Status Report

NASA Hubble Space Telescope Daily Report # 4585

By SpaceRef Editor
April 11, 2008
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NASA Hubble Space Telescope Daily Report # 4585


Continuing to collect World Class Science

PERIOD COVERED: UT April 08, 2008 (DOY 099)


WFPC2 11024


This calibration proposal is the Cycle 15 routine internal monitor for WFPC2, to be run weekly to monitor the health of the cameras. A variety of internal exposures are obtained in order to provide a monitor of the integrity of the CCD camera electronics in both bays {both gain 7 and gain 15 — to test stability of gains and bias levels}, a test for quantum efficiency in the CCDs, and a monitor for possible buildup of contaminants on the CCD windows. These also provide raw data for generating annual super-bias reference files for the calibration pipeline.

FGS 11295

Trigonometric Calibration of the Distance Scale for Classical Novae

The distance scale for classical novae is important for understanding the stellar physics of their thermonuclear runaways, their contribution to Galactic nucleosynthesis, and their use as extragalactic standard candles. Although it is known that there is a relationship between their absolute magnitudes at maximum light and their subsequent rates of decline–the well-known maximum-magnitude rate-of-decline {MMRD} relation–it is difficult to set the zero-point for the MMRD because of the very uncertain distances of Galactic novae. We propose to measure precise trigonometric parallaxes for the quiescent remnants of the four nearest classical novae. We will use the Fine Guidance Sensors, which are proven to be capable of measuring parallaxes with errors of ~0.2 mas, well below what is possible from the ground.

FGS 11298

Calibrating Cosmological Chronometers: White Dwarf Masses

We propose to use HST/FGS1R to determine White Dwarf {WD} masses. The unmatched resolving power of HST/FGS1R will be utilized to follow up four selected WD binary pairs. This high precision obtained with HST/FGS1R simply cannot be equaled by any ground based technique. This proposed effort complements that done by CoI Nelan in which a sample of WDs is being observed with HST/FGS1R. This proposal will dramatically increase the number of WDs for which dynamical mass measurements are possible, enabling a better calibration of the WD mass-radius relation, cooling curves, initial to final mass relations, and ultimately giving important clues to the star formation history of our Galaxy and the age of its disk as well as in other galaxies. {This project is part of Subasavage’s PhD thesis work at Georgia State University.}

NIC1/NIC2/NIC3 8795

NICMOS Post-SAA calibration – CR Persistence Part 6

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.

NIC2 11150

Beta Pic Polarimetry with NICMOS

Debris disk stars host transient dust grains that comprise a collisional cascade with sizes ranging from planetesimals to the sub-micron. In addition to the gravity of the host star and any planets present, these grains are subject to size-dependent non-gravitational forces, e.g., corpuscular drag and radiation pressure. When a steep spectrum of grain sizes prevails, such as the Dohnanyi distribution, scattered light images preferentially trace grains with dimensionless size parameter of order unity. Thus images in scattered starlight provide unique windows on the balance of forces acting on grains at a specific size. Therefore, in an A star system such as beta Pic, the near-IR is dominated by grains close to the blow out size and therefore NICMOS traces dust on hyperbolic orbits. Scattering is fundamentally polarization sensitive, and measurements that record intensity literally see only half the picture. If linear polarization is measured then the elements of the complex scattering matrix can be reconstructed. These matrix elements provide fundamental constraints on the size, composition and structure of the scatterers. Notably, polarimetry can be used to break the degeneracy between scattering asymmetry, g, and the radial dust gradient, which are otherwise covariant in an edge-on disk. Thus, we can use polarimetry to localize the parent bodies in the beta Pic disk. In beta Pic, dust is thought to originate mainly from the sublimation of cometary bodies near periastron. The irradiation of cometary material leads to sublimation and photodissociation of ices forming porous grains consisting of a matrix of refractory material. Such grains have a characteristic scattering signature in polarized light that can be distinguished from compact grains that arise from collisional erosion of asteroidal material.

NIC3 11120

A Paschen-Alpha Study of Massive Stars and the ISM in the Galactic Center

The Galactic center (GC) is a unique site for a detailed study of a multitude of complex astrophysical phenomena, which may be common to nuclear regions of many galaxies. Observable at resolutions unapproachable in other galaxies, the GC provides an unparalleled opportunity to improve our understanding of the interrelationships of massive stars, young stellar clusters, warm and hot ionized gases, molecular clouds, large scale magnetic fields, and black holes. We propose the first large-scale hydrogen Paschen alpha line survey of the GC using NICMOS on the Hubble Space Telescope. This survey will lead to a high resolution and high sensitivity map of the Paschen alpha line emission in addition to a map of foreground extinction, made by comparing Paschen alpha to radio emission. This survey of the inner 75 pc of the Galaxy will provide an unprecedented and complete search for sites of massive star formation. In particular, we will be able to (1) uncover the distribution of young massive stars in this region, (2) locate the surfaces of adjacent molecular clouds, (3) determine important physical parameters of the ionized gas, (4) identify compact and ultra-compact HII regions throughout the GC. When combined with existing Chandra and Spitzer surveys as well as a wealth of other multi-wavelength observations, the results will allow us to address such questions as where and how massive stars form, how stellar clusters are disrupted, how massive stars shape and heat the surrounding medium, and how various phases of this medium are interspersed.

WFPC2 11017

Hubble Heritage Observations of SN1006

The Hubble Heritage team will obtain broadband images of SN1006 to combine with the Halpha data obtained in proposal 10577 (PI: Raymond). Three broadband filters will be used with two pointings of the WFPC2 to obtain star colors. A composite image of the Heritage stars along with the Halpha filament will be created, resulting in a public release image.

WFPC2 11040

Geometric Distortion / Astrometry Closeout

These observations will serve as a final characterization of the geometric distortion and astrometric calibration. The Omega-Cen inner calibration field is used. Filters F300W, F555W, and F814W are observed at 5 roll angles spanning 180 degrees; F218W is observed at a single roll angle.

WFPC2 11070

WFPC2 CYCLE 15 Standard Darks – part II

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 11113

Binaries in the Kuiper Belt: Probes of Solar System Formation and Evolution

The discovery of binaries in the Kuiper Belt and related small body populations is powering a revolutionary step forward in the study of this remote region. Three quarters of the known binaries in the Kuiper Belt have been discovered with HST, most by our snapshot surveys. The statistics derived from this work are beginning to yield surprising and unexpected results. We have found a strong concentration of binaries among low-inclination Classicals, a possible size cutoff to binaries among the Centaurs, an apparent preference for nearly equal mass binaries, and a strong increase in the number of binaries at small separations. We propose to continue this successful program in Cycle 16; we expect to discover at least 13 new binary systems, targeted to subgroups where these discoveries can have the greatest impact.


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




                        SCHEDULED      SUCCESSFUL

FGS GSacq               13                   13
FGS REacq               03                   03
OBAD with Maneuver      32                   31


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