HUBBLE SPACE TELESCOPE - Continuing to collect World Class Science

DAILY REPORT       # 4585

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

OBSERVATIONS SCHEDULED

WFPC2 11024

WFPC2 CYCLE 15 INTERNAL MONITOR

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 i

mages. 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.

FLIGHT OPERATIONS SUMMARY:

Significant Spacecraft Anomalies: (The following are preliminary reports

of potential non-nominal performance that will be investigated.)

HSTARS: None

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

                       SCHEDULED      SUCCESSFUL  

FGS GSacq               13                   13                  

FGS REacq               03                   03                  

OBAD with Maneuver 32                   31       

SIGNIFICANT EVENTS: (None)