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Daily Report #5141



 
 
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Old July 20th 10, 04:46 PM posted to sci.astro.hubble
Bassford, Lynn
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Posts: 44
Default Daily Report #5141


HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5141

PERIOD COVERED: 5am July 19 - 5am July 20, 2010 (DOY 200/09:00z-201/09:00z)

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

#12333 OBAD at 200/17:21:57z failed and GSAcq(1,2,1) at 200/17:26:57z
failed with search radius limit exceeded on FGS2

Observations affected: Astrometry Proposal #12316

From DOY 187:

#12334 ReAcq(1,0,1) at 187/04:37:32z required two attempts for FL-DV
with scan step limit exceeded on FGS1

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 9 8
FGS REAcq 7 7
OBAD with Maneuver 6 5

SIGNIFICANT EVENTS: (None)



OBSERVATIONS SCHEDULED:

ACS/WFC 11996

CCD Daily Monitor (Part 3)

This program comprises basic tests for measuring the read noise and
dark current of the ACS WFC and for tracking the growth of hot pixels.
The recorded frames are used to create bias and dark reference images
for science data reduction and calibration. This program will be
executed four days per week (Mon, Wed, Fri, Sun) for the duration of
Cycle 17. To facilitate scheduling, this program is split into three
proposals. This proposal covers 308 orbits (19.25 weeks) from 21 June
2010 to 1 November 2010.

COS/FUV 11895

FUV Detector Dark Monitor

Monitor the FUV detector dark rate by taking long science exposures
without illuminating the detector. The detector dark rate and spatial
distribution of counts will be compared to pre-launch and SMOV data in
order to verify the nominal operation of the detector. Variations of
count rate as a function of orbital position will be analyzed to find
dependence of dark rate on proximity to the SAA. Dependence of dark
rate as function of time will also be tracked.

COS/NUV/FUV 11598

How Galaxies Acquire their Gas: A Map of Multiphase Accretion and
Feedback in Gaseous Galaxy Halos

We propose to address two of the biggest open questions in galaxy
formation - how galaxies acquire their gas and how they return it to
the IGM - with a concentrated COS survey of diffuse multiphase gas in
the halos of SDSS galaxies at z = 0.15 - 0.35. Our chief science goal
is to establish a basic set of observational facts about the physical
state, metallicity, and kinematics of halo gas, including the sky
covering fraction of hot and cold material, the metallicity of infall
and outflow, and correlations with galaxy stellar mass, type, and
color - all as a function of impact parameter from 10 - 150 kpc.
Theory suggests that the bimodality of galaxy colors, the shape of the
luminosity function, and the mass-metallicity relation are all
influenced at a fundamental level by accretion and feedback, yet these
gas processes are poorly understood and cannot be predicted robustly
from first principles. We lack even a basic observational assessment
of the multiphase gaseous content of galaxy halos on 100 kpc scales,
and we do not know how these processes vary with galaxy properties.
This ignorance is presently one of the key impediments to
understanding galaxy formation in general. We propose to use the
high-resolution gratings G130M and G160M on the Cosmic Origins
Spectrograph to obtain sensitive column density measurements of a
comprehensive suite of multiphase ions in the spectra of 43 z 1 QSOs
lying behind 43 galaxies selected from the Sloan Digital Sky Survey.
In aggregate, these sightlines will constitute a statistically sound
map of the physical state and metallicity of gaseous halos, and
subsets of the data with cuts on galaxy mass, color, and SFR will seek
out predicted variations of gas properties with galaxy properties. Our
interpretation of these data will be aided by state-of-the-art
hydrodynamic simulations of accretion and feedback, in turn providing
information to refine and test such models. We will also use Keck,
MMT, and Magellan (as needed) to obtain optical spectra of the QSOs to
measure cold gas with Mg II, and optical spectra of the galaxies to
measure SFRs and to look for outflows. In addition to our other
science goals, these observations will help place the Milky Way's
population of multiphase, accreting High Velocity Clouds (HVCs) into a
global context by identifying analogous structures around other
galaxies. Our program is designed to make optimal use of the unique
capabilities of COS to address our science goals and also generate a
rich dataset of other absorption-line systems.

FGS 12316

HST/FGS Astrometric Search for Young Planets Around Beta Pic and AU
Mic

AU Mic is a nearby Vega-type debris disk stars. Its disk system has
been spatially resolved in exquisite detail, predominantly via the ACS
coronagraph and WFPC-2 cameras onboard HST. These images exhibit a
wealth of morphological features which provide compelling indirect
evidence that AU Mic likely harbors short-period planetary body(ies).
We propose to use the superlative astrometric capabilities of HST/FGS
to directly detect these planets, hence provide the first direct
planet detection in a Vega-type system whose disk has been imaged at
high spatial resolution.

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 11721

Verifying the Utility of Type Ia Supernovae as Cosmological Probes:
Evolution and Dispersion in the Ultraviolet Spectra

The study of distant type Ia supernova (SNe Ia) offers the most
practical and immediate discriminator between popular models of dark
energy. Yet fundamental questions remain over possible
redshift-dependent trends in their observed and intrinsic properties.
High-quality Keck spectroscopy of a representative sample of 36
intermediate redshift SNe Ia has revealed a surprising, and
unexplained, diversity in their rest-frame UV fluxes. One possible
explanation is hitherto undiscovered variations in the progenitor
metallicity. Unfortunately, this result cannot be compared to local UV
data as only two representative SNe Ia have been studied near maximum
light. Taking advantage of two new `rolling searches' and the
restoration of STIS, we propose a non-disruptive TOO campaign to
create an equivalent comparison local sample. This will allow us to
address possible evolution in the mean UV spectrum and its diversity,
an essential precursor to the study of SNe beyond z~1.

STIS/CCD/MA2 11568

A SNAPSHOT Survey of the Local Interstellar Medium: New NUV
Observations of Stars with Archived FUV Observations

We propose to obtain high-resolution STIS E230H SNAP observations of
MgII and FeII interstellar absorption lines toward stars within 100
parsecs that already have moderate or high-resolution far-UV (FUV),
900-1700 A, observations available in the MAST Archive. Fundamental
properties, such as temperature, turbulence, ionization, abundances,
and depletions of gas in the local interstellar medium (LISM) can be
measured by coupling such observations. Due to the wide spectral range
of STIS, observations to study nearby stars also contain important
data about the LISM embedded within their spectra. However, unlocking
this information from the intrinsically broad and often saturated FUV
absorption lines of low-mass ions, (DI, CII, NI, OI), requires first
understanding the kinematic structure of the gas along the line of
sight. This can be achieved with high resolution spectra of high-mass
ions, (FeII, MgII), which have narrow absorption lines, and can
resolve each individual velocity component (interstellar cloud). By
obtaining short (~10 minute) E230H observations of FeII and MgII, for
stars that already have moderate or high- resolution FUV spectra, we
can increase the sample of LISM measurements, and thereby expand our
knowledge of the physical properties of the gas in our galactic
neighborhood. STIS is the only instrument capable of obtaining the
required high resolution data now or in the foreseeable future.

STIS/MA1/MA2 11857

STIS Cycle 17 MAMA Dark Monitor

This proposal monitors the behavior of the dark current in each of the
MAMA detectors.

The basic monitor takes two 1380s ACCUM darks each week with each
detector. However, starting Oct 5, pairs are only included for weeks
that the LRP has external MAMA observations planned. The weekly pairs
of exposures for each detector are linked so that they are taken at
opposite ends of the same SAA free interval. This pairing of exposures
will make it easier to separate long and short term temporal
variability from temperature dependent changes.

For both detectors, additional blocks of exposures are taken once
every six months. These are groups of five 1314s FUV-MAMA Time-Tag
darks or five 3x315s NUV ACCUM darks distributed over a single
SAA-free interval. This will give more information on the brightness
of the FUV MAMA dark current as a function of the amount of time that
the HV has been on, and for the NUV MAMA will give a better measure of
the short term temperature dependence.

WFC3/ACS/UVIS/IR 11570

Narrowing in on the Hubble Constant and Dark Energy

A measurement of the Hubble constant to a precision of a few percent
would be a powerful aid to the investigation of the nature of dark
energy and a potent "end-to end" test of the present cosmological
model. In Cycle 15 we constructed a new streamlined distance ladder
utilizing high- quality type Ia supernova data and observations of
Cepheids with HST in the near-IR to minimize the dominant sources of
systematic uncertainty in past measurements of the Hubble constant and
reduce its total uncertainty to a little under 5%. Here we propose to
exploit this new route to reduce the remaining uncertainty by more
than 30%, translating into an equal reduction in the uncertainty of
the equation of state of dark energy. We propose three sets of
observations to reach this goal: a mosaic of NGC 4258 with WFC3 in
F160W to triple its sample of long period Cepheids, WFC3/F160W
observations of the 6 ideal SN Ia hosts to triple their samples of
Cepheids, and observations of NGC 5584 the host of a new SN Ia, SN
2007af, to discover and measure its Cepheids and begin expanding the
small set of SN Ia luminosity calibrations. These observations would
provide the bulk of a coordinated program aimed at making the
measurement of the Hubble constant one of the leading constraints on
dark energy.

WFC3/IR 11591

Are Low-Luminosity Galaxies Responsible for Cosmic Reionization?

Our group has demonstrated that massive clusters, acting as powerful
cosmic lenses, can constrain the abundance and properties of
low-luminosity star-forming sources beyond z~6; such sources are
thought to be responsible for ending cosmic reionization. The large
magnification possible in the critical regions of well-constrained
clusters brings sources into view that lie at or beyond the limits of
conventional exposures such as the UDF. We have shown that the
combination of HST and Spitzer is particularly effective in delivering
the physical properties of these distant sources, constraining their
mass, age and past star formation history. Indirectly, we therefore
gain a valuable glimpse to yet earlier epochs. Recognizing the result
(and limitations) of blank field surveys, we propose a systematic
search through 10 lensing clusters with ACS/F814W and
WFC3/[F110W+F160W] (in conjunction with existing deep IRAC data). Our
goal is to measure with great accuracy the luminosity function at z~7
over a range of at least 3 magnitude, based on the identification of
about 50 lensed galaxies at 6.5z8. Our survey will mitigate cosmic
variance and extend the search both to lower luminosities and, by
virtue of the WFC3/IRAC combination, to higher redshift. Thanks to the
lensing amplification spectroscopic follow-up will be possible and
make our findings the most robust prior to the era of JWST and the
ELTs.

WFC3/IR 11666

Chilly Pairs: A Search for the Latest-type Brown Dwarf Binaries and
the Prototype Y Dwarf

We propose to use HST/WFC3 to image a sample of 27 of the nearest (
20 pc) and lowest luminosity T-type brown dwarfs in order to identify
and characterize new very low mass binary systems. Only 3 late-type T
dwarf binaries have been found to date, despite that fact that these
systems are critical benchmarks for evolutionary and atmospheric
models at the lowest masses. They are also the most likely systems to
harbor Y dwarf companions, an as yet unpopulated putative class of
very cold (T 600 K) brown dwarfs. Our proposed program will more
than double the number of T5-T9 dwarfs imaged at high resolution, with
an anticipated yield of ~5 new binaries with initial characterization
of component spectral types. We will be able to probe separations
sufficient to identify systems suitable for astrometric orbit and
dynamical mass measurements. We also expect one of our discoveries to
contain the first Y-type brown dwarf. Our proposed program complements
and augments ongoing ground-based adaptive optics surveys and provides
pathway science for JWST.

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/UV/ACS/WFC 11636

First Resolved Imaging of Escaping Lyman Continuum

The emission from star-forming galaxies appears to be responsible for
reionization of the universe at z 6. However, the models that
attempt to describe the detailed impact of high-redshift galaxies on
the surrounding inter-galactic medium (IGM) are strongly dependent
upon several uncertain parameters. Perhaps the most uncertain is the
fraction of HI-ionizing photons produced by young stars that escape
into the IGM. Most attempts to measure this "escape fraction" have
produced null results. Recently, a small subset of z~3 Lyman Break
Galaxies (LBGs) has been found exhibiting large escape fractions. It
remains unclear however, what differentiates them from other LBGs.
Several models attempt to explain how such a large fraction of
ionizing continuum can escape through the HI and dust in the ISM (eg.
"chimneys" created by SNe winds, globular cluster formation, etc.),
each producing unique signatures which can be observed with resolved
imaging of the escaping Lyman continuum. To date, there are only six
LBGs with individual detections of escaping Lyman continuum at any
redshift. We propose a single deep, high resolution WFC3/UVIS image of
the ionizing continuum (F336W) and the rest-frame UV/optical
(F606W/F814W/F160W) of five of these six LBGs with large escape
fractions. These LBGs have a high surface density and large escape
fractions, and lie at the optimal redshift for Lyman continuum imaging
with UVIS filters, making our sample especially suitable for
follow-up. With these data we will discern the mechanisms responsible
for producing large escape fractions, and therefore gain insight into
the process of reionization.

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.

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