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Daily Report #5061



 
 
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Old March 26th 10, 05:49 PM posted to sci.astro.hubble
Cooper, Joe
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Default Daily Report #5061

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5061

PERIOD COVERED: 5am March 25 - 5am March 26, 2010 (DOY 084/09:00z-085/09:00z)

OBSERVATIONS SCHEDULED

ACS/WFC 11679

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

Combined high-resolution images from Hubble and Chandra (CXO) have
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 3379 and NGC 4278 are be the first
prototypical elliptical galaxies with complete, deep CXO observations
enabling the study of LMXBs at lower luminosities. We propose
completing 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. This is
a resubmission of an approved Cycle 15 program (10835) which was only
partially completed.

ACS/WFC 11715

The Luminous Galactic Cepheid RS Puppis: A Geometric Distance from its
Nested Light Echoes

RS Puppis is one of the most luminous Cepheids in the Milky Way (P =
41.4 days) and an analog of the bright Cepheids used to measure
extragalactic distances. An accurate distance would help anchor the
zero-point of the bright end of the period-luminosity relation, but at
a distance of about 2 kpc it is too far away for a trigonometric
parallax with existing instrumentation.

RS Pup is unique in being surrounded by a reflection nebula, whose
brightness varies as pulses of light from the Cepheid propagate
outwards. Members of our team have used ground-based imaging of the
nebula to derive phase lags in the light variations of individual
features in the nebula, and have inferred a seemingly very precise
geometric distance to the star. However, there is an unavoidable
ambiguity involving the cycle counts, which was resolved by assuming
that the features lie in the plane of the sky. If this assumption is
incorrect, a large systematic error would be introduced into the
distance measurement.

We show that polarimetric imaging using the high spatial resolution of
ACS/WFC and its ability to image close to the star can resolve this
ambiguity and yield a reliable geometric distance to RS Pup. We will
also obtain a wide-field multicolor image of the nebula, in order to
study its morphology and the mass-loss history of the Cepheid.

COS/FUV 12011

Magnetic Heating of the Outer Atmospheres of Very Low Mass Dwarfs

The detections of FUV and X-ray emissions from very low mass stars and
brown dwarfs have confirmed that stellar magnetic activity can survive
even at these low stellar masses. The emissions are qualitatively
similar to those from active stars, despite the dramatic differences
between the characteristics of an ultracool (M7) stellar atmosphere
and those of earlier type cool stars. It is currently an open question
how the structures and magnetic heating which exists in these very low
mass stars compare with those seen in higher mass active stars. We
propose to take Chandra and HST/COS spectra of two nearby active very
low mass stars in order to determine the effect that these large-scale
fields have on transition region and coronal structures.

NIC2/WFC3/IR 11548

Infrared Imaging of Protostars in the Orion A Cloud: The Role of
Environment in Star Formation

We propose NICMOS and WFC3/IR observations of a sample of 252
protostars identified in the Orion A cloud with the Spitzer Space
Telescope. These observations will image the scattered light escaping
the protostellar envelopes, providing information on the shapes of
outflow cavities, the inclinations of the protostars, and the overall
morphologies of the envelopes. In addition, we ask for Spitzer time to
obtain 55-95 micron spectra of 75 of the protostars. Combining these
new data with existing 3.6 to 70 micron photometry and forthcoming
5-40 micron spectra measured with the Spitzer Space Telescope, we will
determine the physical properties of the protostars such as envelope
density, luminosity, infall rate, and outflow cavity opening angle. By
examining how these properties vary with stellar density (i.e.
clusters vs. groups vs. isolation) and the properties of the
surrounding molecular cloud; we can directly measure how the
surrounding environment influences protostellar evolution, and
consequently, the formation of stars and planetary systems.
Ultimately, this data will guide the development of a theory of
protostellar evolution.

S/C 11550

COS-GTO: X-Ray Binaries

This is a program to obtain UV spectra of soft X-ray transients (SXTs)
in their quiescent states. The target, A0620-00, is an interacting
binary system with a K7V donor star and a 9.7 M_solar black hole
accretor. Our observations will use the COS G140L and STIS G230L modes
to obtain low spectral resolution (R= 1000-2000), broadband (1230-3200
A) spectra of A0620-00. We will also obtain contemporaneous optical
spectra of the system, which varies on time scales of days. The data
will be used to establish the broadband SED of the system and to
measure emission line strengths and widths in the UV. The dereddened
SED will be modeled to determine the structure and temperature of the
accretion disk. The FUV region of the spectrum, which has not been
observed before, will be a key parameter in constraining the
temperature and inner truncation radius of the disk, which is believed
to transition to an advection-dominated accretion flow (ADAF) at large
distances from the black hole in quiescent SXTs. The UV line spectrum,
and in particular the NV 1240 and CIV 1550 transitions, will show
whether C depletions, which have been seen in the NIR spectrum of the
donor star, are present in the accretion disk and whether enhanced N
abundances are also seen, indicative of CNO processing of material
during the evolutionary history of the binary. Comparison of emission
line velocities between the optical HI emission and the ionized UV
metal transitions will also be used to constrain the relative extents
of the photoionized disk chromosphere and the bulk of the disk in
quiescent black hole binaries.

STIS/CC 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

STIS/CC 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,
and 1x1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

STIS/CCD 11849

STIS CCD Hot Pixel Annealing

This purpose of this activity is to repair radiation induced hot pixel
damage to the STIS CCD by warming the CCD to the ambient instrument
temperature and annealing radiation-damaged pixels.

Radiation damage creates hot pixels in the STIS CCD Detector. Many of
these hot pixels can be repaired by warming the CCD from its normal
operating temperature near -83 deg. C to the ambient instrument
temperature (~ +5 deg. C) for several hours. The number of hot pixels
repaired is a function of annealing temperature. The effectiveness of
the CCD hot pixel annealing process is assessed by measuring the dark
current behavior before and after annealing and by searching for any
window contamination effects.

WFC3/UV/IR 11709

Stretching the Diversity of Cosmic Explosions: The Supernovae of
Gamma-ray Bursts

While the association between gamma-ray bursts (GRBs) and massive
stars is robust, there is a large diversity of properties among
supernovae (SNe) associated with GRBs. The converse is also true:
Several recent events show that there is a large brightness range
among high energy transients associated with SNe. As part of a
comprehensive program, we propose to use HST in order to search for
and characterize the SNe associated with GRB.

HST offers the means to cleanly separate the light curve of the GRB
afterglow from the supernova, and to remove the contamination from the
host galaxy, opening a clear path to the fundamental parameters of the
SN, and thence to the progenitor. From these observations, we will
determine the absolute magnitude at maximum, the shape of the spectral
energy distribution, and any change over time of the energy
distribution. We will also measure the rate of decay of the
exponential tail.

Merged with the ground-based data that we will obtain for each event,
we will be able to compare our data set to models and constrain the
energy of the explosion, the mass of the ejecta and the mass of Nickel
synthesized during the explosion. These results will shed light on the
apparent variety of supernovae associated with gamma-ray bursts and
X-ray flashes, and on the relation between these SNe and other, more
common, types of core-collapse explosions.

WFC3/UVIS 11905

WFC3 UVIS CCD Daily Monitor

The behavior of the WFC3 UVIS CCD will be monitored daily with a set
of full-frame, four-amp bias and dark frames. A smaller set of 2Kx4K
subarray biases are acquired at less frequent intervals throughout the
cycle to support subarray science observations. The internals from
this proposal, along with those from the anneal procedure (Proposal
11909), will be used to generate the necessary superbias and superdark
reference files for the calibration pipeline (CDBS).

WFC3/UVIS 11908

Cycle 17: UVIS Bowtie Monitor

Ground testing revealed an intermittent hysteresis type effect in the
UVIS detector (both CCDs) at the level of ~1%, lasting hours to days.
Initially found via an unexpected bowtie-shaped feature in flatfield
ratios, subsequent lab tests on similar e2v devices have since shown
that it is also present as simply an overall offset across the entire
CCD, i.e., a QE offset without any discernable pattern. These lab
tests have further revealed that overexposing the detector to count
levels several times full well fills the traps and effectively
neutralizes the bowtie. Each visit in this proposal acquires a set of
three 3x3 binned internal flatfields: the first unsaturated image will
be used to detect any bowtie, the second, highly exposed image will
neutralize the bowtie if it is present, and the final image will allow
for verification that the bowtie is gone.

WFC3/UVIS 11924

WFC3/UVIS External and Internal CTE Monitor

CCD detector Charge Transfer Inefficiency (CTI)-induced losses in
photometry and astrometry will be measured using observations of the
rich open cluster NGC6791 and with the EPER (Extended Pixel Edge
Response) method using tungsten lamp flat field exposures. Although we
do not expect to see CTE effects at the outset of Cycle 17, this CTE
monitoring program is the first of a multi-cycle program to monitor
and establish CTE-induced losses with time. We expect to measure CTE
effects with a precision comparable to the ACS measurements.

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 3 3
OBAD with Maneuver 9 9

SIGNIFICANT EVENTS: (None)


 




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