NASA Hubble Space Telescope Daily Report #4029
HUBBLE SPACE TELESCOPE – Continuing to collect World Class Science
DAILY REPORT #4029
PERIOD COVERED: UT January 16, 2006 (DOY 016)
OBSERVATIONS SCHEDULED
ACS/HRC 10542
Charting the Sparkling Star Formation in NGC346
New, stunning V, I images of the youngest and most massive star forming region NGC 346, in the Small Magellanic Cloud, have been recently obtained with the HST/ACS. They reveal a myriad of small compact clusters: some are still embedded in dust, possibly connected by gas and dust filaments. We also discover a rich population of pre-main sequence low mass stars {~3 -0.6 Mo} mainly distributed in the body of NGC 346 and in these compact clusters, which formed with the central cluster {~5My ago}, but have not reached the main sequence yet. The immediate question that emerges is: how did star formation occur in this region? Is there evidence for an age spread among these clusters, that could be indicative of sequential star formation? We are, therefore, requesting an immediate follow up investigation with the ACS/HRC to perform a comprehensive UV/U study of the ten largest clusters identified in the NGC 346 region, with the objective of determining, in combination with the already available deep V, I data, their mass function, their upper mass cut-off, whether mass segregation is present, whether there are age variations, and what is the impact of the stellar feedback, with the final aim to establish how star formation has occured and progressed in this low metallicity environment.
ACS/HRC 10607
Probing Circumstellar and Interstellar Dust with Scattered-Light Echoes
Scattered-light echoes are one of the most powerful and efficient probes of the structure and composition of dust in circumstellar and interstellar {ISM} environments. Observations of light echoes provide exact three-dimensional positions of dust while constraining its density, grain- size and chemical make-up. Furthermore, echoes can be used as distance indicators via polarization measurements. We propose to take deep, high-resolution ACS/HRC images of five supernovae {SNe}. Two of these, SNe 1991T and 1998bu, have known circumstellar echoes that have only recently become fully resolvable with HST, and therefore require new observations. Only four echo-producing SNe are currently known, and in an attempt to increase this sample, we will also observe SNe 1999bw, 2002hh, and 2004dj. All three SNe are strong candidates for producing echoes from circumstellar and ISM dust, but only at angular sizes that HST can resolve. With these observations, we will use light echoes to their full advantage, to study {1} the mass-loss histories of Type II and Ia SN progenitors, {2} the contributions of these SNe and their progenitors to the dust content of their galaxies, {3} the structure of gas and stars in the ISM of external galaxies, and {4} we will independently measure the distance to the host galaxies, including a member of the Virgo cluster, and M96, a Type Ia cosmological distance- scale calibrator.
ACS/HRC 10627
A Snapshot Survey of Post-AGB Objects and Proto-Planetary Nebulae
We propose an ACS/HRC snapshot survey of 50 post-AGB sources, objects which have evolved from the AGB but may or may not become planetary nebulae {PNe}. This survey will complement existing HST images of proto-planetary nebulae {PPNe} and PNe in addressing circumstellar envelope morphology as a function of: 1} the progenitor star mass; 2} the chemical composition; and 3} evolutionary stage. We will connect the observed diversity of nebualar shapes with the main physical and chemical conditions characterizing post-AGB objects, to identify the mechanism that breaks the symmetry of AGB mass loss. To our knowledge, no previous HST projects have been specifically designed to address this issue. From our database of 360 post-AGB candidates, we have selected approximately 50 targets, none of which have been or are being observed with HST, to sample different central star masses, chemical compositions, and evolutionary stages, uniformly across the sky. These new data will also provide important constraints to a quantitative analysis of Spitzer Space Telescope {SST} observations planned for a similar sample of objects. We will model the HST images and SST spectra using our axisymmetric dust code 2-Dust, to derive dust density distributions, pole to equator density ratios, dust shell masses, inclination angles as well as dust composition.
ACS/HRC/WFC 10514
Kuiper Belt Binaries: Probes of Early Solar System Evolution
Binaries in the Kuiper Belt are a scientific windfall: in them we have relatively fragile test particles which can be used as tracers of the early dynamical evolution of the outer Solar System. We propose a Snapshot program using the ACS/HRC that has a potential discovery efficiency an order of magnitude higher than the HST observations that have already discovered the majority of known transneptunian binaries. By more than doubling the number of observed objects in dynamically hot and cold subpopulations we will be able to answer, with statistical significance, the question of whether these groups differ in the abundance of binaries as a result of their particular dynamical paths into the Kuiper Belt. Today’s Kuiper Belt bears the imprints of the final stages of giant-planet building and migration; binaries may offer some of the best preserved evidence of that long-ago era.
ACS/HRC/WFC 10729
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.
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/WFC 10543
Microlensing in M87 and the Virgo Cluster
Resolving the nature of dark matter is an urgent problem. The results of the MACHO survey of the Milky Way dark halo toward the LMC indicate that a significant fraction of the halo consists of stellar mass objects. The VATT/Columbia survey of M31 finds a similar lens fraction in the M31 dark halo. We propose a series of observations with ACS that will provide the most thorough search for microlensing toward M87, the central elliptical galaxy of the Virgo cluster. This program is optimized for lenses in the mass range from 0.01 to 1.0 solar masses. By comparing with archival data, we can detect lenses as massive as 100 solar masses, such as the remnants of the first stars. These observations will have at least 15 times more sensitivity to microlensing than any previous survey, e.g. using WFPC2. This is due to the factor of 2 larger area, factor of more than 4 more sensitivity in the I-band, superior pixel scale and longer baseline of observations. Based on the halo microlensing results in the Milky Way and M31, we might expect that galaxy collisions and stripping would populate the overall cluster halo with a large number of stellar mass objects. This program would determine definitively if such objects compose the cluster dark matter at the level seen in the Milky Way. A negative result would indicate that such objects do not populate the intracluster medium, and may indicate that galaxy harassment is not as vigorous as expected. We can measure the level of events due to the M87 halo: this would be the best exploration to date of such a lens population in an elliptical galaxy. Star-star lensing should also be detectable. About 20 erupting classical novae will be seen, allowing to determine the definitive nova rate for this giant elliptical galaxy. We will determine if our recent HST detection of an M87 globular cluster nova was a fluke, or indicative of a 100x higher rate of incidence of cataclysmic variables and nova eruptions in globulars than previously believed. We will examine the populations of variable stars, and will be able to cleanly separate them from microlensing.
ACS/WFC 10626
A Snapshot Survey of Brightest Cluster Galaxies and Strong Lensing to z = 0.9
We propose an ACS/WFC snapshot survey of the cores of 150 rich galaxy clusters at 0.3 < z < 0.9 from the Red Sequence Cluster Survey {RCS}. An examination of the galaxian light in the brightest cluster galaxies, coupled with a statistical analysis of the strong-lensing properties of the sample, will allow us to contrain the evolution of both the baryonic and dark mass in cluster cores, over an unprecedented redshift range and sample size. In detail, we will use the high- resolution ACS images to measure the metric {10 kpc/h} luminosity and morphological disturbances around the brightest clusters galaxies, in order to calibrate their accretion history in comparison to recent detailed simulations of structure formation in cluster cores. These images will also yield a well-defined sample of arcs formed by strong lensing by these clusters; the frequency and detailed distribution {size, multiplicity, redshifts} of these strong lens systems sets strong constraints on the total mass content {and its structure} in the centers of the clusters. These data will also be invaluable in the study of the morphological evolution and properties of cluster galaxies over a significant redshift range. These analyses will be supported by extensive ongoing optical and near-infrared imaging, and optical spectroscopy at Magellan, VLT and Gemini telescopes, as well as host of smaller facilities.
WFPC2 10744
WFPC2 Cycle 14 Decontaminations and Associated Observations
This proposal is for the WFPC2 decons. Also included are instrument monitors tied to decons: photometric stability check, focus monitor, pre- and post-decon internals {bias, intflats, kspots, & darks}, UV throughput check, VISFLAT sweep, and internal UV flat check.
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.
WFPC2 10778
WFPC2 WF4 Supplemental Darks
An 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. The severity and frequency of the problem is rapidly increasing, and it is possible that WF4 will soon become unusable if no work-around is found. The other three CCDs {PC1, WF2, and WF3} appear to be unaffected and continue to operate properly. These darks are to supplement those in program 10748 to ensure sufficient dark frames for routine calibration. As the WF4 anomaly grows worse, we are beginning to see episodes where too many darks are corrupted and are unusable.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS:
10086 – REACQ(1,2,2) failed due to search radius limit exceeded on FGS 1 @ 016/14:47:31z
REAcq(1,2,2)scheduled at 016/14:42:49 failed due to Search Radius Limit Exceeded on FGS 1 at 14:47:31. The Map at 14:50:02 showed errors of V1=3.79, V2=-145.80, V3=0.73, RSS=145.85.
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FAILURE TIMES
FGS GSacq 08 08
FGS
REacq 06 05 016/14:47:31z
(HSTAR # 10086)
OBAD with Maneuver 27 27
SIGNIFICANT EVENTS: (None)
