HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #4925
PERIOD
COVERED: 5am September 4 - 5am September 8, 2009 (DOY 247/09:00z-251/09:00z)
OBSERVATIONS
SCHEDULED
WFC3/UVIS
11935
UVIS
G280 Wavelength Calibration
Wavelength
calibration of the UVIS G280 grism will be established using
observations
of the Wolf Rayet star WR14. Accompanying direct exposures
will
provide wavelength zeropoints for dispersed exposures. The
calibrations
will be obtained at the central position of each CCD chip
and
at the center of the UVIS field. No additional field- dependent
variations
will be obtained.
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
11912
UVIS
Internal Flats
This
proposal will be used to assess the stability of the flat field
structure
for the UVIS detector throughout the 15 months of Cycle 17.
The
data will be used to generate on- orbit updates for the delta-flat
field
reference files used in the WFC3 calibration pipeline, if
significant
changes in the flat structure are seen.
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
11907
UVIS
Cycle 17 Contamination Monitor
The
UV throughput of WFC3 during Cycle 17 is monitored via weekly
standard
star observations in a subset of key filters covering 200-600nm
and
F606W, F814W as controls on the red end. The data will provide a
measure
of throughput levels as a function of time and wavelength,
allowing
for detection of the presence of possible contaminants.
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).
COS/NUV
11896
NUV
Spectroscopic Sensitivity Monitoring
The
purpose of this proposal is to monitor sensitivity of each NUV
grating
mode to detect any changes due to contamination or other causes.
ACS/WFC3
11879
CCD
Daily Monitor (Part 1)
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 352 orbits (22 weeks) from 31 August 2009 to 31 January
2010.
WFC3/ACS/UVIS
11877
HST
Cycle 17 and Post-SM4 Optical Monitor
This
program is the Cycle 17 implementation of the HST Optical
Monitoring
Program.
The
36 orbits comprising this proposal will utilize ACS (Wide Field
Channel)
and WFC3 (UVIS Channel) to observe stellar cluster members in
parallel
with multiple exposures over an orbit. Phase retrieval
performed
on the PSF in each image will be used to measure primarily
focus,
with the ability to explore apparent coma, and astigmatism
changes
in WFC3.
The
goals of this program are to: 1) monitor the overall OTA focal
length
for the purposes of maintaining focus within science tolerances
2)
gain experience with the relative effectiveness of phase retrieval on
WFC3/UVIS
PSFs 3) determine focus offset between the imagers and
identify
any SI-specific focus behavior and dependencies
If
need is determined, future visits will be modified to interleave
WFC3/IR
channel and STIS/CCD focii measurements.
STIS/CCD
11855
STIS/CCD
Spectroscopic Sensitivity Monitor for Cycle 17
The
purpose of this proposal is to monitor the sensitivity of each CCD
grating
mode to detect any changes due to contamination or other causes.
STIS/CCD
11850
CCD
Sparse Field CTE Internal
CTE
measurements are made using the "internal sparse field test", along
the
parallel axis. The "Pos=" optional parameter, introduced during
Cycle
11, is used to provide off- center MSM positionings of some slits.
All
exposures are internals.
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.
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
11844
CCD
Dark Monitor Part 1
The
purpose of this proposal is to monitor the darks for the STIS CCD.
FGS
11706
The
Parallax of the Planet Host Star XO-3
We
will use HST+FGS to measure the parallax of the transiting planet
host
star XO 3. The resulting accurate distance measurement will provide
the
most accurate radius determination to date for this massive
extrasolar
planet (XO-3B), allowing us to critically test current giant
extrasolar
planet structure models. These observations will also
constrain
the amount of heating that may be produced inside XO-3B by
tides
raised on the planet as it moves through its 3.2 d-eccentric (e ~
0.22)
orbit.
WFC3/UVIS
11657
The
Population of Compact Planetary Nebulae in the Galactic Disk
We
propose to secure narrow- and broad-band images of compact planetary
nebulae
(PNe) in the Galactic Disk to study the missing link of the
early
phases of post-AGB evolution. Ejected AGB envelopes become PNe
when
the gas is ionized. PNe expand, and, when large enough, can be
studied
in detail from the ground. In the interim, only the HST
capabilities
can resolve their size, morphology, and central stars. Our
proposed
observations will be the basis for a systematic study of the
onset
of morphology. Dust properties of the proposed targets will be
available
through approved Spitzer/IRS spectra, and so will the
abundances
of the alpha-elements. We will be able thus to explore the
interconnection
of morphology, dust grains, stellar evolution, and
populations.
The target selection is suitable to explore the nebular and
stellar
properties across the Galactic Disk, and to set constraints on
the
galactic evolutionary models through the analysis of metallicity and
population
gradients.
WFC3/UVIS
11650
Mutual
Orbits, Colors, Masses, and Bulk Densities of 3 Cold Classical
Trans-Neptunian
Many
trans-neptunian objects (TNOs) have been found to be binary or
multiple
systems. As in other astrophysical settings, trans-neptunian
binaries
(TNBs) offer uniquely valuable information. Their mutual orbits
allow
the direct determination of their system masses, perhaps the most
fundamental
physical quantity of any astronomical object. Their
frequency
of occurrence and dynamical characteristics provide clues to
formation
conditions and evolution scenarios affecting both the binaries
and
their single neighbors. Combining masses with sizes, bulk densities
can
be measured. Densities constrain bulk composition and internal
structure,
key clues to TNO origins and evolution over time. Several TNB
bulk
densities have been determined, hinting at interesting trends. But
none
of them belongs to the Cold Classical sub-population, the one group
of
TNOs with demonstrably distinct physical characteristics. Two
top-priority
Spitzer programs will soon observe and measure the sizes of
3
Cold Classical TNBs. This proposal seeks to determine the mutual
orbits
and thus masses of these systems, enabling computation of their
densities.
WFC3/UVIS/IR
11644
A
Dynamical-Compositional Survey of the Kuiper Belt: A New Window Into
the
Formation of the Outer Solar System
The
eight planets overwhelmingly dominate the solar system by mass, but
their
small numbers, coupled with their stochastic pasts, make it
impossible
to construct a unique formation history from the dynamical or
compositional
characteristics of them alone. In contrast, the huge
numbers
of small bodies scattered throughout and even beyond the
planets,
while insignificant by mass, provide an almost unlimited number
of
probes of the statistical conditions, history, and interactions in
the
solar system. To date, attempts to understand the formation and
evolution
of the Kuiper Belt have largely been dynamical simulations
where
a hypothesized starting condition is evolved under the
gravitational
influence of the early giant planets and an attempt is
made
to reproduce the current observed populations. With little
compositional
information known for the real Kuiper Belt, the test
particles
in the simulation are free to have any formation location and
history
as long as they end at the correct point. Allowing compositional
information
to guide and constrain the formation, thermal, and
collisional
histories of these objects would add an entire new dimension
to
our understanding of the evolution of the outer solar system. While
ground
based compositional studies have hit their flux limits already
with
only a few objects sampled, we propose to exploit the new
capabilities
of WFC3 to perform the first ever large-scale
dynamical-compositional
study of Kuiper Belt Objects (KBOs) and their
progeny
to study the chemical, dynamical, and collisional history of the
region
of the giant planets. The sensitivity of the WFC3 observations
will
allow us to go up to two magnitudes deeper than our ground based
studies,
allowing us the capability of optimally selecting a target list
for
a large survey rather than simply taking the few objects that can be
measured,
as we have had to do to date. We have carefully constructed a
sample
of 120 objects which provides both overall breadth, for a general
understanding
of these objects, plus a large enough number of objects in
the
individual dynamical subclass to allow detailed comparison between
and
within these groups. These objects will likely define the core
Kuiper
Belt compositional sample for years to come. While we have many
specific
results anticipated to come from this survey, as with any
project
where the field is rich, our current knowledge level is low, and
a
new instrument suddenly appears which can exploit vastly larger
segments
of the population, the potential for discovery -- both
anticipated
and not -- is extraordinary.
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/ACS/IR
11584
Resolving
the Smallest Galaxies with ACS
An
order of magnitude more dwarf galaxies are expected to inhabit the
Local
Group, based on currently accepted galaxy formation models, than
have
been observed. This discrepancy has been noted in environments
ranging
from the field to rich clusters, with evidence emerging that
lower
density regions contain fewer dwarfs per giant than higher density
regions,
in further contrast to model predictions. However, there is no
complete
census of the faintest dwarf galaxies in any environment. The
discovery
of the smallest and faintest dwarfs is hampered by the
limitations
in detecting such compact or low surface brightness
galaxies,
and this is compounded by the great difficulty in determining
accurate
distances to, or ascertaining group membership for, such faint
objects.
The M81 group provides a powerful means for establishing
membership
for faint galaxies in a low density region. With a distance
modulus
of 27.8, the tip of the red giant branch (TRGB) appears at I ~
24,
just within the reach of ground based surveys. We have completed a
65
square degree survey in the region around M81 with the CFHT/MegaCam.
Half
of our survey was completed before Cycle 16 and we were awarded
time
with WFPC2 to observe 15 new candidate dwarf galaxy group members
in
F606W and F814W bands in order to construct color-magnitude diagrams
from
which to measure accurate TRGB distances and determine star
formation
and metallicity histories. The data obtained show that 8 - 9
of
these objects are galaxies at the same distance as M81. In completing
our
survey, we have discovered an additional 8 candidate galaxies we
propose
to image with ACS in order to measure TRGB distances and
establish
membership. We also wish to re-observe our smallest candidate
group
member and a tidal dwarf candidate with deeper observations made
possible
with ACS. Once membership has been established for this second
set
of candidates, we will have a complete census of the dwarf galaxy
population
in the M8 group to M_r ~ -10, allowing us to obtain a firm
measurement
of the luminosity function faint-end slope, and, combined
with
previous HST data, to provide a complete inventory of the age and
abundance
properties for the collapsed core of the M81 group.
WFC3/ACS/IR
11563
Galaxies
at z~7-10 in the Reionization Epoch: Luminosity Functions to
<0.2L*
from Deep IR Imaging of the HUDF and HUDF05 Fields
The
first generations of galaxies were assembled around redshifts
z~7-10+,
just 500-800 Myr after recombination, in the heart of the
reionization
of the universe. We know very little about galaxies in this
period.
Despite great effort with HST and other telescopes, less than
~15
galaxies have been reliably detected so far at z>7, contrasting with
the
~1000 galaxies detected to date at z~6, just 200-400 Myr later, near
the
end of the reionization epoch. WFC3 IR can dramatically change this
situation,
enabling derivation of the galaxy luminosity function and its
shape
at z~7-8 to well below L*, measurement of the UV luminosity
density
at z~7-8 and z~8-9, and estimates of the contribution of
galaxies
to reionization at these epochs, as well as characterization of
their
properties (sizes, structure, colors). A quantitative leap in our
understanding
of early galaxies, and the timescales of their buildup,
requires
a total sample of ~100 galaxies at z~7-8 to ~29 AB mag. We can
achieve
this with 192 WFC3 IR orbits on three disjoint fields
(minimizing
cosmic variance): the HUDF and the two nearby deep fields of
the
HUDF05. Our program uses three WFC3 IR filters, and leverages over
600
orbits of existing ACS data, to identify, with low contamination, a
large
sample of over 100 objects at z~7-8, a very useful sample of ~23
at
z~8-9, and limits at z~10. By careful placement of the WFC3 IR and
parallel
ACS pointings, we also enhance the optical ACS imaging on the
HUDF
and a HUDF05 field. We stress (1) the need to go deep, which is
paramount
to define L*, the shape, and the slope alpha of the luminosity
function
(LF) at these high redshifts; and (2) the far superior
performance
of our strategy, compared with the use of strong lensing
clusters,
in detecting significant samples of faint z~7-8 galaxies to
derive
their luminosity function and UV ionizing flux. Our recent z~7.4
NICMOS
results show that wide-area IR surveys, even of GOODS-like depth,
simply
do not reach faint enough at z~7-9 to meet the LF and UV flux
objectives.
In the spirit of the HDF and the HUDF, we will waive any
proprietary
period, and will also deliver the reduced data to STScI. The
proposed
data will provide a Legacy resource of great value for a wide
range
of archival science investigations of galaxies at redshifts z~2-9.
The
data are likely to remain the deepest IR/optical images until JWST
is
launched, and will provide sources for spectroscopic followup by
JWST,
ALMA and EVLA.
COS/FUV
11491
COS
FUV External Flat Fields
Obtain
external spectra of flat field targets at different positions
along
the cross- dispersion direction of the FUV detector (and at a
variety
of FP-POS positions) in order to obtain an FUV flat field. The
choices
of gratings and positions of the target in the aperture have
been
made in order to maximize the coverage on the detector in the
cross-dispersion
direction and cover the entire region where science
spectra
will fall.
COS/FUV
11490
COS
FUV External Spectroscopic Performance - Part 2
The
goal of this activity is to verify the spatial resolution of COS in
the
FUV and to characterize the interdependence of the spatial and
spectral
resolution of the instrument in that wavelength band. By
stepping
the source along the cross-dispersion direction out to the edge
of
the PSA, we will be able to quantify the variation of the spatial
profile
of the source with off-axis position, both by measuring the
shape
and width of the profile and by measuring the amount of flux
transmitted
through the aperture as the source is stepped past the edge
of
the aperture. Aside from measuring the spatial resolution of COS
spectra,
this study will be particularly useful for understanding the
contamination
of sources near the targeted object in crowded stellar
fields.
This
test is ideally performed with a spatially unresolved point source
with
an emission line spectrum. Our observations with the PSA will
target
the symbiotic star LIN 358 in the Large Magellanic Cloud. This
star
produces little or no continuum in the FUV, but exhibits line
emission
from He II (particularly strong), C IV, N IV and N V. The
individual
lines are unresolved in FOS spectra of this object, but the
lines
within the C IV and N V doublets are well resolved from one
another.
This indicates that the emission lines in the COS observations
are
likely to be narrow (<~ 60 km/s).
These
observations will implement the following procedure: First, a
target
acquisition is performed to place the target at the center of the
aperture.
For each FUV grating we obtain moderately high S/N (~ 30 per
resel
counting statistics) observations at one central wavelength
setting
with the PSA. Next we repeat the sequence of observations at
each
of five additional positions, with offsets of 0.25, 0.5, 1.0, 1.5,
and
1.75 arcseconds in the cross-dispersion (Y) direction from the
center
of the aperture. The procedure is then repeated for five more
POSTARGs
offset in the negative cross-dispersion direction (-Y). This
results
in a total of 11 exposures with the G130M and G140L gratings.
For
observations with the G160M grating we include an additional set of
5
POSTARGs each along the positive (+X) and negative (-X) dispersion
directions.
The goal of these observations is to test variations in the
shape
and width of the profile along the dispersion direction, and to
compare
the results with those from the cross-dispersion direction.
All
of these observations will be performed in Time-Tag mode with
Flash=Yes
for all three FUV gratings, but with FP-POS set to the default
value
of 3.
The
observations with the BOA will be performed on the Galactic
symbiotic
star AG Draconis (M_V = 9.8). This object is a bright
recurrent
nova (period ~ 15 yrs) and a source of strong ultraviolet line
emission.
Here we obtain a single Time-Tag exposure for each of the four
FUV
gratings with the object centered in the BOA to evaluate the spatial
resolution
in this mode. We aim for S/N = 20 for the brightest emission
line
in each observation.
The
number of exposures in this program is somewhat larger than the
number
described in the Activity Summary, but is necessary to perform
the
intended tests of the COS spectral resolution.
This
activity is SMOV program COS 32.
Implementation
Method: Stored Commanding
Data
Requirements: Approximately 420 MB
Dependencies:
Execute after verification based upon results of Activity
COS
30 (Internal FUV Wavelength Calibration) (SMOV Proposal 11488)
Applicable
SMOV Requirements: L.10.4.2.3.12.2; L.10.4.2.3.12.3;
L.10.4.2.3.13
COS/FUV
11482
FUV
Detector Dark
Measure
the FUV 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 data in order to
verify
the nominal operation of the detector, and for use in the CalCOS
calibration
pipeline. Variations of count rate as a function of orbital
position
will be analyzed to find dependence of dark rate on proximity
to
the SAA.
This
is SMOV Activity COS-24.
COS/NUV
11477
COS
NUV External Spectroscopic Performance - Part 2
The
goal of this activity is to verify the spatial resolution of COS in
the
NUV and to characterize the interdependence of the spatial and
spectral
resolution of the instrument in that wavelength band. By
stepping
the source along the cross-dispersion direction out to the edge
of
the PSA, we will be able to quantify the variation of the spatial
profile
of the source with off-axis position, both by measuring the
shape
and width of the profile and by measuring the amount of flux
transmitted
through the aperture as the source is stepped past the edge
of
the aperture. Aside from measuring the spatial resolution of COS
spectra,
this study will be particularly useful for characterizing the
contamination
of sources near the targeted object in crowded stellar
fields.
This
test is ideally performed with a spatially unresolved point source
with
an emission line spectrum. Our observations with the PSA will
target
the Galactic symbiotic stars AG Draconis and He 2-38. The former
object
produces a low, nearly flat NUV continuum and exhibits line
emission
from He II (particularly strong), N III], Si III] and Bowen
fluorescence
line emission from OIII]. The lines are well resolved in
existing
STIS echelle spectra of this object, where they exhibit line
widths
ranging from 40 km/s to 60 km/s. We expect similar line widths in
our
COS observations. He 2-38, on the other hand, is considerably
fainter
than AG Dra in the NUV, due to presence of a dust shell around
the
source (it is a Mira-type system). The reddening toward He 2-38 is
also
considerable (E(B -V)=1.2).
Our
observations with the BOA will target another Galactic symbiotic
star,
RR Telescopii. This object exhibits similar line widths to AG Dra,
but
includes a rich array of Fe II emission lines as well.
These
observations will implement the following procedure: First, a
target
acquisition is performed to place the target at the center of the
aperture.
For each NUV grating we obtain moderately high S/N (~ 30 per
resel
counting statistics) observations at one central wavelength
setting
with the PSA. Next we repeat the sequence of observations at
each
of 5 additional positions, with offsets of 0.25, 0.5, 1.0, 1.5 and
1.75
arcseconds in the cross-dispersion direction (+Y). The procedure is
repeated
for 5 more POSTARGs offset in the negative cross-dispersion
direction
(-Y). This results in a total of 11 exposures with the G225M
and
G285M gratings. For observations with the G185M grating we include
an
additional set of 5 POSTARGs each along the positive (+X) and
negative
(-X) dispersion directions. The goal of these observations is
to
test variations in the shape and width of the profile along the
dispersion
direction. All of these observations will be performed in
Time-Tag
mode with Flash=Yes for all four NUV gratings, but with FP-POS
simply
set to the default value of 3. Our G230L observations will target
He
2-38, and will be performed with the same set of offsets (11) as the
G185M
and G225M gratings.
We
plan to perform additional NUV observations through the BOA of the
symbiotic
star RR Tel, where we will obtain a single TIME-TAG exposure
for
each of the four NUV gratings with the object centered in the BOA to
evaluate
the spatial resolution in this mode. We aim for S/N >= 20 in
these
observations.
This
activity is SMOV Program COS 17.
Implementation
Method: Stored Commanding
Data
Requirements: Approximately 420 MB
Dependencies:
Execute after verification based upon results of Activity
COS
15 (Internal NUV Wavelength Verification) (SMOV Program 11475).
Applicable
SMOV Requirements: L.10.4.2.3.7.2; L.10.4.2.3.7.3;
L.10.4.2.3.13
STIS20
11402
STIS-20
NUV MAMA Dark Monitor
The
STIS NUV-MAMA dark current is dominated by a phosphorescent glow
from
the detector window. Meta-stable states in this window are
populated
by cosmic ray impacts, which, days later, can be thermally
excited
to an unstable state from which they decay, emitting a UV
photon.
The equilibrium population of these meta-stable states is larger
at
lower temperatures; so warming up the detector from its cold safing
will
lead to a large, but temporary, increase in the dark current.
To
monitor the decay of this glow, and to determine the equilibrium dark
current
for Cycle 17, four 1380s NUV-MAMA ACCUM mode darks should be
taken
each week during the SMOV period. Once the observed dark current
has
reached an approximate equilibrium with the mean detector
temperature,
the frequency of this monitor can be reduced to one pair of
darks
per week.
WFC3/ACS/IR
11235
HST
NICMOS Survey of the Nuclear Regions of Luminous Infrared Galaxies
in
the Local Universe
At
luminosities above 10^11.4 L_sun, the space density of far-infrared
selected
galaxies exceeds that of optically selected galaxies. These
`luminous
infrared galaxies' (LIRGs) are primarily interacting or
merging
disk galaxies undergoing enhanced star formation and Active
Galactic
Nuclei (AGN) activity, possibly triggered as the objects
transform
into massive S0 and elliptical merger remnants. We propose
NICMOS
NIC2 imaging of the nuclear regions of a complete sample of 88
L_IR
> 10^11.4 L_sun luminous infrared galaxies in the IRAS Revised
Bright
Galaxy Sample (RBGS: i.e., 60 micron flux density > 5.24 Jy).
This
sample is ideal not only in its completeness and sample size, but
also
in the proximity and brightness of the galaxies. The superb
sensitivity
and resolution of NICMOS NIC2 on HST enables a unique
opportunity
to study the detailed structure of the nuclear regions,
where
dust obscuration may mask star clusters, AGN, and additional
nuclei
from optical view, with a resolution significantly higher than
possible
with Spitzer IRAC. This survey thus provides a crucial
component
to our study of the dynamics and evolution of IR galaxies
presently
underway with Wide-Field, HST ACS/WFC3, and Spitzer IRAC
observations
of these 88 galaxies. Imaging will be done with the F160W
filter
(H-band) to examine as a function of both luminosity and merger
stage:
(i) the luminosity and distribution of embedded star clusters,
(ii)
the presence of optically obscured AGN and nuclei, (iii) the
correlation
between the distribution of 1.6 micron emission and the
mid-IR
emission as detected by Spitzer IRAC, (iv) the evidence of bars
or
bridges that may funnel fuel into the nuclear region, and (v) the
ages
of star clusters for which photometry is available via ACS/WFC3
observations.
The NICMOS data, combined with the HST ACS, Spitzer, and
GALEX
observations of this sample, will result in the most comprehensive
study
of merging and interacting galaxies to date.
FLIGHT
OPERATIONS SUMMARY:
Significant
Spacecraft Anomalies: (The following are preliminary reports
of
potential non-nominal performance that will be investigated.)
HSTARS:
(None)
COMPLETED
OPS REQUEST: (None)
COMPLETED
OPS NOTES: (None)
SCHEDULED
SUCCESSFUL
FGS
GSAcq
34
34
FGS
REAcq
29
29
OBAD
with Maneuver 29
29
SIGNIFICANT
EVENTS: (None)