Daily Report #4925

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 z7,
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 procedu 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 procedu 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)