocity of 120 km/s where the dust properties of edge-on disks change so remarkably. We will then use surface brightness profiles to search for nuclear star clusters and pseudobulges, which are early indicators that secular evolution is at work, as well as measure the pitch angle of the dust lanes as a function of radius to estimate the central mass concentrations.

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 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.

NIC1/NC2/NC3 10723

Cycle 14 NICMOS dark current, shading profile, and read noise monitoring program

The purpose of this proposal is to monitor the dark current, read noise, and shading profile for all three NICMOS detectors throughout the duration of Cycle 14. This proposal is a slightly modified version of proposal 10380 of cycle 13 and 9993 of cycle12 that we cut down some exposure time to make the observation fit within 24 orbits.

FGS 10611

Precise Distances to Nearby Planetary Nebulae

We propose to carry out astrometry with the FGS to obtain accurate and precise distances to four nearby planetary nebulae. In 1992, Cahn et al. noted that “The distances to Galactic planetary nebulae remain a serious, if not THE most serious, problem in the field, despite decades of study.” Twelve years later, the same statement still applies. Because the distances to planetary nebulae are so uncertain, our understanding of their masses, luminosities, scale height, birth rate, and evolutionary state is severely limited. To help remedy this problem, HST astrometry can guarantee parallaxes with half the error of any other available approach. These data, when combined with parallax measurements from the USNO, will improve distance measurements by more than a factor of two, producing more accurate distances with uncertainties that are of the order of ~6%. Lastly, most planetary nebula distance scales in the literature are statistical. They require several anchor points of known distance in order to calibrate their zero point. Our program will provide “gold standard” anchor points by the end of 2006, a decade before any anticipated results from future space astrometry missions.

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.

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 10500

Exploring the Bottom End of the White Dwarf Cooling Sequence in the Galactic Open Cluster NGC2158

The recent discovery by our group of an unexpectedly bright and still unexplained peak in the white dwarf {WD} luminosity function {LF} of the metal rich, old open cluster NGC6791 casts serious doubts on our understanding of the physical process which rules the formation and the cooling of WDs. In order to investigate whether the same problem is present in other open clusters with different ages and metallicities, we propose deep ACS/HST observations reaching the bottom end of the WD LFs, for the first time in a young and so popolous Galactic open cluster: NGC2158.

ACS/HRC 10498

Detecting the progenitors of core-collapse supernovae

Modern supernovae searches in the nearby Universe are discovering large numbers of SNe which have massive star progenitors {Types II, Ib and Ic}. The extensive HST image archives within ~20Mpc enables their indvidual bright stellar content to be resolved. As massive, evolved stars are the most luminous single objects in a galaxy, the progenitos of core-collapse SNe should be directly detectable on pre-explosion images. Two recent highlights of our ongoing HST programme are that we have detected the first red supergiant progenitor of a normal type II supernova and shown that SN1993J came from a binary system by detecting the companion star at the position of the SN. We have detected a further two progenitor stars of normal type II-P supernovae, set mass limits on a further 7 and suggest that faint type II supernovae are unlikely to come from the collapse of very massive stars which form black holes. These discoveries are providing strong constraints on theoretical models of pre-supernova evolution and the origin of the supernova types. We request time to continue this successful project and require ACS observations of future SNe which are discovered in galaxies closer than 20Mpc which have pre-explosion HST archive images available. This will allow the SNe to be precisely positioned on the pre-explosion images. We have set a final goal for this project of determining masses and types, or setting restrictive mass-limits for 30 supernovae.


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


10502 – GSACQ(2,3,3) failed to RGA hold due to STOP flag for FGS 2 Initial indication was ROOL F2SSCEA flaggin low with a value of -10.24 at 15:28:06. The other mnemonics falgged at 15:28:20 (QF2STOPF) 15:28:22 (STOP) 15:28:27 (QF2SSDIF AND Q3SSDIF) 1st ODAB: V1 -2011.25, V2 -1533.54, V3 2349.67, RSS 3452.22 2nd ODAB: V1 -4.93, V2 3.69, V3 -0.79, RSS 6.21 MAP: V1 -0.86, V2 12.73, V3 -1.78, RSS 12.89

10503 – GSAcq(2,1,1) failed to RGA Hold Control Upon acquisition of signal at 316/09:16:16, GSAcq(2,1,1) scheduled at 316/08:56:07 – 09:04:12 was observed to have failed to RGA Hold due to stop flag (QF1STOPF) on FGS-1. Pre-acquisition OBADs attitude error corrections not available. Post-acquisition OBAD/MAP had 3-axis (RSS) value of 13.08 arcseconds.

10504 – GSacq(2.3.3) failed due to scan step limit exceeded for FGS 2 At AOS (316/22:03:30) GSAcq (2,3,3), scheduled 316/21:44:02 had failed to RGA control due to Scan Step Limit Exceeded on FGS 2. OBAD MAP RSS value = 13.63 a-s.

10505 – OBAD Failed Identification At 317/01:00:50, OBAD2 using trackers FHST-1 and FHST-2 failed. One 486 ESB message 1902 (OBAD Failed Identification) was received. OBAD2 had (RSS) value of 26750.24 arcseconds.



                         SCHEDULED      SUCCESSFUL
FGS GSacq               28                     25
FGS REacq               12                     12
OBAD with Maneuver  78                     78


SpaceRef staff editor.