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============================================================================== TOPIC: Daily Report #5039
== 1 of 1 == Date: Wed, Feb 24 2010 7:56Â am From: "Cooper, Joe"
HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY REPORT #5039
PERIOD COVERED: 5am February 23 - 5am February 24, 2010 (DOY 054/10:00z-055/10:00z)
OBSERVATIONS SCHEDULED
COS/NUV/FUV 11522
COS-GTO: Star Formation/Lyman-Alpha
A sample of 20 star-forming galaxies will be observed with COS G130M The galaxies were selected from the Kitt Peak International Spectroscopic Survey (KISSR) data release and cover a broad range of luminosity, oxygen abundance, and reddening The goal of the program is to characterize the Lyman-alpha properties and establish correlations with fundamental galaxy properties Each galaxy will be observed for one orbit
COS/NUV/FUV 11698
The Structure and Dynamics of Virgo's Multi-Phase Intracluster Medium
The dynamical flows of the intracluster medium (ICM) are largely unknown We propose to map the spatial and kinematic distribution of the warm ICM of the nearby Virgo cluster using the Cosmic Origins Spectrograph 15 sightlines at a range of impact parameters within the virial radius of the cluster (0 2 - 1 7 Mpc) will be probed for Lyman-alpha absorption and the data compared to blind HI, dust and x-ray surveys to create a multi-phase map of the cluster's ICM Absorption line sightlines are commonly 40-100 kpc from a galaxy, allowing the flow of baryons between galaxies and the ICM to be assessed The velocity distribution of the absorbers will be directly compared to simulations and used to constrain the turbulent motions of the ICM This proposal will result in the first map of a cluster's warm ICM and provide important tests for our theoretical understanding of cluster formation and the treatment of gas cooling in cosmological simulations
COS/NUV/FUV 11718
The Stellar Halos of Dwarf Galaxies
The metal-poor stellar halo is the oldest extended structure in the Galaxy Such halos are thought to form through hierarchical merging, and contain stars pulled from accreted subhalos The diffuse stellar halo therefore stores information about the prop reties of the accreted galaxies (i e , their orbits, stellar masses, and metallicities) It is therefore unsurprising that stellar halos have become a popular probe of the early epoch of galaxy formation
Almost all current work on stellar halos has focused on massive galaxies, however We propose to extend the work on stellar halos to much lower mass scales, by studying the halos of faint dwarf galaxies By taking halo studies into the dwarf galaxy regime, we can probe exceptionally small mass scales for the accreted halos At these mass scales the effects of reionization and supernova feedback have the largest impact on the galaxy population Stellar halos of dwarf galaxies are therefore a sensitive probe of the key processes needed to resolve the lack of substructure observed at low masses
We are requesting two far-field ACS pointings for the three closest isolated nearby dwarf irregular galaxies whose inner halos have already been mapped with the ACS Nearby Galaxy Survey Treasury These outer fields will allow us to trace the halo out to roughly half the virial radius, further than any previous study We will use the resulting distribution of halo stars (1) to unambiguously measure the structure of the stellar halo, with minimal contamination from the main galaxy; (2) to constrain the flattening of the stellar halo; (3) to measure the metallicity of halo stars as a function of radius; (4) to correlate any changes in halo profile with changes in metallicity The resulting data will constrain models of halo accretion and the epoch of reionization
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 12046
COS FUV DCE Memory Dump
Whenever the FUV detector high voltage is on, count rate and current draw information is collected, monitored, and saved to DCE memory Every 10 msec the detector samples the currents from the HV power supplies (HVIA, HVIB) and the AUX power supply (AUXI) The last 1000 samples are saved in memory, along with a histogram of the number of occurrences of each current value
In the case of a HV transient (known as a "crackle" on FUSE), where one of these currents exceeds a preset threshold for a persistence time, the HV will shut down, and the DCE memory will be dumped and examined as part of the recovery procedure However, if the current exceeds the threshold for less than the persistence time (a "mini-crackle" in FUSE parlance), there is no way to know without dumping DCE memory By dumping and examining the histograms regularly, we will be able to monitor any changes in the rate of "mini-crackles" and thus learn something about the state of the detector
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
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/ACS/UVIS 11684
The First Proper Motion Measurement for M31: Dynamics and Mass of the Local Group
We will perform observations to determine the proper motion of the Andromeda galaxy M31, which has been sought for almost a century without success While challenging, this measurement has now become possible due to the availability of existing deep ACS/WFC images of several M31 fields The requested second epoch images will yield the average shift of the M31 stars with respect to compact galaxies in the background Our observing strategy uses six different fields (three primary and three coordinated parallel) with two different instruments (ACS and WFC3) to provide a maximum handle on possible systematic effects The expected result will be sufficiently accurate to: (a) discriminate between different histories for the dynamics of the Local Group; (b) constrain the mass distribution of the Local Group; (c) determine the details of the expected future merger between M31 and the Milky Way; (d) infer the past interaction history between M31 and M33; (e) constrain the internal proper motion kinematics of the M31 spheroid, outer disk, and tidal stream; and (f) obtain a pilot estimate of the M31 distance through the method of rotational parallax
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
5 WFC3/IR 11666 Chilly Pairs: A Search for the Latest-type Brown Dwarf Binaries and
the Prototype Y Dwarf We propose to use HST/NICMOS 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/UVIS 11589 Hypervelocity Stars as Unique Probes of the Galactic Center and Outer
Halo We propose to obtain high-resolution images of 11 new hypervelocity
stars in the Galactic halo in order to establish the first-epoch
astrometric frame, as a part of a long-term program to measure precise
proper motions in an absolute inertial frame
The origin of these
recently discovered stars with extremely large positive radial
velocities, in excess of the escape speed from the Galaxy, is
consistent only with being ejected from the deep potential well of the
massive black hole at the Galactic center
Reconstructing the full
three-dimensional space motion of the hypervelocity stars, through
astrometric proper motions, provides a unique opportunity to measure
the shape and orientation of the triaxial dark matter halo
The
hypervelocity stars allow determination of the Galactic potential out
to 120 kpc, independently of and at larger distances than is afforded
by tidal streams of satellite galaxies such as the Sagittarius dSph
galaxy
Proper motions of the full set of hypervelocity stars will
provide unique constraints on massive star formation in the
environment of the Galactic center and on the history of stellar
ejection by the supermassive black hole
We request one orbit with
WFC3 for each of the 11 hypervelocity stars to establish their current
positions relative to background galaxies
We request a repeated
observation of these stars in Cycle 19, which will conclusively
measure the astrometric proper motions
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)
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) FGS GSAcq 10 10
FGS REAcq 7 7
OBAD with Maneuver 7 7 SIGNIFICANT EVENTS: (None) ==============================================================================
TOPIC: Daily Report #5040 == 1 of 1 ==
Date: Thurs, Feb 25 2010 9:14Â am
From: "Cooper, Joe" HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science DAILY REPORT #5040 PERIOD COVERED: 5am February 24 - 5am February 25, 2010 (DOY 055/10:00z-056/10:00z) OBSERVATIONS SCHEDULED ACS/WFC 11995 CCD Daily Monitor (Part 2) 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 320 orbits (20 weeks) from 1 February
2010 to 20 June 2010
COS/NUV/FUV 11718 The Stellar Halos of Dwarf Galaxies The metal-poor stellar halo is the oldest extended structure in the
Galaxy
Such halos are thought to form through hierarchical merging,
and contain stars pulled from accreted subhalos
The diffuse stellar
halo therefore stores information about the prop reties of the
accreted galaxies (i
e
, their orbits, stellar masses, and
metallicities)
It is therefore unsurprising that stellar halos have
become a popular probe of the early epoch of galaxy formation
Almost all current work on stellar halos has focused on massive
galaxies, however
We propose to extend the work on stellar halos to
much lower mass scales, by studying the halos of faint dwarf galaxies
By taking halo studies into the dwarf galaxy regime, we can probe
exceptionally small mass scales for the accreted halos
At these mass
scales the effects of reionization and supernova feedback have the
largest impact on the galaxy population
Stellar halos of dwarf
galaxies are therefore a sensitive probe of the key processes needed
to resolve the lack of substructure observed at low masses
We are requesting two far-field ACS pointings for the three closest
isolated nearby dwarf irregular galaxies whose inner halos have
already been mapped with the ACS Nearby Galaxy Survey Treasury
These
outer fields will allow us to trace the halo out to roughly half the
virial radius, further than any previous study
We will use the
resulting distribution of halo stars (1) to unambiguously measure the
structure of the stellar halo, with minimal contamination from the
main galaxy; (2) to constrain the flattening of the stellar halo; (3)
to measure the metallicity of halo stars as a function of radius; (4)
to correlate any changes in halo profile with changes in metallicity
The resulting data will constrain models of halo accretion and the
epoch of reionization
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
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 11189 Probing the Early Universe with GRBs Cosmology is beginning to constrain the nature of the earliest stars
and galaxies to form in the Universe, but direct observation of
galaxies at z>6 remains highly challenging due to their scarcity,
intrinsically small size, and high luminosity distance
GRB
afterglows, thanks to their extreme luminosities, offer the
possibility of circumventing these normal constraints by providing
redshifts and spectral information which couldn't be obtained through
direct observation of the host galaxies themselves
In addition, the
association of GRBs with massive stars means that they are an
indicator of star formation, and that their hosts are likely
responsible for a large proportion of the ionizing radiation during
that era
Our collaboration is conducting a campaign to rapidly
identify and study candidate very high redshift bursts, bringing to
bear a network of 2, 4 and 8m telescopes with near-IR instrumentation
Swift has proven capable of detecting faint, distant GRBs, and
reporting accurate positions for many bursts in near real-time
Here
we propose to continue our HST program of targeting GRBs at z~6 and
above
HST is crucial to this endeavor, allowing us (a) to
characterize the basic properties, such as luminosity and color, and
in some cases morphologies, of the hosts, which is essential to
understanding these primordial galaxies and their relationship to
other galaxy populations; and (b) to monitor the late time afterglows
and hence compare them to lower-z bursts and test the use of GRBs as
standard candles
WFC3/IR 11719 A Calibration Database for Stellar Models of Asymptotic Giant Branch
Stars Studies of galaxy formation and evolution rely increasingly on the
interpretation and modeling of near-infrared observations
At these
wavelengths, the brightest stars are intermediate mass asymptotic
giant branch (AGB) stars
These stars can contribute nearly 50% of the
integrated luminosity at near infrared and even optical wavelengths,
particularly for the younger stellar populations characteristic of
high-redshift galaxies (z>1)
AGB stars are also significant sources
of dust and heavy elements
Accurate modeling of AGB stars is
therefore of the utmost importance
The primary limitation facing current models is the lack of useful
calibration data
Current models are tuned to match the properties of
the AGB population in the Magellanic Clouds, and thus have only been
calibrated in a very narrow range of sub-solar metallicities
Preliminary observations already suggest that the models are
overestimating AGB lifetimes by factors of 2-3 at lower metallicities
At higher (solar) metallicities, there are no appropriate observations
for calibrating the models
We propose a WFC3/IR SNAP survey of nearby galaxies to create a large
database of AGB populations spanning the full range of metallicities
and star formation histories
Because of their intrinsically red
colors and dusty circumstellar envelopes, tracking the numbers and
bolometric fluxes of AGB stars requires the NIR observations we
propose here
The resulting observations of nearby galaxies with deep
ACS imaging offer the opportunity to obtain large (100-1000's)
complete samples of AGB stars at a single distance, in systems with
well-constrained star formation histories and metallicities
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 12019 After the Fall: Fading AGN in Post-starburst Galaxies We propose joint Chandra and HST observations of an extraordinary
sample of 12 massive post-starburst galaxies at z=0
4-0
8 that are in
the short-lived evolution phase a few 100 Myr after the peak of
merger-driven star formation and AGN activity
We will use the data to
measure X-ray luminosities, black hole masses, and accretion rates;
and with the accurate "clocks" provided by post-starburst stellar
populations, we will directly test theoretical models that predict a
power-law decay in the AGN light curve
We will also test whether star
formation and black hole accretion shut down in lock-step, quantify
whether the black holes transition to radiatively inefficient
accretion states, and constrain the observational signatures of black
hole mergers
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 11595 Turning Out the Light: A WFC3 Program to Image z>2 Damped Lyman Alpha
Systems We propose to directly image the star-forming regions of z>2 damped
Lya systems (DLAs) using the WFC3/UVIS camera on the Hubble Space
Telescope
In contrast to all previous attempts to detect the galaxies
giving rise to high redshift DLAs, we will use a novel technique that
completely removes the glare of the background quasar
Specifically,
we will target quasar sightlines with multiple DLAs and use the higher
redshift DLA as a ``blocking filter'' (via Lyman limit absorption) to
eliminate all FUV emission from the quasar
This will allow us to
carry out a deep search for FUV emission from the lower redshift DLA,
shortward of the Lyman limit of the higher redshift absorber
The
unique filter set and high spatial resolution afforded by WFC3/UVIS
will then enable us to directly image the lower redshift DLA and thus
estimate its size, star- formation rate and impact parameter from the
QSO sightline
We propose to observe a sample of 20 sightlines,
selected primarily from the SDSS database, requiring a total of 40 HST
orbits
The observations will allow us to determine the first FUV
luminosity function of high redshift DLA galaxies and to correlate the
DLA galaxy properties with the ISM characteristics inferred from
standard absorption-line analysis to significantly improve our
understanding of the general DLA population
WFC3/UVIS 11786 HST Observations of Astrophysically Important Visual Binaries This is a continuation of a project begun in Cycle 7 and continued up
through Cycle 14
The program consists of annual FGS or WFPC2
observations of three visual binary stars that will yield fundamental
astrophysical results, once their orbits and masses are determined
In
Cycle 17 we are changing WFPC2 to WFC3
Our targets are the following: (1) Procyon (P = 40
9 yr), for which
our first WFPC2 images yielded an extremely accurate angular
separation of the bright F star and its much fainter white- dwarf
companion
Combined with ground-based astrometry of the bright star,
our observation significantly revised downward the derived masses, and
brought Procyon A into much better agreement with theoretical
evolutionary masses for the first time
With the continued monitoring
proposed here, we will obtain masses to an accuracy of better than 1%,
providing a testbed for theories of both Sun-like stars and white
dwarfs
(2) G 107-70, a close double white dwarf (P = 18
5 yr) that
promises to add two accurate masses to the tiny handful of white-dwarf
masses that are directly known from dynamical measurements
(3) Mu Cas
(P = 20
8 yr), a famous nearby metal-deficient G dwarf for which
accurate masses will lead to the stars' helium contents, with
cosmological implications
For all three stars, we will also be
setting increasingly stringent limits on the presence of
planetary-mass bodies in the systems
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
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) FGS GSAcq 7 7
FGS REAcq 9 9
OBAD with Maneuver 4 4 SIGNIFICANT EVENTS: (None) ============================================================================== You received this message because you are subscribed to the Google Groups "sci
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