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Daily Rpt #4979



 
 
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Old November 25th 09, 05:57 PM posted to sci.astro.hubble
Bassford, Lynn[_2_]
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Default Daily Rpt #4979

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #4979

PERIOD COVERED: 5am November 24 - 5am November 25, 2009 (DOY 328/10:00z-329/10:00z)

OBSERVATIONS SCHEDULED

ACS/WFC3 11735

The LSD Project: Dynamics, Merging and Stellar Populations of a Sample
of Well- Studied LBGs at z~3

A large observational effort with the ground-based ESO/VLT telescopes
allowed us to obtain deep, spatially-resolved, near-IR spectra of
complete sample of 11 Lyman-Break Galaxies at z~3.1. These
observations were used to obtain, for the first time, the metallicity
and the dynamical properties of a sample of objects that, albeit
small, is representative of the total population of the LBGs. We
propose to use HST to obtain high-resolution optical and near-IR
images of this sample of LBGs in order to study the broad-band
morphology and the stellar light distribution of these galaxies. These
images, exploiting the superior spatial resolution of HST images and
the low- background : 1- will allow a precise measure of the dynamical
mass from the velocity field derived with spectroscopy; 2- will permit
a comparison of the distribution of star formation (from the line
emission) with the underlying stellar population, and, 3- will be used
to check if the complex velocity field and the multiple line-emitting
regions detected in most targets can be ascribed to on-going mergers.
This accurate study will shed light on a number of unsolved problems
still affecting the knowledge of the LBGs.

ACS/WFC3 11882

CCD Hot Pixel Annealing

All the data for this program is acquired using internal targets
(lamps) only, so all of the exposures should be taken during Earth
occultation time (but not during SAA passages). This program emulates
the ACS pre-flight ground calibration and post launch SMOV testing
(program 8948), so that results from each epoch can be directly
compared. Extended Pixel Edge Response (EPER) and First Pixel Response
(FPR) data will be obtained over a range of signal levels for the Wide
Field Channel (WFC). The High Resolution Channel (HRC) visits have
been removed since it could not be repaired during SM4.

COS/NUV 11720

Detailed Analysis of Carbon Atmosphere White Dwarfs

We propose to obtain UV spectra for the newly discovered white dwarf
stars with a carbon-dominated atmosphere. Model calculations show that
these stars emit most of their light in the UV part of the
electromagnetic spectrum and that an accurate determination of the
flux in this region is crucial for an accurate determination of the
atmospheric parameters. It will also provide a unique opportunity to
test the atomic data and broadening theory in stellar conditions never
met before. This will play a primordial role in our path to understand
the origin of these objects as well to obtain a better understanding
of the evolution of stars in general. The principal objective we hope
to achieve with these observations are 1) obtain accurate surface
gravity/mass for these stars, 2) constrain/determine the abundance of
other elements (O, He, Mg, Ne etc.), especially oxygen, 3) verify the
accuracy of the various theoretical atomic data used in the model
calculations, 4) understand the origin and evolution of carbon
atmosphere white dwarfs, in particular whether progenitor stars as
massive as 10.5 solar masses can produce white dwarfs, rather than
supernovae. We propose to observe 5 objects chosen carefully to cover
the range of observed properties among carbon atmosphere white dwarfs
(effective temperature, surface gravity, abundance of hydrogen/helium
and magnetic field).

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.

STIS/CCD 11844

CCD Dark Monitor Part 1

The purpose of this proposal is to monitor the darks for the STIS CCD.

STIS/CCD 11846

CCD Bias Monitor-Part 1

The purpose of this proposal is to 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.

WFC3/ACS/UVIS 11724

Direct Age Determination of the Local Group dE Galaxies NGC 147 and
NGC 185

The origin of dwarf elliptical (dE) galaxies remains a mystery and the
dE galaxies of the Local Group provide the best opportunity to study
this galaxy class in detail. We propose to obtain ACS photometry of
main sequence turnoff stars in the M31 dE satellites NGC 147 and NGC
185. Because these galaxies have little to no stars younger than 1
Gyr, resolving the main sequence turnoff is required to directly
quantify their star formation histories. NGC 147 and NGC 185 are the
only two dEs for which a clean measurement is feasible with the HST.
This proposal was accepted in Cycle 15, but little data were taken
before the failure of ACS. The main sequence turnoffs of NGC 147 and
NGC 185 are expected to be at an apparent magnitude of V=29; we
request F606W/F814W imaging one half magnitude fainter than this limit
(three magnitudes fainter than the deepest previous dE observations).
Quantifying the ratio of old to intermediate-age stars will allow us
to discriminate between competing models of dE formation. On-going
Keck/DEIMOS spectroscopy of several hundred red giant stars in each of
these two dE galaxies, coupled with dynamical modeling and spectral
synthesis, will complement the ACS measurement by providing
information on chemical abundance patterns, dark matter content and
internal dynamics. The proposed ACS data will be the first to directly
quantify the onset and duration of star formation episodes in dE
galaxies, and will thereby form the cornerstone in what promises to be
the most comprehensive study of this class of galaxies.

WFC3/IR 11696

Infrared Survey of Star Formation Across Cosmic Time

We propose to use the unique power of WFC3 slitless spectroscopy to
measure the evolution of cosmic star formation from the end of the
reionization epoch at z6 to the close of the galaxy-building era at
z~0.3.Pure parallel observations with the grisms have proven to be
efficient for identifying line emission from galaxies across a broad
range of redshifts. The G102 grism on WFC3 was designed to extend this
capability to search for Ly-alpha emission from the first galaxies.
Using up to 250 orbits of pure parallel WFC3 spectroscopy, we will
observe about 40 deep (4-5 orbit) fields with the combination of G102
and G141, and about 20 shallow (2-3 orbit) fields with G141 alone.

Our primary science goals at the highest redshifts a (1) Detect Lya
in ~100 galaxies with z5.6 and measure the evolution of the Lya
luminosity function, independent of of cosmic variance; 2) Determine
the connection between emission line selected and continuum-break
selected galaxies at these high redshifts, and 3) Search for the
proposed signature of neutral hydrogen absorption at re-ionization. At
intermediate redshifts we will (4) Detect more than 1000 galaxies in
Halpha at 0.5z1.8 to measure the evolution of the
extinction-corrected star formation density across the peak epoch of
star formation. This is over an order-of-magnitude improvement in the
current statistics, from the NICMOS Parallel grism survey. (5) Trace
``cosmic downsizing" from 0.5z2.2; and (6) Estimate the evolution in
reddening and metallicty in star-forming galaxies and measure the
evolution of the Seyfert population. For hundreds of spectra we will
be able to measure one or even two line pair ratios -- in particular,
the Balmer decrement and [OII]/[OIII] are sensitive to gas reddening
and metallicity. As a bonus, the G102 grism offers the possiblity of
detecting Lya emission at z=7-8.8.

To identify single-line Lya emitters, we will exploit the wide
0.8--1.9um wavelength coverage of the combined G102+G141 spectra. All
[OII] and [OIII] interlopers detected in G102 will be reliably
separated from true LAEs by the detection of at least one strong line
in the G141 spectrum, without the need for any ancillary data. We
waive all proprietary rights to our data and will make high-level data
products available through the ST/ECF.

WFC3/IR 11926

IR Zero Points

We will measure and monitor the zeropoints through the IR filters
using observations of the white dwarf standard stars, GD153, GD71 and
GD191B2B and the solar analog standard star, P330E. Data will be taken
monthly during Cycle 17. Observations of the star cluster, NGC 104,
are made twice to check color transformations. We expect an accuracy
of 2% in the wide filter zeropoints relative to the HST photometric
system, and 5% in the medium- and narrow-band filters.

WFC3/IR/S/C 11929

IR Dark Current Monitor

Analyses of ground test data showed that dark current signals are more
reliably removed from science data using darks taken with the same
exposure sequences as the science data, than with a single dark
current image scaled by desired exposure time. Therefore, dark current
images must be collected using all sample sequences that will be used
in science observations. These observations will be used to monitor
changes in the dark current of the WFC3-IR channel on a day-to-day
basis, and to build calibration dark current ramps for each of the
sample sequences to be used by Gos in Cycle 17. For each sample
sequence/array size combination, a median ramp will be created and
delivered to the calibration database system (CDBS).

WFC3/UVIS 11565

A Search for Astrometric Companions to Very Low-Mass, Population II
Stars

We propose to carry out a Snapshot search for astrometric companions
in a subsample of very low-mass, halo subdwarfs identified within 120
parsecs of the Sun. These ultra-cool M subdwarfs are local
representatives of the lowest-mass H burning objects from the Galactic
Population II. The expected 3-4 astrometric doubles that will be
discovered will be invaluable in that they will be the first systems
from which gravitational masses of metal-poor stars at the bottom of
the main sequence can be directly measured.

WFC3/UVIS 11583

The Star Formation Rate In Nearby Elliptical Galaxies

Small amounts of star formation in normal elliptical galaxies are
suggested by several results: some surprisingly young ages from
optical line-index dating; cooling X-ray gas; and mid-IR dust
emission. Previously, it was difficult to detect low levels of star
formation, but UV imaging with WFPC3 will permit us to conclusively
identify individual O/B stars in nearby normal ellipticals by their UV
colors and magnitudes. This technique is orders of magnitude more
sensitive than previous methods, allowing detections of star formation
to levels of 1E-4 Msolar/yr. Proof of concept is provided by a very
long UV ACS observation of M87 that revealed many O/B stars. We
propose observations of four normal ellipticals where recent star
formation is likely. This will yield their star formation rates and
the locations of such activity.

WFC3/UVIS 11594

A WFC3 Grism Survey for Lyman Limit Absorption at z=2

We propose to conduct a spectroscopic survey of Lyman limit absorbers
at redshifts 1.8 z 2.5, using WFC3 and the G280 grism. This
proposal intends to complete an approved Cycle 15 SNAP program
(10878), which was cut short due to the ACS failure. We have selected
64 quasars at 2.3 z 2.6 from the Sloan Digital Sky Survey
Spectroscopic Quasar Sample, for which no BAL signature is found at
the QSO redshift and no strong metal absorption lines are present at z
2.3 along the lines of sight. The survey has three main

observational goals. First, we will determine the redshift frequency
dn/dz of the LLS over the column density range 16.0 log(NHI) 20.3
cm^-2. Second, we will measure the column density frequency
distribution f(N) for the partial Lyman limit systems (PLLS) over the
column density range 16.0 log(NHI) 17.5 cm^-2. Third, we will
identify those sightlines which could provide a measurement of the
primordial D/H ratio. By carrying out this survey, we can also help
place meaningful constraints on two key quantities of cosmological
relevance. First, we will estimate the amount of metals in the LLS
using the f(N), and ground based observations of metal line
transitions. Second, by determining f(N) of the PLLS, we can constrain
the amplitude of the ionizing UV background at z~2 to a greater
precision. This survey is ideal for a snapshot observing program,
because the on-object integration times are all well below 30 minutes,
and follow-up observations from the ground require minimal telescope
time due to the QSO sample being bright.

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.

STIS/CCD/MA1/MA2 11866

Echelle Grating Blaze Function Zero Points

We will observe the flux standard G191B2B, obtaining echelle spectra
in all primary and intermediate wavelength settings. While this was
done in cycle 10 (8915), the echelle blaze shift has proved to depend
sensitively on side of operation, time and the exact MSM positioning.
We therefore believe it is important to obtain a complete set of post-
repair data at default MSM position to allow a comprehensive solution
for the echelle blaze shifts on a repaired side 2.

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#12102 GSAcq(1,2,1)@329/02:21:59z, REAcq(1,2,1) @03:30:17z;
REAcq(1,2,1) @04:02:14z & REAcq(1,2,1) @05:06:12z all failed because
FGS Sequential Attitude errors were too large to correct

Observations affected: WFC3 #74-78 Proposal #11548

#12103 GSAcq(1,2,1) @329/08:22:20z and REAcq(1,2,1) @329/09:54:10z
failed because FGS Sequential Attitude errors were too large to
correct

Observations affected: STIS #20-29, Proposal #11866

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 8 6
FGS REAcq 9 5
OBAD with Maneuver 8 8

 




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