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============================================================================== TOPIC: Daily Report #5065
== 1 of 1 == Date: Thurs, Apr 1 2010 6:37 am From: "Bassford, Lynn"
HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY REPORT #5065
PERIOD COVERED: 5am March 31 - 5am April 1, 2010 (DOY 090/09:00z-091/09:00z)
OBSERVATIONS SCHEDULED
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
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
ACS/WFC3 11599
Distances of Planetary Nebulae from SNAPshots of Resolved Companions
Reliable distances to individual planetary nebulae (PNe) in the Milky Way are needed to advance our understanding of their spatial distribution, birthrates, influence on galactic chemistry, and the luminosities and evolutionary states of their central stars (CSPN) Few PNe have good distances, however One of the best ways to remedy this problem is to find resolved physical companions to the CSPN and measure their distances by photometric main-sequence fitting We have previously used HST to identify and measure probable companions to 10 CSPN, based on angular separations and statistical arguments only We now propose to use HST to re-observe 48 PNe from that program for which additional companions are possibly present We then can use the added criterion of common proper motion to confirm our original candidate companions and identify new ones in cases that could not confidently be studied before We will image the region around each CSPN in the V and I bands, and in some cases in the B band Field stars that appear close to the CSPN by chance will be revealed by their relative proper motion during the 13+ years since our original survey, leaving only genuine physical companions in our improved and enlarged sample This study will increase the number of Galactic PNe with reliable distances by 50 percent and improve the distances to PNe with previously known companions
COS/FUV 11897
FUV Spectroscopic Sensitivity Monitoring
The purpose of this proposal is to monitor sensitivity in each FUV grating mode to detect any changes due to contamination or other causes
COS/NUV 11561
An Intensive COS Spectroscopic Study of the Planetary Debris Disks Around two Warm White Dwarfs
It is very likely that the gas giants in our Solar system will survive the evolution of the Sun into a white dwarf, and the same is thought to be generally true for Jovian planets around solar-like stars if their initial orbits are wider than ~3AU Despite this prediction, no unambiguous detection of a planet around a white dwarf has been announced so far However, over the past few years, about a dozen white dwarfs have been identified which host metal-rich debris disks that are thought to stem from the tidal disruption of asteroids In most cases the debris disks are observed in the form of an infrared flux excess, and offer relatively little diagnostic potential for the study of their structure We have discovered three warm (T~20000K) white dwarfs with metal-rich debris disks in a gaseous phase which display strong double-peaked CaII emission lines in the I-band and weak Fe 5169A emission The line profiles can be modeled in terms of Keplerian disks with an extension of ~1Rsun around the white dwarfs Photospheric MgII 4481A absorption demonstrates that the white dwarfs are accreting from the debris disks Besides these spectral features, the optical wavelength range is devoid of other useful metal transitions Here, we propose an intensive spectroscopic ultraviolet study of these systems, which will provide (a) ~1000 photospheric absorption lines of 15 chemical elements, allowing an accurate abundance study of the material accreted from the debris disks, and (b) ~2 dozen additional emission lines of Mg, Cr, Ti, and Fe that will provide detailed insight into the dynamical, thermal, and density structure of these exo-planetary debris disks
COS/NUV 11894
NUV Detector Dark Monitor
The purpose of this proposal is to measure the NUV detector dark rate by taking long science exposures with no light on 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/WFC3/UVIS/IR 11520
COS-GTO: QSO Absorbers, Galaxies and Large-Scale Structures in the Local Universe
This is a program to probe the large scale structure of baryons in the universe, including addressing questions of baryon fraction, physical conditions and relationships between absorbers and large-scale structures of galaxies Besides these specific goals, this proposed GTO program also probes a large enough total path length in Ly alpha and OVI to add significantly to what STIS/FUSE has already observed Several Galactic High Velocity Cloud Complexes also are probed by these sightlines, particularly the M Complex The total path length of this proposed program for Ly alpha large-scale structure surveys is delta_z~5 5
We have selected a variety of targets to address these questions, under the following subcategories:
Target 8 bright BL Lac objects to search for low contrast Ly alpha absorbers from the warm- hot interstellar medium (WHIM)
Ly alpha cloud sizes: The targets are a bright AGN pair which yield tangential distance separations of 100--500 kpc at z=0 01--0 05, where galaxy surveys are excellent This pair has two filaments and two voids in this distance range
Probes of starburst outflows: The targets are bright AGN, <= 100 kpc in projection out of the minor axis of nearby starburst galaxies
A large galaxy's gaseous halo: Three probes of the kinematics and metallicity of a single L* galaxy halo These observations includes G130M, G160M exposures at SNR~20 and G285M at 2850A and SNR~10 for MgII The 2L* galaxy, ESO 157-G049 (cz=1678 km/s), being probed by these sightlines has an available H I 21cm map from ATCA, H alpha imaging from CTIO and long- slit spectra from MSSSO
Dwarf galaxy winds: These targets probe the kinematics and metallicities of outflows from active and inactive (in terms of star formation) dwarfs
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/CC/MA 11516
COS-GTO: Cold ISM
With the COS, we will be able to observe interstellar spectra in a new regime, translucent clouds, for atomic, ionic, and molecular lines and bands, and extinction curves The COS will allow us to observe stars with total visual extinctions up to 10 magnitudes, and the grain size indicator Rv up to 4 5 In translucent clouds we expect to see the transition from neutral and ionized carbon to mostly C I, and then from there, we should expect to see carbon increasingly locked up in molecular form, as CO Other species are expected to make similar transitions, so we should find detectable abundances of molecules such as H2O, OH, CS, CH2, SiO, and others; also, lower ionization fractions of the metallic elements - and higher depletions of those elements as well Given that we expect to find higher depletions, we should see an altered grain size distribution, which may show up in the extinction curves, probably as lower far-UV extinction than in diffuse clouds Finally, we will search for neutral PAHs in absorption, as diffuse bands in the UV, paralleling the optical DIBs (which are thought by some scientists to be formed by singly-ionized PAHs) In translucent clouds, models show that the PAHs will be neutral, not in cationic form
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/UVIS/IR 11909
UVIS Hot Pixel Anneal
The on-orbit radiation environment of WFC3 will continually generate new hot pixels This proposal performs the procedure required for repairing those hot pixels in the UVIS CCDs During an anneal, the two-stage thermo-electric cooler (TEC) is turned off and the four-stage TEC is used as a heater to bring the UVIS CCDs up to ~20 deg C As a result of the CCD warmup, a majority of the hot pixels will be fixed; previous instruments such as WFPC2 and ACS have seen repair rates of about 80% Internal UVIS exposures are taken before and after each anneal, to allow an assessment of the procedure's effectiveness in WFC3, provide a check of bias, global dark current, and hot pixel levels, as well as support hysteresis (bowtie) monitoring and CDBS reference file generation One IR dark is taken after each anneal, to provide a check of the IR detector
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated )
HSTARS:
12234 ? OBAD(1,3) at 091/07:56:38z failed due to too few stars on FHST#1 GSAcq(1,2,1) at 091/08:02:11z was successful
COMPLETED OPS REQUEST: (None)
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL
FGS GSAcq 9 9 FGS REAcq 7 7 OBAD with Maneuver 5 4
SIGNIFICANT EVENTS: (None)
============================================================================== TOPIC: Daily Report #5066
== 1 of 1 == Date: Fri, Apr 2 2010 8:42 am From: "Cooper, Joe"
HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY REPORT #5066
PERIOD COVERED: 5am April 1 - 5am April 2, 2010 (DOY 091/09:00z-092/09:00z)
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
COS/FUV 11897
FUV Spectroscopic Sensitivity Monitoring
The purpose of this proposal is to monitor sensitivity in each FUV grating mode to detect any changes due to contamination or other causes
COS/FUV/STIS/CCD/MA1 11592
Testing the Origin(s) of the Highly Ionized High-Velocity Clouds: A Survey of Galactic Halo Stars at z>3 kpc
Cosmological simulation predicts that highly ionized gas plays an
important role in the formation and evolution of galaxies and their
interplay with the intergalactic medium
The NASA HST and FUSE
missions have revealed high-velocity CIV and OVI absorption along
extragalactic sightlines through the Galactic halo
These highly
ionized high-velocity clouds (HVCs) could cover 85% of the sky and
have a detection rate higher than the HI HVCs
Two competing, equally
exciting, theories may explain the origin of these highly ionized
HVCs: 1) the "Galactic" theory, where the HVCs are the result of
feedback processes and trace the disk-halo mass exchange, perhaps
including the accretion of matter condensing from an extended corona;
2) the "Local Group" theory, where they are part of the local warm-hot
intergalactic medium, representing some of the missing baryonic matter
of the Universe
Only direct distance determinations can discriminate
between these models
Our group has found that some of these highly
ionized HVCs have a Galactic origin, based on STIS observations of one
star at z<5
3 kpc
We propose an HST FUV spectral survey to search for
and characterize the high velocity NV, CIV, and SiIV interstellar
absorption toward 24 stars at much larger distances than any previous
searches (4 COS/NUV 11561 An Intensive COS Spectroscopic Study of the Planetary Debris Disks
Around two Warm White Dwarfs It is very likely that the gas giants in our Solar system will survive
the evolution of the Sun into a white dwarf, and the same is thought
to be generally true for Jovian planets around solar-like stars if
their initial orbits are wider than ~3AU
Despite this prediction, no
unambiguous detection of a planet around a white dwarf has been
announced so far
However, over the past few years, about a dozen
white dwarfs have been identified which host metal-rich debris disks
that are thought to stem from the tidal disruption of asteroids
In
most cases the debris disks are observed in the form of an infrared
flux excess, and offer relatively little diagnostic potential for the
study of their structure
We have discovered three warm (T~20000K)
white dwarfs with metal-rich debris disks in a gaseous phase which
display strong double-peaked CaII emission lines in the I-band and
weak Fe 5169A emission
The line profiles can be modeled in terms of
Keplerian disks with an extension of ~1Rsun around the white dwarfs
Photospheric MgII 4481A absorption demonstrates that the white dwarfs
are accreting from the debris disks
Besides these spectral features,
the optical wavelength range is devoid of other useful metal
transitions
Here, we propose an intensive spectroscopic ultraviolet
study of these systems, which will provide (a) ~1000 photospheric
absorption lines of 15 chemical elements, allowing an accurate
abundance study of the material accreted from the debris disks, and
(b) ~2 dozen additional emission lines of Mg, Cr, Ti, and Fe that will
provide detailed insight into the dynamical, thermal, and density
structure of these exo-planetary debris disks
COS/NUV 11894 NUV Detector Dark Monitor The purpose of this proposal is to measure the NUV detector dark rate
by taking long science exposures with no light on 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
FGS 11704 The Ages of Globular Clusters and the Population II Distance Scale Globular clusters are the oldest objects in the universe whose age can
be accurately determined
The dominant error in globular cluster age
determinations is the uncertain Population II distance scale
We
propose to use FGS 1R to obtain parallaxes with an accuracy of 0
2
milliarcsecond for 9 main sequence stars with [Fe/H] < -1
5
This will
determine the absolute magnitude of these stars with accuracies of
0
04 to 0
06mag
This data will be used to determine the distance to
24 metal-poor globular clusters using main sequence fitting
These
distances (with errors of 0
05 mag) will be used to determine the ages
of globular clusters using the luminosity of the subgiant branch as an
age indicator
This will yield absolute ages with an accuracy of 5%,
about a factor of two improvement over current estimates
Coupled with
existing parallaxes for more metal-rich stars, we will be able to
accurately determine the age for globular clusters over a wide range
of metallicities in order to study the early formation history of the
Milky Way and provide an independent estimate of the age of the
universe
The Hipparcos database contains only 1 star with [Fe/H] < -1
4 and an
absolute magnitude error less than 0
18 mag which is suitable for use
in main sequence fitting
Previous attempts at main sequence fitting
to metal-poor globular clusters have had to rely on theoretical
calibrations of the color of the main sequence
Our HST parallax
program will remove this source of possible systematic error and yield
distances to metal-poor globular clusters which are significantly more
accurate than possible with the current parallax data
The HST
parallax data will have errors which are 10 times smaller than the
current parallax data
Using the HST parallaxes, we will obtain main
sequence fitting distances to 11 globular clusters which contain over
500 RR Lyrae stars
This will allow us to calibrate the absolute
magnitude of RR Lyrae stars, a commonly used Population II distance
indicator
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/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/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 z>6 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 are: (1) Detect Lya
in ~100 galaxies with z>5
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
5 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/S/C 12097 Additional IR Subarray Dark Current Measurements (in support of GO
programs 11205, 11580) This proposal will produce IR dark images necessary to calibrate GO
science observations (already taken, see proposals 11205 and 11580)
that use observing modes not supported by the existing IR dark current
monitor (proposal 11929)
These modes are as follows:
SQ256SUB/SPARS100, SQ256SUB/SPARS200, SQ512SUB/SPARS10,
SQ512SUB/SPARS100, and SQ512SUB/SPARS200
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 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
WFC3/UVIS/IR 11909 UVIS Hot Pixel Anneal The on-orbit radiation environment of WFC3 will continually generate
new hot pixels
This proposal performs the procedure required for
repairing those hot pixels in the UVIS CCDs
During an anneal, the
two-stage thermo-electric cooler (TEC) is turned off and the
four-stage TEC is used as a heater to bring the UVIS CCDs up to ~20
deg
C
As a result of the CCD warm up, a majority of the hot pixels
will be fixed; previous instruments such as WFPC2 and ACS have seen
repair rates of about 80%
Internal UVIS exposures are taken before
and after each anneal, to allow an assessment of the procedure's
effectiveness in WFC3, provide a check of bias, global dark current,
and hot pixel levels, as well as support hysteresis (bowtie)
monitoring and CDBS reference file generation
One IR dark is taken
after each anneal, to provide a check of the IR detector
WFC3/UV 12077 Monitoring the Aftermath of an Asteroid Impact Event Our Director's Discretionary program (GO-12053) to image the newly
discovered object P/2010 A2 executed successfully on 2010 Jan 25 and
29 with spectacular results
Hubble has apparently borne witness to
the first detection of a collision in the asteroid belt
Hubble
imaging with the WFC3 has revealed an object unlike anything ever seen
before and with details impossible to detect with any other facility
We request 6 more orbits of Hubble time (1 orbit every 20 days over
the next few months, until the object enters Hubble's solar exclusion
zone in late-June 2010) to monitor the evolution of this remarkable
object and further clarify the nature of this event
These
observations may usher in a new era of searching for and
characterizing collisional events within the asteroid belt
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: 18837-0 - Null Genslew for proposal 12077 - slot 13 @ 091/1345z COMPLETED OPS NOTES: (None) FGS GSAcq 10 10
FGS REAcq 5 5
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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