HUBBLE
SPACE TELESCOPE - Continuing to Collect World Class Science
DAILY
REPORT #5163
PERIOD
COVERED: 5am August 18 - 5am August 19, 2010 (DOY 230/09:00z-231/09:00z)
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
8
8
FGS
REAcq
7
7
OBAD
with Maneuver 4
4
SIGNIFICANT
EVENTS: (None)
OBSERVATIONS
SCHEDULED:
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.
ACS/WFC3
11604
The
Nuclear Structure of OH Megamaser Galaxies
We
propose a snapshot survey of a complete sample of 80 OH megamaser
galaxies.
Each galaxy will be imaged with the ACS/WFC through F814W and
a
linear ramp filter (FR656N or FR716N or FR782N or FR853N) allowing us
to
study both the spheroid and the gas morphology in Halpha + [N II]. We
will
use the 9% ramps FR647M (5370-7570 angstroms) centered at 7000
angstroms
and FR914M (7570-10, 719 angstroms) 8000 angstroms for
continuum
subtraction for the high and low z objects respectively. OH
megamaser
galaxies (OHMG) form an important class of ultraluminous
IR-galaxies
(ULIRGs) whose maser lines emit QSO-like luminosities.
ULIRGs
in general are associated with recent mergers but it is often
unclear
whether their power output is dominated by starbursts or a
hidden
QSO because of the high absorbing columns which hide their nuclei
even
at X-ray wavelengths. In contrast, OHMG exhibit strong evidence for
the
presence of an energetically important and recently triggered active
nucleus.
In particular it is clear that much of the gas must have
already
collapsed to form a nuclear disk which may be the progenitor of
a
circum-nuclear torus, a key element of the unified scheme of AGN. A
great
advantage of studying OHMG systems over the general ULIRG
population,
is that the circum-nuclear disks are effectively "fixed" at
an
inner, edge on, orientation, eliminating varying inclination as a
nuisance
parameter. We will use the HST observations in conjunction with
existing
maser and spectroscopic data to construct a detailed picture of
the
circum-nuclear regions of a hitherto relatively neglected class of
galaxy
that may hold the key to understanding the relationship between
galaxy
mergers, nuclear star-formation, and the growth of massive black
holes
and the triggering of nuclear activity.
COS/NUV/FUV
11718
The
Stellar Halos of Dwarf Galaxies
The
metal-poor stellar halo is the oldest extended structure in the
Galaxy.
Such halos are thought to form through hierarchical merging, and
contain
stars pulled from accreted subhalos. The diffuse stellar halo
therefore
stores information about the prop reties of the accreted
galaxies
(i.e., their orbits, stellar masses, and metallicities). It is
therefore
unsurprising that stellar halos have become a popular probe of
the
early epoch of galaxy formation.
Almost
all current work on stellar halos has focused on massive
galaxies,
however. We propose to extend the work on stellar halos to
much
lower mass scales, by studying the halos of faint dwarf galaxies.
By
taking halo studies into the dwarf galaxy regime, we can probe
exceptionally
small mass scales for the accreted halos. At these mass
scales
the effects of reionization and supernova feedback have the
largest
impact on the galaxy population. Stellar halos of dwarf galaxies
are
therefore a sensitive probe of the key processes needed to resolve
the
lack of substructure observed at low masses.
We
are requesting two far-field ACS pointings for the three closest
isolated
nearby dwarf irregular galaxies whose inner halos have already
been
mapped with the ACS Nearby Galaxy Survey Treasury. These outer
fields
will allow us to trace the halo out to roughly half the virial
radius,
further than any previous study. We will use the resulting
distribution
of halo stars (1) to unambiguously measure the structure of
the
stellar halo, with minimal contamination from the main galaxy; (2)
to
constrain the flattening of the stellar halo; (3) to measure the
metallicity
of halo stars as a function of radius; (4) to correlate any
changes
in halo profile with changes in metallicity. The resulting data
will
constrain models of halo accretion and the epoch of reionization.
STIS/CCD
11596
Coronagraphic
Imaging of Debris Disks Containing Gas
We
recently found a new sample of edge-on debris disks using the Spitzer
Space
Telescope. These disks are particularly valuable because they have
observable
circumstellar gas as well as dust. They double the small
number
of debris disks that can be used to study gas-dust interactions
in
optically-thin disks, as well as the evolution of circumstellar gas
during
the terrestrial planet-forming phase. We propose HST-STIS
coronagraphic
imaging of the two closest disks from our sample, in order
to
image light scattered from the dust disks in a broad optical
bandpass.
These observations will provide a wealth of information about
the
disks, including their sizes, radial surface brightness profiles,
and
basic morphologies (ring-like or smooth disk). They may also reveal
dust
structures (e.g. clumps) that are often seen in optical images of
debris
disks and may be generated by the influence of unseen planets.
This
proposed program is a crucial step towards full characterization of
the
circumstellar material in two important debris disks.
STIS/CCD
11845
CCD
Dark Monitor Part 2
Monitor
the darks for the STIS CCD.
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/MA1/MA2
11857
STIS
Cycle 17 MAMA Dark Monitor
This
proposal monitors the behavior of the dark current in each of the
MAMA
detectors.
The
basic monitor takes two 1380s ACCUM darks each week with each
detector.
However, starting Oct 5, pairs are only included for weeks
that
the LRP has external MAMA observations planned. The weekly pairs of
exposures
for each detector are linked so that they are taken at
opposite
ends of the same SAA free interval. This pairing of exposures
will
make it easier to separate long and short term temporal variability
from
temperature dependent changes.
For
both detectors, additional blocks of exposures are taken once every
six
months. These are groups of five 1314s FUV-MAMA Time-Tag darks or
five
3x315s NUV ACCUM darks distributed over a single SAA-free interval.
This
will give more information on the brightness of the FUV MAMA dark
current
as a function of the amount of time that the HV has been on, and
for
the NUV MAMA will give a better measure of the short term
temperature
dependence.
WFC3/ACS/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 follow up by
JWST,
ALMA and EVLA.
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<z<1.8 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
0.5<z<2.2;
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/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
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
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
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.