Daily Report #5155

HUBBLE SPACE TELESCOPE - Continuing to Collect World Class Science

DAILY REPORT #5155

PERIOD COVERED: 5am August 6 - 5am August 9, 2010 (DOY 218/09:00z-221/09:00z)

FLIGHT OPERATIONS SUMMARY:

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

HSTARS:

12351 - GSAcq (1,2,1) scheduled at 218/10:49:29z and REAcqs(1,2,1)
scheduled at 218/11:51:11z, at 218/13:27:02z, and at 218/15:09:02z all
results in fine lock backup (1,0,1) using FGS-1, scan step limit
exceeded on FGS-2.

Observations possibly affected: WFC3 113-118 Proposal ID#11694; COS
132 Proposal ID#11579; ACS 124-125 Proposal ID#11996; STIS 22-23
Proposal ID#11845; STIS 24, 25, 26 Proposal ID#11847

COMPLETED OPS REQUEST: (None)

COMPLETED OPS NOTES: (None)

SCHEDULED SUCCESSFUL
FGS GSAcq 15 15
FGS REAcq 24 24
OBAD with Maneuver 11 11

SIGNIFICANT EVENTS: (None)



OBSERVATIONS SCHEDULED:

ACS/WFC/WFC3/IR/UV 12056

A Panchromatic Hubble Andromeda Treasury - I

We propose to image the north east quadrant of M31 to deep limits in
the UV, optical, and near-IR. HST imaging should resolve the galaxy
into more than 100 million stars, all with common distances and
foreground extinctions. UV through NIR stellar photometry (F275W,
F336W with WFC3/UVIS, F475W and F814W with ACS/WFC, and F110W and
F160W with WFC3/NIR) will provide effective temperatures for a wide
range of spectral types, while simultaneously mapping M31's
extinction. Our central science drivers are to: understand high-mass
variations in the stellar IMF as a function of SFR intensity and
metallicity; capture the spatially-resolved star formation history of
M31; study a vast sample of stellar clusters with a range of ages and
metallicities. These are central to understanding stellar evolution
and clustered star formation; constraining ISM energetics; and
understanding the counterparts and environments of transient objects
(novae, SNe, variable stars, x-ray sources, etc.). As its legacy, this
survey adds M31 to the Milky Way and Magellanic Clouds as a
fundamental calibrator of stellar evolution and star-formation
processes for understanding the stellar populations of distant
galaxies. Effective exposure times are 977s in F275W, 1368s in F336W,
4040s in F475W, 4042s in F814W, 699s in F110W, and 1796s in F160W,
including short exposures to avoid saturation of bright sources. These
depths will produce photon-limited images in the UV. Images will be
crowding-limited in the optical and NIR, but will reach below the red
clump at all radii. The images will reach the Nyquist sampling limit
in F160W, F475W, and F814W.

S/C 12046

COS FUV DCE Memory Dump

Whenever the FUV detector high voltage is on, count rate and current
draw information is collected, monitored, and saved to DCE memory.
Every 10 msec the detector samples the currents from the HV power
supplies (HVIA, HVIB) and the AUX power supply (AUXI). The last 1000
samples are saved in memory, along with a histogram of the number of
occurrences of each current value.

In the case of a HV transient (known as a "crackle" on FUSE), where
one of these currents exceeds a preset threshold for a persistence
time, the HV will shut down, and the DCE memory will be dumped and
examined as part of the recovery procedure. However, if the current
exceeds the threshold for less than the persistence time (a
"mini-crackle" in FUSE parlance), there is no way to know without
dumping DCE memory. By dumping and examining the histograms regularly,
we will be able to monitor any changes in the rate of "mini-crackles"
and thus learn something about the state of the detector.

ACS/WFC 11996

CCD Daily Monitor (Part 3)

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

WFC3/IR/S/CCD 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/IR 11920

WFC3 IR Image Quality

The IR imaging performance over the detector will be assessed
periodically (every 4 months) in two passbands to check for image
stability. The field around star 58 in the open cluster NGC188 is the
chosen target because it is sufficiently dense to provide good
sampling over the FOV while providing enough isolated stars to permit
accurate PSF (point spread function) measurement. It is available
year-round and used previously for ACS image quality assessment. The
field is astrometric, and astrometric guide stars will be used, so
that the plate scale and image orientation may also be determined if
necessary (as in SMOV proposals 11437 and 11443). Full frame images
will be obtained at each of 4 POSTARG offset positions designed to
improve sampling over the detector in F098M, F105W, and F160W. The
PSFs will be sampled at 4 positions with subpixel shifts in filters
F164N and F127M.

This proposal is a periodic repeat (once every 4 months) of the visits
in SMOV proposal 11437 (activity ID WFC3-24). The data will be
analyzed using the code and techniques described in ISR WFC3 2008-41
(Hartig). Profiles of encircled energy will be monitored and presented
in an ISR. If an update to the SIAF is needed, (V2, V3) locations of
stars will be obtained from the Flight Ops. Sensors and Calibrations
group at GSFC, the (V2, V3) of the reference pixel and the orientation
of the detector will be determined by the WFC3 group, and the
Telescopes group will update and deliver the SIAF to the PRDB branch.

The specific PSF metrics to be examined are encircled energy for
aperture diameter 0.25, 0.37, and 0.60 arcsec, FWHM, and sharpness.
(See ISR WFC3 2008-41 tables 2 and 3 and preceding text.) ~20 stars
distributed over the detector will be measured in each exposure for
each filter. The mean, rms, and rms of the mean will be determined for
each metric. The values determined from each of the 4 exposures per
filter within a visit will be compared to each other to see to what
extent they are affected by "breathing". Values will be compared from
visit to visit, starting with the values obtained during SMOV after
the fine alignment has been performed, to see if the measures of the
compactness of the PSF indicate degradation over time. The analysis
will be repeated for stars on the inner part of the detector and stars
on the outer part of the detector to check for differential
degradation of the PSF.

As an example of the analysis, one can examine the sharpness of the
F160W PSF exposures made during thermal vacuum testing (ISR WFC3
2008-41). To compare two samples, one can define the PSFs on each half
of the detector (lower and upper) as a sample (with 7 and 8 PSFs,
respectively). The mean, rms, and rms of the mean sharpness are
0.0826, 0.0067, and 0.0027 for one half, and 0.0773, 0.0049, and
0.0019 for the other. The difference of the means is 0.0053 and the
statistical error in that difference is 0.0033, so the difference is
not significant.

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 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/UV 11904

UVIS Droplets

To characterize the effects of the contamination (i.e., droplets) on
the UVIS window, we will observe a star cluster in three wide band
filters (F225W, F555W, and F814W) as well as a narrow band filter
(F502N) and step the stars in the cluster across randomly located
droplets. The step size is 20 pixels, and we execute a five point line
dither for each filter. This should provide for observations both on
and off the droplets, for the same star. Internal flat fields are also
obtained, but, due to the high f/# of the internal calibration system,
the flats will be of limited utility, but will serve to map and
crudely track any changes in the droplets. The cluster needs to
contain both hot and cool stars, and therefore we select NGC 6752, a
nearby globular with a hot horizontal branch. Note, although the total
population of HB stars may be larger in systems such as NGC 2419, NGC
6715, and NGC 2808, those clusters are much further away and will not
provide a high density of stars over the global image (the droplets
are located over the entire frame). There will be three visits
(initial, 7 days later, and 30 days later), with each visit requiring
4 orbits. The total program thus requires 12 orbits total.

COS/NUV 11900

NUV Internal/External Wavelength Scale Monitor

This program monitors the offsets between the wavelength scale set by
the internal wavecal versus that defined by absorption lines in
external targets. This is accomplished by observing two external
radial velocity standard targets: HD187691 with G225M and G285M and
HD6655 with G285M and G230L. The two standard targets have little flux
in the wavelength range covered by G185M and so Feige 48 (sdO) is
observed with this grating. Both Feige 48 and HD6655 are also observed
in SMOV. The cenwaves observed in this program are a subset of the
ones used during Cycle 17. Observing all cenwaves would require a
considerably larger number of orbits. Constraints on scheduling of
each target are placed so that each target is observed once every ~2-3
months. Observing the three targets every month would also require a
considerably larger number of orbits.

STIS/CCD 11847

CCD Bias Monitor-Part 2

Monitor the bias in the 1x1, 1x2, 2x1, and 2x2 bin settings at gain=1,
and 1x1 at gain = 4, to build up high-S/N superbiases and track the
evolution of hot columns.

STIS/CCD 11845

CCD Dark Monitor Part 2

Monitor the darks for the STIS CCD.

COS/NUV/FUV 11741

Probing Warm-Hot Intergalactic Gas at 0.5 z 1.3 with a Blind
Survey for O VI, Ne VIII, Mg X, and Si XII Absorption Systems

Currently we can only account for half of the baryons (or less)
expected to be found in the nearby universe based on D/H and CMB
observations. This "missing baryons problem" is one of the
highest-priority challenges in observational extragalatic astronomy.
Cosmological simulations suggest that the baryons are hidden in
low-density, shock-heated intergalactic gas in the log T = 5 - 7
range, but intensive UV and X-ray surveys using O VI, O VII, and O
VIII absorption lines have not yet confirmed this prediction. We
propose to use COS to carry out a sensitive survey for Ne VIII and Mg
X absorption in the spectra of nine QSOs at z(QSO) 0.89. For the
three highest-redshift QSOs, we will also search for Si XII. This
survey will provide more robust constraints on the quantity of baryons
in warm-hot intergalactic gas at 0.5 z 1.3, and the data will
provide rich constraints on the metal enrichment, physical conditions,
and nature of a wide variety of QSO absorbers in addition to the
warm-hot systems. By comparing the results to other surveys at lower
redshifts (with STIS, FUSE, and from the COS GTO programs), the
project will also enable the first study of how these absorbers evolve
with redshift at z 1. By combining the program with follow-up galaxy
redshift surveys, we will also push the study of galaxy-absorber
relationships to higher redshifts, with an emphasis on the
distribution of the WHIM with respect to the large-scale matter
distribution of the universe.

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 z6 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 a (1) Detect Lya
in ~100 galaxies with z5.6 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 0.5z1.8 to measure the evolution of the
extinction-corrected star formation density across the peak epoch of
star formation. This is over an order-of-magnitude improvement in the
current statistics, from the NICMOS Parallel grism survey. (5) Trace
``cosmic downsizing" from 0.5z2.2; and (6) Estimate the evolution in
reddening and metallicty in star- forming galaxies and measure the
evolution of the Seyfert population. For hundreds of spectra we will
be able to measure one or even two line pair ratios -- in particular,
the Balmer decrement and [OII]/[OIII] are sensitive to gas reddening
and metallicity. As a bonus, the G102 grism offers the possibility of
detecting Lya emission at z=7-8.8.

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 11694

Mapping the Interaction Between High-Redshift Galaxies and the
Intergalactic Environment

With the commissioning of the high-throughput large-area camera
WFC3/IR, it is possible for the first time to undertake an efficient
survey of the rest-frame optical morphologies of galaxies at the peak
epoch of star formation in the universe. We therefore propose deep
WFC3/IR imaging of over 320 spectroscopically confirmed galaxies
between redshift 1.6 z 3.4 in well-studied fields which lie along
the line of sight to bright background QSOs. The spectra of these
bright QSOs probe the IGM in the vicinity of each of the foreground
galaxies along the line of sight, providing detailed information on
the physical state of the gas at large galactocentric radii. In
combination with our densely sampled UV/IR spectroscopy, stellar
population models, and kinematic data in these fields, WFC3/IR imaging
data will permit us to construct a comprehensive picture of the
structure, dynamics, and star formation properties of a large
population of galaxies in the early universe and their effect upon
their cosmological environment.

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/IR 11631

Binary Brown Dwarfs and the L/T Transition

Brown dwarfs traverse spectral types M, L and T as their atmospheric
structure evolves and they cool into oblivion. This SNAPSHOT program
will obtain WFC3-IR images of 45 nearby late-L and early-T dwarfs to
investigate the nature of the L/T transition. Recent analyses have
suggested that a substantial proportion of late-L and early-T dwarfs
are binaries, comprised of an L dwarf primary and T dwarf secondary.
WFC3-IR observations will let us quantify this suggestion by expanding
coverage to a much larger sample, and permitting comparison of the L/T
binary fraction against 'normal' ultracool dwarfs. Only eight L/T
binaries are currently known, including several that are poorly
resolved: we anticipate at least doubling the number of resolved
systems. The photometric characteristics of additional resolved
systems will be crucial to constraining theoretical models of these
late-type ultracool dwarfs. Finally, our data will also be eminently
suited to searching for extremely low luminosity companions,
potentially even reaching the Y dwarf regime.

WFC3/ACS/UVIS 11613

GHOSTS: Stellar Outskirts of Massive Spiral Galaxies

We propose to continue our highly successful GHOSTS HST survey of the
resolved stellar populations of nearby, massive disk galaxies using
SNAPs. These observations provide star counts and color-magnitude
diagrams 2-3 magnitudes below the tip of the Red Giant Branch of the
outer disk and halo of each galaxy. We will measure the metallicity
distribution functions and stellar density profiles from star counts
down to very low average surface brightnesses, equivalent to ~32 V-mag
per square arcsec.

This proposal will substantially improve our unique sampling of galaxy
outskirts. Our targets cover a range in galaxy mass, luminosity,
inclination, and morphology. As a function of these galaxy properties,
this survey provides: - the most extensive, systematic measurement of
radial light profiles and axial ratios of the diffuse stellar halos
and outer disks of spiral galaxies; - a comprehensive analysis of halo
metallicity distributions as function of galaxy type and position
within the galaxy; - an unprecedented study of the stellar metallicity
and age distribution in the outer disk regions where the disk
truncations occur; - the first comparative study of globular clusters
and their field stellar populations.

We will use these fossil records of the galaxy assembly process to
test halo formation models within the hierarchical galaxy formation
scheme.

ACS/SBC/COS/NUV/FUV 11579

The Difference Between Neutral- and Ionized-Gas Metal Abundances in
Local Star-Forming Galaxies with COS

The metallicity of galaxies and its evolution with redshift is of
paramount importance for understanding galaxy formation. Abundances in
the interstellar medium (ISM) are typically determined using
emission-line spectroscopy of HII regions. However, since HII regions
are associated with recent SF they may not have abundances typical for
the galaxy as a whole. This is true in particular for star-forming
galaxies (SFGs), in which the bulk of the metals may be contained in
the neutral gas. It is therefore important to directly probe the metal
abundances in the neutral gas. This can be done using absorption lines
in the Far UV. We have developed techniques to do this in SFGs, where
the absorption is measured for sightlines toward bright SF regions
within the galaxy itself. We have successfully applied this technique
to a sample of galaxies observed with FUSE. The results have been very
promising, suggesting in I Zw 18 that abundances in the neutral gas
may be up to 0.5 dex lower than in the ionized gas. However, the
interpretation of the FUSE data is complicated by the very large FUSE
aperture (30 arcsec), the modest S/N, and the limited selection of
species available in the FUSE bandpass. The advent of COS on HST now
allows a significant advance in all of these areas. We will therefore
obtain absorption line spectroscopy with G130M in the same sample for
which we already have crude constraints from FUSE. We will obtain
ACS/SBC images to select the few optimal sightlines to target in each
galaxy. The results will be interpreted through line-profile fitting
to determine the metal abundances constrained by the available lines.
The results will provide important new insights into the metallicities
of galaxies, and into outstanding problems at high redshift such as
the observed offset between the metallicities of Lyman Break Galaxies
and Damped Lyman Alpha systems.

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
follow up by JWST, ALMA and EVLA.